Pictures of rooftop Solar system

Continuing over from this other discussion (Rooftop solar for domestic needs), here are the pictures of the Solar system we put up at a remote rural location.

Batteries and charge controller, or "Solar power conditioning unit" as they call it

Small display on the conditioning unit, during morning hours. During afternoons, solar reading goes up to 40 or so, proof in the other pic.

Manufacturer details, written on the back of Solar panels

Roof Top Solar PV System for residences - my experience

I noticed some discussions on Roof Top Solar PV System for residences. I would like to share my experience and assumptions.

I have installed a SPV system on my roof top as a back up to grid supply 4 years ago, and is functioning satisfactorily although some improvements in the overall operation of the system is desirable and achievable.

Assumptions first:

1. Renewable energy sources are the future; and solar power has the most advantages;
2. Conventional power sources are fast depleting and getting costlier; social and environmental cocerns with these sources are huge and cannot be ignored any longer. Their real cost to the society is much more than what we see now as electricity prices.
3. In order to make use of SPV systems work effectively, the electricity demand has to be managed carefully.  Usage of heavy duty appliances such as fridges, ACs, washing machines, water pumping, electric iron box, etc should be avoided as far as possible OR carefully managed. My requirement was only for lighting, PC, TV, and cell phone recharging.
4. Some financial risk taking is involved for individuals if we want to hasten the wider use of these renewable energy sources.
5. Living in a village a decent backup for the grid power was necessary for me to be able to use my PC at any time.
6. Also I wanted to demonstrate to otheres (especially the authorities: I demonstrated my SPV system to the state energy minister in 2009) the efficacy of these systems.

Experience:

• a. A system of capacity  [50*2 watts, 125 AH battery, control cubicle (for charge controlling, changing over from grid to solar and vice versa, preference to charge the battery either from grid or from solar, a switch and few indicating lamps), iron stand, testing and commissioning all included] was quoted for about Rs 80,000 in 2008. Warranty of 20 years for the panels, and 5 years for the battery was obtained. I held back about Rs. 10,000 as performance gaurantee. The supplier never asked for this money; so huge must be the profit.
• b. The system is functioning satisfactorily for my uses: CFLs, TV, PC, two small table fans, two small table lamps, and power sockets for charging the cell phoness. System is connected to the AC wiring of the house, and hence the soalr power can be used anywhere in the house.
• c. Once the battery is charged fully (say about 4 hours of sunlight), I can manage without grid supply for one whole day.  Supply changeover from grid to solar and vice versa isgenerally smooth and is almost un-noticeable.
• d. I also have a decent after-sales-service as can be expcted in a rural environment.
• e. Since the system is modular in nature no. of panels can be added; accordingly the cable and control cubicle may also need to be changed.

Observations:

• i) The price for a simialr system has come down by more than 50% in 2012.
• ii) The system can be very useful in most parts of Karnataka including Bangalore. There will be some charging of the battrey even on cloudy and rainy days, but to a reduced extent;
• iii) If we know our load requirements well and are ready to accept small sacrifices SPV systems can provide good service.
• iv) Most residences will not need more than 2 kW capacity fo the system, if we manage the usage carefully
• v) Best usage is to make use of all the solar energy generated during day time; and keep the battery energy only for lights, TV and PC for the night.;
• vi) There can be no doubt that responsible usage of the scarce energy resource we have cannot be compromised. We have to decide whether some of the appliances such as fridge, AC, washing machine, micro wave oven etc. are indispensable.
• vi) Small size water pumping sets should be of problem. Best to sue them during day time.
• vii) Cost of 1 KW SPV system can be less than Rs. 2 lakhs; one has to shop around for best buy. Bangalore may offer many good options.
• viii) Before finalising the buy it is advisable to check with one or two who are already using the system; preferanly consult a professional
• iX) Since the system is modular one can go for a smaller systen to start with, and decide to updgrade depending on one's experience and needs
• x) There can be no doubt with more and more people opting for sush systems the prices will come down further and better systems will be made available.
• xi) Subsidy may be available for sytems of capacity  more than 1 kW; need to very with KREDL, Bangalore and MNRE, Delhi.
• xii) As always the pioneers will have to bear some extra costs and risks; but that is why they are called as pioneers.
• xii) As a thumb rule about 1 kW of SPV can be installed in a surface of 60 Sq. ft. Even if it is 100 Sq. ft per kW it is adeqaute in most cases. A  house built on a 30*40 Feet site can offer a surface of more than 500 sq. ft. Hence getting a minimum of 5 kW of solar power capacity is feasible on most of the roof tops.
• xiii) Installing SPV for a group of house will become little bit more complicated not only in the cost, design and operation, but there may be licensing issues to be considered. some one has to take the ownership of the entire system and may have to get license from the electricity regulator. I am not sure about this and hence need to be checked with KERC, Bangalore.

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

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

Solar Systems Connected to the Grid - Rules?

There have been several reports in the news papers recently about solar PV systems in Karnataka getting connected to the grid and injecting power into the electric grid when they produce more than they need.  Today's Bangalore Mirror had a news item (click here) about a city resident who claims to inject power back to BESCOM.  Though he claims that it is done for free, if the power goes back through his meter, he may actually be getting a rebate by having the meter run slow or even backwards, something known as net metering. The discussion in Praja on SB's blog earlier on this topic can be found here.

BESCOM MD, Mr. Manivannan is quoted as welcoming the move whole heartedly, though his actual quote expresses reservations on the issue. The quote is reproduced below.

"P Manivannan, managing director, Bescom welcomes the move whole-heartedly. “I think the trend is slowly picking up in Bangalore. At a time when we are facing enough power-related problems, this is perhaps the best way to get the quantity of power you require. However, when it comes to supplying generated power back to the Bescom grid, there is a problem as one cannot guarantee the same quantity of power on a 24X7 basis. The fluctuation in supply to the grid affects other customers as a specific load will be allocated to them. Further, you cannot compel the owner to limit its consumption to a certain level.”

This story brings up several important issues that needs to be addressed.  The price of solar PV has dropped sharply and continues to do so following several factors, such as glut of polysilicon raw material in the market, entry tof chinese manufacturers in this area, economic slowdown and withdrawal/reduction of subsidies and benefits in European markets.  This makes it increasingly cheaper for people to buy panels for their use.  However, when such systems are connected to the grid and actually push power back, several precautions need to be taken.

As Mr. Manivannan clearly notes, power is available from solar systems based on when the sun shines.  So matching load and demand can become a problem as number of such systems increase.  The grid is now maintained through a very carefully performed process of load forecasting and having power generation or putting in for buying power so that sufficient capacity is always available to match the demand profile. When there is a mismatch, you have load shedding. Solar and wind systems make power when the sun shines or the wind blows.  However, there also other issues that need to be kept in mind when people connect their solar systems to the grid. Some of these factors in brief are as follows.

1. Limit on single phase generation: If there are many such micro generators (as we can call small solar PV panel installations) and their supply is not balanced among the phases, the network can become imbalanced.
2. Generation quantity limits - The power generated should not impact the voltage beyond a limit and the generated power must be within limits of the load sanctioned for the installation since wires are sixed accordingly.
3. Occupational safety:  Clear standards need to be defined and safety precautions in place so that in the event of a network outage or undervoltage issue or power being shutdown for maintenance, there is no power fed back into the grid through the PV.  This can cause serious disruptions or even cause injury or death to maintenance staff. THe system operator (BESCOM) must be aware of all microgeneration installations in an area.
4. Quality of electricity:  There are strict criteria so that having multiple generation sources does not impact the quality of electricity available in the grid. This includes the issue of harmonics (distortion of the Sine wave AC signal) and EMC (ElectroMagnetic Compatibility) requirements.

Going by the reports in the press, it is important that BESCOM look into framing rules for such installations (not sure how easy it is or if BESCOM can do it independently without involving the KERC and other bodies) and to notify the public that such random ad-hoc installations are not allowed. The BM article certainly made it sound as if it is not a big deal to plug your solar panel back to the grid.

Discussion on Praja itself on this topic has been around making a neighborhood micro-grid which then interfaces to BESCOM supply.  All these are good ideas, although there is a need for standards, suitable equipment and more studies on such concepts.  The grid operator and the grid itself will also have to get a lot smarter as the number of such installations increase.  Currently, I suspect we have sufficient generation deficit that a solar system that produces power probably has not much of an impact.  

However, in countries like Germany where generous laws have led to massive number of installations, the traditional power plants have to adjust to compensate for the variable production from these generators.  Such a situation can impact the Plant Load Factor (PLF) and thereofre the profitability of the traditional generators.

Overall, a complex topic that will not fit into one blog post, but there is a need for our utilities to get proactive to specify rules and plan for such approaches.  Currently, we have massive power generation deficits, encouraging microgenerators may be a good idea and the impact on the grid may be small (somebody needs to do a proper analysis).  However, it is important to plan further along to the future and start framing rules and planning now for a situation where there are large number of microgenerators that can impact the overall grid performance.

Disclaimer: Since this topic intersects with my professional interests,  and I am not allowed to speak for my company on any public forum, all the discussion in this post is based on material available in the public domain and opinions expressed here are my own.

Solar power - rooftop, grid-connect, community grid, 3 diff things

Sanjay and IDS are already at it on another post (Solar - connected to Grid). Sorry guys, keep it on there, but I thought a primer on slightly varying type of talks on the subject may help. There seems to be a need for incentives, policy push and awareness on these three types of scenarios. These are from citizens (retail consumers of power) perspective.

Scenario #1 - Rooftop Solar, standalone individual use

Simplest of asks here. What all to buy to go solar power for my domestic needs? Is it possible at all to go BESCOM/Grid free? Likely answer is no, but what all I will not be able to run on solar - water pump, water heater? Will the system automatically take extra power from BESCOM/grid when the load is high? What subsidies are available, and who would provide them? BESCOM, KPCL or KREDL, or some other agency? Will I have to claim subsidy separately (deal with govt again, bribes!?), or will this be given to me at source (from the manufacturer where I would buy solar equipment)? Also, I already have a UPS system with batteries, will I be able to reuse them?

People in urban areas who would buy UPS may give Solar solutions a close look if above information is easily available. People in rural areas who don't mind paying a bit extra to get 24x7 power would also be in audience for these questions. These folks may not do it for cost saving reasons, but are important early adopters.

Scenario #2 - Rooftop solar, sell to BESCOM/Grid

Add to above the concept of feeding surplus power to the grid. How much can I save on my electricity bill? Would I have to buy extra equipment to feed back to the grid? If yes, then how much extra cost? If I am connected to the grid, will I still need batteries? Does feeding to the grid get me extra subsidies?

People who may see Solar for cost reasons would be interested in these questions.

Scenario #3 - Rooftop solar, join a community grid

Take Scenario #1. Add to that the possibility of pooling surplus power through a ultra-local community grid. With such pooling, will my community be able to save money on running DG Sets? Will my community still need DG Sets? Will there be extra subsidy for the community if we pool and go solar, and sell power together to the grid?

This is for Urban areas, apartment/housing communities. It may be easier to install panels on the roof of apartment buildings, and then share solar power. For many apartment communities, standalone rooftop may not be the option at all. If Community Pooling Solar can be comparable in costs to buying and operating DG sets, this could be the way to spark mass-adoption of Solar.

Any more scenarios!? Idea is to separate these by audience or need.