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Roof top Solar for domestic needs @ Bangalore - can I do it today?

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Power

A chance conversation with an acquaintance who works at a Solar Energy firm gave me a picture of the possibilities that await us. Now, I do read Solar Power/Panel Blogs/Forums etc once in a while, and have some idea of developments in the area. But I, like many of you I am sure, don't know much about the exact options available for me to try solar power here in Bangalore as an option to reduce my dependency on the Government's unreliable Power Grid.

What do I want to know? Here is a list.

  • Daytime needs - Solar Power as primary source, and BESCOM only as a backup
  • Night - If practically possible, some solution would be good , but not really a need, BESCOM for night and Surya Maami for the day is perfectly fine.
  • Community grid/pooling - I am told it may not be possible to run high wattage appliances on solar power. If every house in my community decides to go Solar, and if we make a local area grid, can this "pooling" serve the variable power needs of the community?
  • Price - Life of one time Investments that are needed, and Savings expected
  • Surface area requirements - how much needed for typical household needs (4-5 Kw)
  • Last, what are the government incentives for a consumer like me, or my community to go Solar!?

When I think Solar, either those water heaters come to mind, or the various rural market focused products (lanterns, cookers etc). Why isn't there enough push for urban or regular consumer applications?

Some data points I get are like this

  • Need about 80 square feet area for 1 Kw worth power
  • Cost for this may be about Rs 3 lakhs
  • Whatever is required to integrate Solar supply with Government grid (BESCOM) so that Solar would be primary and BESCOM only for backup or variable needs exists, and is most likely included in the above price estimates
  • Panels last for 25-30 years.

Adding it all up, let us see what is practical or possible right now

  • For 5 Kw worth power, I would require 400 sqft of roof space.
  • Appx cost would be 15 lakhs, I assume including some batteries/inverter/charge controller etc.
  • Assume that this would serve me for 15 years, and I would be using BESCOM for 50% of my needs
  • 1000 Rs Electricity bill would be cut to half, Rs 500 saved per month.
  • 6000 an year, 9 lakhs over 15 years at today's costs. And I am not including annual maintenance costs, simply because I don't know!

Do the numbers above look right?

The two answers I don't have are:

  • If a community of 500 families join in, does the cost/benefit equation change in anyway?
  • I bet government will have incentives for communities too? What exactly do they have, and does it change the cost/benefit equation significantly?

So then, please add and correct if you know more.Won't we really like to explore this emerging environment friendly possibility!?

cheers,

SB aka Pranav

PS: Image above is sourced from Partha Das Sharma's blog

Comments

sanjayv's picture

Short reponse

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SB, I can expand on solar or make a page of gyaan when time permits.  This officially falls within my area of expertise, unlike all the other stuff I write on.  For the time being, let me comment on your numbers.

 

  • Need about 80 square feet area for 1 Kw worth power
  • Cost for this may be about Rs 3 lakhs
  • Whatever is required to integrate Solar supply with Government grid (BESCOM) so that Solar would be primary and BESCOM only for backup or variable needs exists, and is most likely included in the above price estimates
  • Panels last for 25-30 years

80 sq feet for 1 kW worth of power - very optimistic.  One a properly oriented panel, on a clear day, around noon, you could hope to get 1kW of power from about 100 square feet of panel (high efficiency, should be crystalline silicon, not amorphous).  On an average, you will get far less.

Cost for one installed kW may be about 3 lakhs - sounds like a reasonable estimate.  May be a bit higher than this number, but close.

There are many options for grid integrated solar.  One option is a net metered connection whcih may not be legal in India at this point, where your meter spins backward when you are pumping energy back into the grid and forward when you are drawing net power from the grid.

Good quality panels today easily last 25-30 years with only small degradation in performance.

 

nl.srinivas's picture

What about batteries?

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What about the batteries? Unless we have a proper mechanism to dispose off or recycle batteries we should never go for this solution. The ill effects of chemicals (cadminum, lead, potassium, and  many more) used in the batteries are all too well know if they get mixed with air, ground and water.

This is one thing we simply cannot ignore.


silkboard's picture

Sanjay - local area grid type thing?

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Good thing Sanjay, so this is your domain then.

Net metered connection is good for Grid integration. But before going into giving back to the grid, I want to know if residental communities can pool in to get more benefits - both in terms of technollogy, and givt incentives?

  • Technology side - everyone 'contributing' 300 sqft roof space, say 100 houses. So total 30000 sqft area, but not all at one place. All this joined into one local area grid. Doable? Any advantages over each house going on its own?
  • Policy side - I am told individual households don't get any incentive or subsidy if they go solar (panels, battery pack etc). But if societies or communities do it, they get govt benefits.

Any idea?

Srinivas

Yes, yes. Aware of battery thing. I was exploring practical angles, but this too matters, cost angle - replacement cycle. and disposal angle (not explored yet)

sanjayv's picture

Grid solar

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Well, I am not aware of anyone doing pooling in a local grid like you describe.  That does not mean that it has not been tried anywhere.  There are typically two key issues with this concept that I can think of.

  1. Solar PV power output is DC (as opposed to the AC-alternating current in the grid).  DC is lower voltage and hence higher current for the same power output.  So one needs thicker gauge wire in order to move the power over larger distances.  Once you have multiple homes and distances to cover, it may not work out to be cost effective. If the plan is to make it AC power, one might as well integrate it with the local electricity grid.
  2. Secondly, demand is always cyclical and solar is a resource that can vary from second to second (clouds), over a day, over weeks and over the year. One community could be getting sun while another chunk one km away could be under a cloud.  So if your idea is that  several houses can pool together and meet the average demand - that does not always work.  A single cloud obscuring the sun for five minutes can bring down your grid, or too many homes trying to do things and causing a demand spike can do the same.

Hopefully, this explanation makes sense.  Do expand on your idea further if my explanation does not make sense and we can take this discussion forward.

silkboard's picture

With BESCOM as backup?

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Sanjay, with BESCOM as backup for variable needs at larger level, and a local Solar Grid with community pooling to take care of variable use at local level, it looks to me that you could have a solution where Solar supplies as much as it can, and neighbours first, and BESCOM next fills in when needed?

Should probably call and ask BP Solar or some other company. For all you know, they may have already installed similarly designed systems.

Naveen's picture

Solar Power Grid & India's poor progress

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Here is the wiki article about India.

Here is a link to what is happening in China re. solar grid.

Hope the ambitious "Jawaharlal Nehru National Solar Mission" will not turn out to be just another JNNURM !

Rudra's picture

Calculation mistake and alternative cheaper solar equipment.

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 you said it might cost 15 lakh for 5 KW and might last for 15 yrs.

assuming on an average monthly saving due to solar energy = Rs.1000/- then yearly it will be 12,000 and for 15 years it comes to  1,80, 000(1 lakh 80 thousand). which is not feasible.

If government can take the 50% burden of installation (I think i am too greedy on this) or weaving of the import duty tax exclusively on solar energy panels while importing from other country would be cheaper.

For 10 KW  it costs 3400 Euros in Germany that is 2,04,000(2 lakh 4 thousand).

Source: http://www.redorbit.com/news/science/1748434/us_germany_engaged_in_pricing_war_for_solar_panels/index.html

murali772's picture

Limitations of the solar option

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So, while solar power is desirable, we should proceed cautiously.  Global spending on solar R&D runs into billions, and any breakthroughs will come from abroad. We should not waste money duplicating global R&D. Rather, we should limit ourselves to pilot projects, testing the best global technologies in Indian conditions.

For the full text of the column by Swaminathan Aiyer in the Sunday TOI, click here

Muralidhar Rao
silkboard's picture

Any more data anyone - can this be done?

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Wanted to see if this can really be done for residential communities with enough space on rooftops for panels.

Also, if we can detail this, we can get deper into BESCOM/KREC etc to see if they are doing their best to promote such schemes.

Any domain experts willing to spread some gyan?

silkboard's picture

finally, got it - its called solar power conditioning unit

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First of all, forget the grid inter-connection part. That is a separate discussion, seee sanjayv's post on this subject.

Requirement

Recently, we started looking for a Solar system for a house. The house is in a rural area, what we were looking for is this

  • The system would have two sources for taking in power, Solar, and Grid (*ESCOM)
  • System should prefer using Solar over grid.
  • Want full solution from one vendor, unless buying separate components (panels, batteries, charging unit, inverter) is going to be significantly cheaper.

Basically, instead of buying a standard UPS (batteries + inverter), we were looking to buy a system with a special inverter that can take in charging current from Solar panels also. That's it.

Solution

So after some asking and searching around, we figured that what we were looking for is called "Solar Power Conditioning Unit". It can charge from either Solar panels, or Grid, and comes programmed to "prefer" Solar over Grid. To use a manufactures language:

The unit includes an integrated system to charge the battery bank through either Solar Power or Grid . The Solar Power Conditioning Unit continuously monitors the charging of the battery bank on parameters such as load, battery voltage and solar power output. When all batteries in the battery bank are fully charged to a predetermined level, the Solar Power Conditioning Unit automatically disconnects itself from the Solar or Grid.

Costs?

The quotes we got are like this. For a 4 Kw Solar system (Conditioning Unit) that we are told includes everything (we would double confirm only after its fully installed), total cost after subsidies would be Rs 1.4 Lakhs.

Compare this to buying just a UPS system of similar capabilities, is around Rs 42K

So we are paying over 3x to buy some freedom from Grid, and feel green about ourselves.

Naveen's picture

Storage is primary

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Compare this to buying just a UPS system of similar capabilities, is around Rs 42K

Exactly - unless this becomes cost efficient + storage solutions (for more than the currently available battery for 2-odd hrs) are found, this will remain a fancy & out of reach for the middle-class.

s_yajaman's picture

My two cents

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SB,

 

 Why do you need 4 KW of power to start with?  For your heating use a solar water heater (not PV) which will cost some 30 or 40000.  That can knock off 2 KW straight out of your load.  

What you are looking for is a peak load of 1.5 KW (some CFLs, fans, washing m/c, refrigerator).  With some intelligent use of sunlight http://www.bbc.co.uk/news/world-asia-pacific-14967535 you can reduce the lighting needs during the day.

Can't compare UPS and solar.  You need to charge the UPS using grid electricity.  

In a few years given our  track record of adding power and fuel shortage (both coal and gas) it will be the difference between having electricity and living in darkness.

http://www.moneycontrol.com/news/business/india-may-miss-11th-plan-power-capacity-addition-target_585287.html

http://www.thehindu.com/business/Economy/article2924660.ece

I would say go for it.

Srivathsa

Drive safe.  It is not just the car maker which can recall its product.

sanjayv's picture

Solar design

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SB,  Careful design is necessary to size a solar system properly.  For starters... what Srivathsa asked is a perfect question.  Why 4 kW?  Do you want to go through a design case study using this planned installation?  Start with a goal of going 100% solar and then work our what is feasible, practical and affordable.  We can do it together and then you can post it here on Praja.

Bheema.Upadhyaya's picture

I am seriously planning for alternate energy

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I am getting in touch with Adarsh of http://www.ecosaveindia.com/  

" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
idontspam's picture

I am stuck on figuring out

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I am stuck on figuring out how to size my load? :)

silkboard's picture

great! Sanjay, help me size and buy please

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Bheema, IDS, and myself - so three alternate energy guys are interested right here! So Sanjay, help us with sizing please.

This village house that we want to put solar on, here are the specs

  • 1/2 hp motor to pump water up to a rooftop water tank
  • 5 CFLs, 3 Fans
  • 1 Fridge
  • 1 TV (power needs documented as 140W)

This is it. Questions:

  • What capacity do I need? I see that Solar Power Conditioning Units are rated by some distributors in KVA (you need 250 KVA), and by some in Kw. This guy I went to said 4Kw is more than enough for your needs. He wasn't sure if I will be able to operate the 1/2 hp water pump though.
  • Will it be cheaper if I buy panel, betteries, charge units separately?
  • Can I be completely grid-free? This is not a deal breaker, just curious, that's all.

I am trying not to mention distributor/manufacturer's names etc. Will do so when final purchase is done. As I said, I have a quote for 1.4L, 4Kw, all included. after subsidy.

silkboard's picture

Naveev/srivathsa/bheema ...

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sorry, missed replying to your comments

Naveen - I think there are enough early adopters interested. Plus, the whole country anyway is buying batteries - as part of UPS - so if you think about it, a lot of "storage" is already in place.

SY - have put up the details for Sanjay to help size. Saw the phillipines video, nice!

Bheema - can you SMS me the number of your contact, let me get a quote from him too. I can send you mine.

 

Bheema.Upadhyaya's picture

Contact details

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The contact details are here. I asked for appointment to visit a wind-cum-solar installation at JP Nagar (RBI Layout). BTW, I will be cycling(Go Green effort) to visit the plant :)

http://www.ecosaveindia.com/contact.html

 

Eco- Save India Pvt. Ltd.
F-3, Aishwarya Apartments.
38, Rest House Road (off Brigade Road)
Bangalore – 560 001
 
Tel: +91 80 41680010
 
Email: solutions@ecosaveindia.com
" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
Bheema.Upadhyaya's picture

Additionally...

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I have sent link  this page to Adarsh of Ecosave to give his thoughts/inputs.

 

" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
s_yajaman's picture

Solar pumps

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SB,

Check this out.  http://www.indg.in/rural-energy/technologies-under-rural-energy/solar-water-pumping-system The 2 HP here is too much.  1/2 HP is about 375W.  You should be able to manage with the existing system.

The other thing is that the simultaneous load will not be more than 1-1.5kW.  It's unlikely that every light and fan and motor will be on at the same time.   Another way to validate - most of our houses have installed loads of 5KW; if all of this were on 24hrs your energy usage would have been 120KWh/day/  But more likely your energy usage will be 10-12 KWh/day.  This means your average load is 500W.  There will be blips, etc.  But you could manage with 1.5KW.  remember each watt costs Rs,150 or so.  

The weakest link in this system will be the battery.  Understand the replacement cost of this. I don't know if you can or want to go completely off grid.  But you could reduce your dependence on it by probably 80%.

Srivathsa

Drive safe.  It is not just the car maker which can recall its product.

sanjayv's picture

@SB - Done deal

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SB, I *promise* to give a you a preliminary sizing sheet and specs this weekend.  As you know, I am not exactly swimming in free time presently... hence the word promise as a guarantee.  I will help you do this non rocket science calculation

The key with solar systems is to find a GOOD vendor - someone who has done a lot of system integration and who will do the homework and proper hardwork to give you a good quality installation.  My very limited experience thus far has not been good.

Now I need two things from you.  I guess I can assume numbers, but then that is no good.

(A) Have you thought of all the loads? Anything else?

(B) How long will each load run (per day)

(C) How many days of the week, if that is relevant.

sanjayv's picture

One more thing

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What is the power rating on all those things ... CFL, Fridge etc.  

Ravi_D's picture

@SB - Motor Loads

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With motor loads (Pump, Refrigerator) you have to consider the starting (inrush) current. Could be 10x the running load. UPS / Inverter systems don't like such inductive loads. I can see why someone would recommend a 4kVA unit to cover for such needs.

But upsizing has other issues. Most solar power conditioners have circuitry to shut themselves down when the load idles below 5% or so. Accuracy of these load sensors vary wildly, and this idle sense could be anywhere between 2 - 8%. @ 8%, a 4kVA unit will shut down if load goes below 300W. And that is around the load you will have with your TV, a fan and a couple of lights turned on, during dinner!

Look for a smaller power conditioner with higher overload capability for a short period (something like 2x overload for 20 sec). 

Ravi_D's picture

Load Computation

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It is best to convert everything to kVA when computing AC loads. Multiply stated load current with 230V. If you only know the rating in watts, divide by PF. 

Most domestic loads are inductive. Adding a PF correction capacitor really helps in improving your efficiency when you are couting every mW. Let us leave that for another discussion.

For starters, you can assume following PF:

  • Inductive loads (Motors - Pumps, Refrigerators, Ceiling Fans): 0.6 to 0.8
  • CFL Lamps: 0.7. I hear the newer ones have PF correction circuitry. Then 0.85 may be.
  • TV Sets: Better invest in newer energy star rated LCDs. Smaller the better. 0.8 
  • Resistive loads (Incandescent bulbs): 1
  • Other loads (Water Purifiers, Computer, Laptop, anything else...): 0.8
Once everything is in VA (or kVA), select all the loads that could be ON ON simultaneousely, and add up to give you worst case load. Give yourself 20% head-room. Should be close.
Ravi_D's picture

Don't forget to add...

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... these commonly forgotton but convinience loads.

Kitchen / Bath Exhaust Fans

Mixer / Grinder (Don't try on Battery power - better to go the traditional hand-pounding/grinding route)

Microwave (Very power hungry when turned ON - same as mixer grinder)

Iron Box (Same as mixer grinder, though you can get away with a small travelling style one)

Hair dryer (Same as mixer grinder)

Washing Machine (Better go with traditional hand wash / or create a job - hire a maid). If you have to have one, buy a front-loading one, and disable the built-in heater

Vacuum (Don't try on batteries)

Air-conditioner (Really?) / Air cooler - Thatched / tiled roof might be a workable option

sanjayv's picture

Sizing - results

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Okay, here are the results from an effort at sizing.  Since you did not give me numbers, I assumed few things.  The friedge is 165 liter.  I assumed hours of operation.

Lights, 15 W CFL, 5 Nos. running for a total of 32 hours in a day (average of 6.4 hours per light).  Here I assumed one light is an outdoor light which runs for 12 hours.

Your 3 fans run for 13 hours total

TV for 4 hours

Water pump for 30 minutes

Fridge 24 hours with a certain assumed duty cycle. I also assumed slightly different numbers for the weekend.

Also assumed that the system is in bangalore and the site is free of any potential obstructions/shadowing.

If all these are AC appliances, you need 6 Nos. of  2x1m crystalline silicon panels.  In other words, 12m2 of total panel area.

Now, if you want 95% reliability which a rule of thumb says that you need 3-4 days of battery storage, then you will need about 14 120Ah batteries for storage.  If you have the grid also available and want only want one day of storage, go with 4 batteries.

Now, the other option is to use dc appliances.  You can have all these requirements running with DC. This avoids the inverter losses.  Many DC appliances are also much more efficient, but hard to find.  I found data sheets for each of these things and did an estimate.

IN this case, you will need 3 Nos. of 2x1m panels. You could probably even manage with 2.

You will need 6 batteries now for 95% availability.

Of course, this is a preliminary sizing.  You have to look for more options for panels, consider issues such as start-up current for loads such as motors.And you need an economic analysis. 

 

s_yajaman's picture

Sizing

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Sanjay,

So an AC load of about 900W - 1KW will be supported from those 12 panels.  Here is a link from Australia on this topic.  Would be quite instructive to go through the comments as they will be real life data vs. predictions and calculations..

Some people talk of getting quotes of $12K (AU) or Rs.500,000 for a 4KW system.  

 http://www.solarchoice.net.au/blog/which-solar-panel-type-best-suits-your-needs-monocrystalline-polycrystalline-or-amorphous-thin-film/

 

Srivathsa

Drive safe.  It is not just the car maker which can recall its product.

sanjayv's picture

Not the right way to think

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Srivathsa,

I wrote 6 panels, not 12, but I have selected larger sized 2mx1m panels.  You can go for crystalline, polycrystalline or amorphous/thin/film panels.  Prices will be a bit different and area requirements will be different because efficiencies are different

These panel calculations were based on some conservative temperature derating and some rounding up and the design is for the worst month of the year (in terms of sunshine - in the rainy season).  So it is a bit oversized.  This number is also based on 5-6 hours of work on a weekend.  I am not a person with extensive solar PV installation experience and with data sheets at my finger tips.  So lot of research was involved.  Like with any system integration job, one gets better with experience.

Couple of points to note:  It is not right to think of solar loads in terms of kW.  My design was built on the average Watts required based on the energy consumption (Joules, not Watts) and the average daily inflow to the battery bank to keep it charged to meet the load in the worst month of year (i.e, the design month).

Rs 5,00,000/- for a 4KW system(based on nominal total capacity of panels) is too low an estimate.  Maybe it includes subsidies available in Oz?

 

silkboard's picture

placed an order

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Thanks Sanjay for the info/numbers. So we have gone with the 4KW system. We paid some advance, had to fill some forms to apply for subsidy. Now waiting for delivery of all equipment, and installation on the roof.

Here is a Link to what we are actually buying. Wanted to avoid naming the vendor, but hard to do that now. Usual disclaimer: I am in no way linked with them, and we are not here to promote any one vondor.

2KW - 6KW Solar Power Conditioning Unit.

Will keep everyone posted on how this goes. Thanks for all the calculations so far.

sanjayv's picture

SB- questions

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I have several questions following your post. Can you share more details?

(1) What is it that you have purchased?  A PCU?  Or a full set of items (panels, batteries ... the whole system)? Normally, a subsidy is offered for a whole system, and not for people buying PCUs.  

(2) They are offering it to you for 1.4 lakhs after subsidy?!  See question (1) and pick the punctuation based on yopour answer

(3) How many and what type of panels are you getting?

(4) How many and what kind of batteries?

(5) Has the vendor seen your house where this will go up? Have they figured out where it will be mounted?

(6) Who is providing the subsidy - MNRE?

 Apologies for all these questions.  In the 5-6 years that I have been practising engineering in India, my opinion of our average engineering services is pretty poor.  There are good people who know what they are doing, but you have to hunt for them.

A well installed solar system will work for 20-25 years with basic maintenance.  A poorly installed one will start giving you problems in 3-4 years.

I wish you good luck.

idontspam's picture

Hey I am still open for

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Hey I am still open for business.. and I still dont have a clue what my load should be :)

sanjayv's picture

What is my load?

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For a solar system, your load is what you think it will be!  Seriously!  I gather your probolem statement is "Can I power my home in Bangalore off solar"?  Answer is  "Of course, provided you match your load to what you can produce!"

So you want to figure out what your load is today?

List every electrical appliance that you use in your home and estimated number of hours.  If there is a substantial difference between weekday and weekend, identify that.  Since all your loads will probably be AC, just list the power rating of each appliance/item along with it.  Type it all in a spreadsheet and send to me or put it in a google document spreadsheet.  Let us start from there.  We will arrive at a load this way.

silkboard's picture

Will post soon

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Sanjay, everyone,

Have taken the plunge, so have no other option but to post all details, pictures and answers. In about two weeks when its all installed and ready.

-SB aka Pranav

srinidhi's picture

wheres the 'like' button?

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super SB..will look fwd for details..

murali772's picture

exemplary exercise in crowd sourcing info

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yes, where's the 'like' button?

Muralidhar Rao
idontspam's picture

Equipment list template

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WIll get to preparing a spreadsheet. Trying to make it a comprehensive list of electrical equipment & not just mine. Will send you over mail soon.

sanjayv's picture

suggest not doing that

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IDS,

I suggest you just pull together your own list - a case study.  There are websites with larger list of electrical equipments.  I am typing something up... will post when it is ready.  It is a lot of work trying to be comprehensive!

silkboard's picture

details of solar system we have bought

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So here are clear details on what we have bought. First thing, it is a 4 KWh system, not 4 KW as I mentioned in earlier comments. Meaning, it can supply 4 units of power during a day. Other way is, that it can supply 1 KW power for 4 hours. I am still confused by the way they put rating numbers (KW, KWh, KVA, KWp etc). Not that I don't get what these mean, but, I don't get things like the simple answer, will this 4 KWh system be able to run a 1/2 or 1/4 HP motor?

  • 1/4 HP motor = 746/4 = about 190 W.
  • Assuming start time surge of 2.5x, we need 190 x 2.5 = 475W
  • So, this 4 KWh system should easily be able to start and run 1/4 HP motor for 15-20 minutes.

Back to the list of what is included.

  • They call it 4 KWh system. And also 1 KW system (perhaps 1 KW is the peak power rating)
  • 4 solar panels, each 3ft x 5 ft = 15 sqft. So total solar panel area is 60 sqft
  • 4 batteries, each is 180 Ah / 12V. Total voltage = 48
  • 1 Inverter like unit, called Conditioning Unit, which has line inputs from Solar Panel, and Grid.
  • Final cost, after subsidy = 1.7 lakhs (raised from their first quote of 1.4 Lakhs)
  • Subsidy comes from Ministry of New and Renewable Energy (MNRE), is about 30%.
  • From what we understand so far, the subsidy is only from the Central Government (MNRE), nothing from State Govt.
  • One more thing they are saying is that you get subsidy only on the 1 KW (or 4 KWh) system. Meaning, if we bought a 2 KW system (twice this capacity), we would not have received any subsidy on the next 1 KW capacity. Not clear if this is true, and if true, why?

So this is it, installation is underway. I will keep updating as I "learn" new things. Except for the rating thing (1 KW, 4 KWh), rest seems clear enough now.

Ravi_D's picture

@SB: A Quick Check

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3 x 5 Sq ft = ~1.5 sq m

Insolance in Bangalore ranges between 4.4 to 6.5 kWh / Sq m / Day. Souce: Link.

Assuming worst case (Month of November), 4.4 kWh / Sq m / Day, and 15% panel efficiency, we get around 1 kwh / panel / day. So 4 panels together shoud source around 4kWh even during low months.

But inverters and batteries come with their own efficiency numbers. Not sure what they are in your specific case, but I'd doubt it is lower than 80%. Battery capacity seems a bit much. 180Ah (@12V) x 4 gives you approx 8.5kWh storage. Since these lead-acid batteries are not typically designed for deep charge/discharge cycles, it is probably done to keep them running in their comfort zone. 

So, for four months in a year you have a bit less than 4kWh/day. A bit more during the rest of the year.

If this is for a dwelling you only frequent occassionaly (say a farm house), you may only use part of your load every day, and a smaller system might do. If this is for your house in Bangalore, you may end up drawing some grid power during the 4 low months.

We will know for sure in a few weeks, right? :)

silkboard's picture

grid is there

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Grid power is there, though reliability is low. Single phase supply is there for 12-14 hours every day. So as long as solar can run the other 10-12 hours, incl some low usage night time, good enough. Planning for 1-2 days entirely without power was a consideration, but that will be too expensive. We are already beyond our budget (upto 3x the cost of UPS).

Let this thing get installed first, will then know all this better. We are hoping that we can add more capacity by just adding more panels. I think that too should be a consideration when buying solar for domestic usage. When pricess fall, or more subsidies get announced, should be able to add more capacity.

idontspam's picture

WHy not to subsidize

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Meanwhile here is a piece on why cost of solar should come down due to demand/competition & not by subsidy. Apparently demand in Germany picked up so much that subsidy started draining the govt.

 

 

Anithasunil's picture

Solar power instead of Generator?

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I am waiting for more information from Silkboard.. Has the installation been done? Photos of the installation? 

Silkboard, Does the cost involve any maintenance contract as well? Do anyone have an idea of the maintenance cycles for the battery? Hw often would it need a replacement/servicing, how much would it cost etc? From a maintenance cost perspective, I am thinking that the battery would be the critical one.

I stay in an apartment with about 350 flats. I would like to do the math for moving from diesel generator to a solar+battery arrangement.  

What the diesel generator backup offers is as follows. Maximum backup is for 12 hours. The diesel generator can operate continously only for 12 hours, and has to be switched off for few hours after that. Power requirement  to power 6 Lifts and lighting in common areas (approx 60 tubelights and 90CFLs), 6A connection for eahc of the 350 apartments, and the water pumps for 6 blocks (not sure about the rating! right now, I would want to go with assumptions here).

As far as I understand, the STP has a separate diesel generator, and the backup system need not take care of the power requirements for the STP.

Can someone help me with the math to understand the approx ratings of inverters, batteries, panels etc, and some approx costing?

 

dr.baby varghese's picture

improve solar electricity

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the solar electricity production could be improved and made more cheap enduring and universal;  if the

indium cells replace the silicon cells and

magnetic semiconductor system replace battery

as storage (visit my bog at praja and blog spot.com)

Dr.Baby

silkboard's picture

Still not installed, plus updates

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So here are more details of the system, things get more crisp as we go.

  • System rating, in the application letter to MNRE for subsidy is 1 KWp. P for peak, system can generate 1 Kw of peak power, so rating 1 KWp
  • We are getting 4 12V, 180 A/h batteries. Total storage capacity would be 360 A/h as we will have two batterie sets in parallel. Battery voltage would be 24V.
  • The Solar Power Conditioning unit is rated 1 KVA, input volage is 24V (matches with battery set I think). I think this (link to PDF) is the Solar box, it basically includes the battery charger, DC to AC inverter and the smarts to pick between grid or solar as the source for charging batteries.

The latest is that they have been late in completing the installation, new date has been given, the syste, should be up next week.

Yes, yes, will keep everyone posted.

Anithasunil - replacing the DG set with Solar + batteries has a few more angles to it, not as easy. I think lets discuss that in detail, with Sanjayv's help (will need him on it), on a separate post itself.

 

sanjayv's picture

Replacing DG set with Solar + Batteries

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@Anithasunil,  That load requirement sounds quite crazy.  It will be very hard to replace all that with solar.  To top it, lifts are a tough load to run off inverter.  Each lift will connect to a different phase and the motor will start and stop intermittently.  Hard to handle. What would be great is if you could have a Hybrid system, where the PV output could combine with the DG output and reduce the load on the DG.  DG power costs some Rs 15 per unit.  So any drop in load would be a direct saving.  I am just not sure what products exist in the market to support such a hybrid application.  Need to search.

idontspam's picture

Batteries vs grid direct

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I think until we can get fuel cells like bloom energy we should have panels feed directly to the grid. 740sqkms of BBMP area translates to 130000 acres @ 4 acres per megawatt & assuming 70% of that area are roof tops we get 32500 MW. If even 10% of them adopt panels we have 3250 MW which is close to 4 times more than the Kaiga nuclear power plant generation. 

Bottom line is 10% of Bangalore can give 4 times the energy of a Kaiga nuclear plant. Market creator has to be the cheaper panel, batteries should be an upsell strategy.

Anithasunil's picture

I understand that it would be

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I understand that it would be difficult to replace the diesel generators with Solar power. But, Hybrid schemes would be good!

Few pointers, which I got, and I was thinking would be helpful in the calculation..

 

It seems diesel generators, when they run on full capacity, the efficiency is much lower compared to when it runs on say 25-50% efficiency..

Also, being an apartment, the Bescom power used falls into the highest slab. So, it might make sense to replace some of the bescom power with solar power, as far as possible.

What I would like is to understand the tradeoffs.. Let me talk to some suppliers, and get their perspective. Will post the updates, once I have some Idea :)

sanjayv's picture

Batteries vs direct grid

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IDS estimates that Bangalore can give 3250 MW power from solar.  Let us assume we can even get 1000 MW from solar PV.  The problem with connecting it to the grid now becomes that this 1000 MW is a substantial portion of Bangalore's power consumption (which generally tops off at around 2000 MW according to BESCOM data). As the sun plays hide and seek behind the clouds , or on a day like today when it was sunny and clear in the morning and is overcast now, it can seriously make BESCOM's job harder.

There are several other grid technicalities that I am not competent enough to comment on.  However, one this is clear.  Here is a source of power. Costs are starting to get attractive  A coal plant costs about Rs 150 per Watt to build (this is based on some numbers that have always been in my head.  I could be off, but doubt if it is dramatically off). Solar PV with inverter will also come at that price.  Panel cost of about Rs 70 per Watt or even cheaper according to some numbers I heard couple weeks ago.  Add inverter costs plus installation etc. maybe you will come in the neighborhood of the Rs 150 per Watt number?  This number was unimaginable just a few years ago.  There is a case for BESCOM to start moving on this and get installed grid connected solar increasing in a phased manner.

Our weather forecasting (medium and short range) is truly pathetic.  I tried using various weather forecasts to plan my solar testing and found out that I could guess the weather better than any forecast.  In the US and in Taiwan, two countries where I have tested it, I found that for the most part, weather forecasters provide very useful estimates.  With some effort there, surely we can get better at this also?  That will help predict solar panel output much better for the grid planners and schedulers.  We have quite a bit of installed hydro capacity.  While hydro is the cheapest source of power, it is also something that can be rapidly started up/ramped up and down. Having that spinning reserve will help manage quite a bit of the solar fluctuations? (Just an educated guess... knowledgeable people feel free to correct me).

Bottom line: grid connected solar has a lot of potential, but there is a need to do your homework while preparing for this.

silkboard's picture

system installed, working!

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Sorry for being away for a bit, busy with some work travel.

So the solar system is all installed and running now. Specs the same as I mentioned in the last comment. Four big batteries, 2 panels, a big bix that can charge batteries from grid as well as panels. Same box also supplies power (from solar directly if battery is topped up already, or grid, or batteries - in that order) to the house.

Have to watch how much load it can handle, and for how long. Will report all these stats in June.

silkboard's picture

eliminating DG, all solar for a community

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@Anithasunil, from what I know of Solar so far, replacing DG set for your apartment with Solar may be too expensive an option.

If BESCOM or KREDL or someone had prebuilt solutions, through partnerships with a few vendors of course, for apartments, that may help. By pre-built solution, I mean an integratd system, for various capacities an scenarios, like

  • 100 aptmts, Solar primary, Grid 1st backup, DG 2nd backup
  • 1000 apatmts, Grid Primary, Solar 1st back up, DG 2nd backup
  • 20 aptmts - Solar + Windmill primary, Grid only backup
  • Single home - Solar + Windmill primary, Grid only backup
  • Single home - Solar ONLY, DC based lighting option
  • etc, etc - think more.

Even if BESCOM or KREDL were to document all such "solutions" at a single website, and circulate to communities through BBMP/BDA/BMRDA, it could at least generate enough interest so that creative minds can get on the job to make the solutions cheaper and easier.

Shall we discuss what all govt can do to push and promote Solar/Reneweable power on a separate post. If the discussion makes progress, let us go meet BESCOM and KREDL separatey on having them do something.

silkboard's picture

So, we have our Solar sytem doing good for a few months now

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... will post pictures and report in a separate post. Here is the Summary

Good experiences

  • 24x7 power (almost - see below)
  • Can even run the 1/4 hp water pump on it, 10 mins, no problems
  • Could get drills and few other tools working on it, saved a lot of hassle for mechanical works because otherwise, the mechanis would have to wait for the grid power.
  • Runs 3 lights, 3 fans, Fridge (see below) and few more things like charger etc, even the rice cooker once - no issues. Yet to have a surge (see below)

Problems

  • Only one. Sometimes, mainly during the evening/night hours (we have assumed this is due to low voltage from PV), when the fridge (its cheap old world fridge, nothing fancy at all - manual defrost) starts its compressor, there is a surge. The system cuts off and restarts itself.

Googled a bit for the fridge problem, looks like this is fairly common situation (temporary current surge).

Over all experience though

  • Good
  • However, at times family feels that a large UPS would have been cheaper and done the job (of surviving 8-10 hours without power). May be yes, but it feels good to have removed dependency on the grid for small needs.
  • Can't remove Grid power though as 3-phase power is required for irrigation pump.

Some of you sent private messages with request to see the system. Sory for being out of action, will check on this and get back.

kamalakar pandit's picture

Hi Silk board..   its really

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Hi Silk board..

 

its really nice to read and know this. I am also interested in setting up solar power, only for CFl lights at certain area...say may be 3 to 4 points.. how much it will cost me ?

Regards

kamal

silkboard's picture

appx 25K

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kamal, roughly speaking, 75W panel, for 8-9K. 12-15 K for battery. Appx 20-25K.

rackstar's picture

LED lamps

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Instead of CFL lamps, now low voltage white led lamps come as efficient alternative. It is cheaper if the whole system works in low voltage DC, instead of converting all to 240v AC, but a parallel wiring is required. It should work out for less if 2-3 lamps are used.

silkboard's picture

posted pictures here

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Here, pictures of our rooftop solar system. will be posting experiences specific to this installation in that new post.

Thanks everyone for the help during the purchase process!

 

Pramila's picture

Need help

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thank you for the informative posts on Solar lighting sanjayv.

Was wondering if  i have your emailid? needed more information on the SPV system in Bangalore.

regards

pramila

Bheema.Upadhyaya's picture

Finally, I have gone solar

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Finally, I have gone solar with following specs.

1.Sinex 800VA/12V/50A LCD Display

2. Luminous Solar Tubular Battery with C10 Rating - 100AH

3. 360 Watts Solar PV Module from HHV (180 Watts * 2 No's) - with a slot for further 2 panels making it 720W.

Expecting installation to happen this week-end or next mid-week. The discussions done here helped a lot.

This installation offers : Normal UPS mode and Solar mode. In solar mode, the system will utilise only solar power even we have grid power, when solar power backup comes to 50% then it will consume grid power. In normal mode, I am told grid power is given preference.

This is in line with my aim to get clean electricity in long run. I am thinking to supplement my installation with a chota wind mill in the slot meant for another 2 solar panels. But thats a long term plan and if technically/financially if feasible :)

And Pranav, how is your installation doing?

 

" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
Anithasunil's picture

Bheema, Can you share some

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Bheema,

Can you share some estimates on the cost of installation as well?

Bheema.Upadhyaya's picture

Around 45k anitha

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Around 45k anitha
" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
pvkay's picture

SOLAR PANELs From China.

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I appereciate feed backs as to the reliability and quality of Solar panels and Inverters/ Control panels etc, obtained from China?

Regards, Vijay

sanjayv's picture

chinese panels

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Nobody knows the answer to the chinese question.  Solar panels have to have a life of 25 years.  If you get the panels from a reputed vendor such as Suntech in  China who do rigorous reliability testing... have no fear.  I have no idea about the other assorted manufacturers there. In fact, you can extend the argument to vendors in India as well.

Bheema.Upadhyaya's picture

Pictures of going solar at my home rooftop

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Here are some pics of our rooftop installation.

" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
silkboard's picture

Hey bheema ...

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sorry - late response. our system is holding good. BESCOM cables keep snapping now and then, and then the solar system saves the day, actually night also thanks to the batteries.

Hey - would you be okay creating a new post with pictures to share your solar system. thinking of creating a solar rooftop showcase section on the site.

Bheema.Upadhyaya's picture

Its in facebook Pranav

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All pics are public and visible. You can share any of them. However, still I am studying my system. I am not sure how it works. That is because, lack of display of meaningful messages in the system. For example, it says "GRID ON", then we dont know, if it is supplying directly the grid power or if its a just info message.

I guess it will takes weeks for me to understand it ;)

" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
Bheema.Upadhyaya's picture

Actual Load Readings from my..

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Actual Load Readings from my Solar System (800VA)

1) Ceiling Fan (6% @min 12% @Max)

2) Laptop (8/9%)

3) 23KW CFL (4%)

4) 60W Ordinary FIlament Bulb (17%)

5) Aircooler (Medium - (14%)

6) 32" LCD TV (10%)

7) 6W LED Light (1%)

8) No load also shows 1% (No clue why)

 

9) UPDATE (6-May) My electric bike of 20AH/48V Battery (23-24% load). Fully compatible. Thus making it real clean energy vehicle.

 

PS: Did you vote? 

" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
Bheema.Upadhyaya's picture

The Hindu has an article

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The Hindu has an article  :

 

"As a sun-swept country, India should have been a pioneer in the use of solar power with a photovoltaic panel on every roof. Good policy can help make up for lost time.

Solar is the most secure of all energy sources, since it is abundantly available in India. With crippling electricity shortages, the price of electricity traded internally touched Rs. 7 a unit for base loads and Rs. 8.50 during peak periods."

 

 

Go to Article

" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
pvkay's picture

Alternative Energy

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There is huge scope of Solar power capture in India. The Governmnt should make it a policy on war footing in this direction; not even solar, but wind, ocean waves, waste heat capture,etc etc, Oil companies  , Railways, Power Plants and other ventures should take initiatives/ research efforts  to harness this power for full use. Germany has taken a lead in this regard.

As the above energy capture has full environmental safety advantage, cost of environmental damage and health issues from use of conventional  mineral oil/ coal  very much outeighs the  utilisation of these alternate resourses.

 

VIJAY

silkboard's picture

thanks, tried the fridge?

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Bheema, yes, voted. Pictures available in a separate post as proof ;)

Quick question - have you tried running refridgerator on Solar?

BTW, we have tried Coffee Maker + Rice Cooker on our 1 KVA system. Want to try induction cooktop next, with power (which can be adjusted in induction cooktops) set to 600W.

Bheema.Upadhyaya's picture

Well, I am advsied not to run

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Well, I am advsied not to run high load items such as fridge, heater, washing machine. However they have told me in case of emergency I can run half HP motor for a while after switching of all other loads. As we know, even though the fridge is of 350W in capacity, when the compression motor starts, the surge goes upto 850W. As mine is small scale installation (still with "sweet" memory of 42K) not daring to experiment :)

But I am told induction cooker with 350W mode( I guess lowest) can run. But how long, question mark!

On negative note: I am not so happy with display system of coz of lack of information it displays. It never shows some crtical parameters.

a) From where its suppying power  (Just says GRID ON)

b) How much is grid volt

c) What is voltage and current coming from PV array ( So we have no clue about Solar Cell Arrays)

 

" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
Bheema.Upadhyaya's picture

UPDATE (6-May) My electric

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UPDATE (6-May) My electric bike of 20AH/48V Battery (23-24% load). Fully compatible. Thus making it real clean energy vehicle.

" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"
archana_sunblaze's picture

Solar power from sunblaze solar

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[MOD NOTE: approving this ad like comment as it seems relevant, and includes some data points]

I was going though this post and looking at this points and cost looks too high.

  • Need about 80 square feet area for 1 Kw worth power
  • Cost for this may be about Rs 3 lakhs
  • Whatever is required to integrate Solar supply with Government grid (BESCOM) so that Solar would be primary and BESCOM only for backup or variable needs exists, and is most likely included in the above price estimates
  • Panels last for 25-30 years.

Once upon a time having solar power at home was very costly,not anymore.

We from sunblaze provide the very efficent systems for domestic and office purpose with best rates in Market.

for 1KW/per day We use 125 W panels and it requirs 1 SQ meter space.

Cost would come up 32,500.Which is the best price anyone can get.We have ran small industries,school labs and few more efficiently.

We are based in banglore and we have head office in Rajarajeshwarinagar

for more details you can check www.sunblazesolar.com or write to support@sunblazesolar.com

Vasanthkumar Mysoremath's picture

Sunlight harvesting - 300 days/year free power

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Many of us misuse electricity during day time when the unlimited source of light is just outside our windows/doors.  Government offices, homes, banks, five star hotels, shops etc., keep burning the bulbs to light up the interiors.  This is an avoidable criminal waste of scarce electricity.  Example; one bulb of 40 vats burning for 24 hours consumes one unit of electricity.  If this one bulb can be switched off by 10,00,000 consumers (out of a population of more than one crore in Bengaluru), we can save that much of electricity units, by adopting simple methods through sunlight harvesting. 

 

India is blessed with 300 days of bright sunshine and is free.  Please have a look at this URL http://sunlightexpertvasanth.carbonmade.com and click on the links to know more about how it is possible for all of us to be a little more responsible in saving electricity.  Example; for generating 1 MW of power, a minimum investment of Rs.1 crore is required.and at this rate, one unit saved is equal to 3 units generated.

 

This idea was a World Bank Project - U-SEE (Unlimited Saving of Electrical Energy) during IDM 2007 and was awarded a certificate of honor with a knowledge grant of Rs.20,000 to this Praja. Former President Shri APJ Abdul Kalam witnessed this demo at World Bank arena on 28th May 2007 and appreciated this grassroots level approach for lighting up homes/schools in rural areas.  I have given designs for different users and can be used without reservation. 

 

Vasanthkumar Mysoremath

9845950440

 

 

 

 

kbsyed61's picture

@Bheema - Size, Cost?

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Bheema,

Could you pls share the details of your installation?

Size of your solar power Installation? KWh?

Cost of equipment?

Cost of Installation?

Subsidy help if any?

Performance so far?

 

--Syed

 

Bheema.Upadhyaya's picture

@syed:   Size of your solar

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@syed:

 

Size of your solar power Installation? KWh? 800VA

Cost of equipment? 45K approx

Cost of Installation? Included in above (But they charge internal wiring extra+cost of wires and other materials) but as I had planned for solar while building home, I had already done wiring from Solar Panel to UPS Setup - So no cost for me)

Subsidy help if any? I didnt opt for that. But they have offers. They business trick is as follows:

If you opt for subsidy, they will charge high as govt provides money. Also govt asking them to maintain the installation for 5 yrs mandatory. So they will add that money in price ! So you can expect cost to go up by at least 10-15K

 

Performance so far? Technically good performance. Financially, I am not bother to gain :) Also unfortunately, my meter broke down during my evaluation. But visibly you can see when there is full solar power available meter slows down !

I guess I have posted photos in my FB page. Link

Hope this helps. If you have more queries, kindly post here. I will try to address.

 

" My mantra to public bodies=> Enable->Educate->Enforce. Where does  DDC  fit?"

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