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Solar Systems Connected to the Grid - Rules?

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Power

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.

Comments

idontspam's picture

KERC & BESCOM

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To a question on what bescom is doing towards grid tied solar power, on a different forum, MD Bescom stated "The idea makes sense, and already being examined by BESCOM. Last year we have recommended to the government that 50% of the street lights shall be solar powered. Policies are made by the government, and not at BESCOM level. We are just a utility, a limited company, whose shares are held by the Government. So, we cannot take such unilateral executive decisions on whom to supply power and whom not to. Our functioning, and conditions of power supply are closely regulated by the KERC. Yes, we can, and we will submit our opinions before the KERC and Government, by mid of the year. "

sanjayv's picture

MD Bescom statement

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Thanks IDS.  I also stumbled upon that page, coincidentally a little after making this post.  It looks like there is some stuff happening on the grid tied solar regulatory scene, but there is not much information available in the public domain yet. 

I wonder what it takes to enable such a change?  Do we need a notification from the CERC, or can KERC independently put out rules provided that certain grid parameters are maintained?

With our current power deficit, I suspect that we can easily integrate a substantial capacity of grid tied PV before other issues come into play.  The way prices are going, this is a good time to do this.

One point I forgot to emphasize in the post.  The story of this one person casually connecting his PV system to the grid is scary.  There are safety related risks.  So it is important for BESCOM to keep an eye on this.

idontspam's picture

Crowdsourcing solar power

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It is criminal to waste all the sunlight we get, perhaps a concept note on how retail generation has been handled across the world & how KERC/BESCOM can utilise crowdsourcing of solar power will be a good start.

Naveen's picture

Power Storage

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APS Testing Energy Storage System in Arizona

“Energy storage can make renewable resources more reliable for our operations teams and for our customers. One of the busiest times on our system is between 5 and 9 p.m. That’s when many customers get home from work, turn on the lights, the TV and the air conditioner. However, by that time, solar systems have largely stopped producing for the day. With storage, we can gather solar energy during the day and dispatch it in the evening, when it provides the greatest benefit to our customers.”

 

Finding ways to store solar power is the real key. Unless there's a 'revolution' wrt power storage, we will continue to face shortages whenever more power is needed, such as the summer months or late evenings each day. Fortunately, efforts are already on in this direction

Other related links :

http://planetforward.org/...

http://www.economist.com/...

srinidhi's picture

questionable efficiency

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The power generation effieciency for commercially available solar panels these days have not gone more than 20%..so this translates to large farms needed to generate little power..

Also 5 Lakhs sounds way to high initial cost considering the ROI one can expect..and its Chinese pdts..what abt maintenance?

 

sanjayv's picture

cost etc.

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@ Srinidhi - 20% is optimistic with a Silicon panel. For the cheaper polysilicon panels, 10% is a better number. CPV record stand at 44% though, but economics are not in its favor yet.

The Chinese panels are fine.  Nobody is complaining so far.

There is still some way to go before the economics are in favor of solar PV, but at the rate it is going... Current cost by my guesstimate is at some 1.5-2 lakhs per installed kW (this includes panels, mechanical support, inverter, batteries) - without subsidy.  Not bad considering it was close to 5 lakhs per installed kW few years ago.

Major maintenance in our conditions is cleaning dust accumulated on the panels, and any battery maintenance.  Life would be expected to be 15-20 years for the panels, conservatively.

@ Naveen - storage is a key.  Everybody is working on it. No miracles yet!

@ IDS - Why should we invest time on writing a concept note?  There is tons of information in the public domain and lessons learnt in various countries.  If somebody is serious, it will not be too hard to pull together standards.  Is best done by a person who understands the current grid situation, demand curve etc. and has access to good current data.

My understanding from enquiries over the past couple days is that  BESCOM, KERC is working towards grid connected solar and that something concrete is expected in about a year's time... 

 

blrpraj's picture

killing 2 birds with one stone

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If the problem of power and water are solved then that is 50% of the battle won in major housolds so that a day to day battle need not be fought for these 2 basic necessities.

Now, water is abundant in the form of Ocean water but is prohibitively expensive to desalinate since one of the main reasons is that it is power hungry apart from the costs involved in building the plant itself, so this is where solar power can be harnessed. I think solar power can be used in a big way to solve multiple problems. Even oil rich gulf countries are forward thinking and investing wisely in the future

http://www.greenoptimistic.com/2011/01/22/arab-emirates-solar-desalination-system/

http://gulfnews.com/business/general/solar-desalination-plants-in-abu-dhabi-to-curb-water-production-costs-1.968391

India has great talent in terms of best scientific and business minds but sadly lacking a sound policy at the government level.  Solar energy is the greates untapped natural resource in my mind which is the key to solving a multitude of problems if used effectively

- transportation costs (solar powered buses & vehicles)

-pollution (solar powered autorickshaws)

-water (solar powered desalination plants all along the coast with water being piped to interior cities like Bangalore)

-power (already demonstrated in this thread; we can effectively do away with the problematic and unreiable grid in most cases)

I think India should emulate Brazil's success in energy self sufficiency!!  We have great talent but lack of direction and discipline as usual.

idontspam's picture

Self sufficiency on solar

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Taking self sufficiency as the first step, it would be interesting to know how to get ourseves self sufficient on solar power. What is the kWh/voltage ratings we should be going for? what type of solar panel? etc

sanjayv's picture

self sufficiency on solar - how to

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IDS - 3 line question, but answer has to be multi page.  Here is the short version.  If you want self sufficiency using PV (a) You have to go through an exercise to figure out what your load is and how to minimize the load (b) Since solar output will not match your load, storage - batteries- are necessary. Invariably, you may run into a period in which solar can just not match your needs.  Here is where sizing becomes important based on what reliability you need. (c) What kind of panels - there are few options, buyt I suspect current economics will point you to polycrystalline silicon. Maybe a case study will help.   A superb reference if you want to go through the exercise is "StandAlone Photovoltaic Systems: A Handbook of Recommended Design Practices" published by Sandia National Laboratory (New Mexico, USA). Even though an older publication, it is as applicable today as the day it was published,  You can download it for free from the Sandia website (sandia.gov), but somehow, I am not able to open it now.  Here [1] is a copy on scribd.     [1] http://www.scribd.com/doc...

Updated:  Here is the actual Sandia link to a good quality PDF

idontspam's picture

I didnt want a short answer

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I didnt want a short answer :) lets tackle (a) how do we figure out what our load is? we may need an excel sheet to simplify the calculations from the pdf. people can input the number of each appliance & the sheet will multiply & churn out what the load is. 

silkboard's picture

Rooftop solar basic setup, separate post?

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Sanjay, IDS, how about we keep this post for technical and policy related challenges for two-way grid interconnection

  • My Solar system feeds surplus to grid
  • Takes shortfall from grid
  • Adjustments happen in a single bill
  • As a boost to solar, grid could buy solar power at higher tariff, I may, at times get a "negative" bill (I get money from *ESCOMs)

The first step, or basic rooftop solar setup itself is not clear to potential consumers. Let us share our experiences in a separate post?

I will put all recent Solar Power posts under a book, so that they are visible under Gyan.

silkboard's picture

On solar tariffs

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To understand the confusion on tariffs expected from the Grid if I feed Solar power to it, see this Renewable Energy Policy available on KERDL website (http://kredl.kar.nic.in/R...)

In this document, go to page 19, find these three sections.

10. (iii) Feed in Tariff: Various sources of Renewable Energy power procurement by the Energy Supply Companies/distribution licensees will be at Tariffs as determined by the KERC. When plant completes 11 years have to sell power to Energy Supply Companies on Tariff based on variable cost subject to KERC norms.

Next

10. (iv) Solar Tariff: KERC has determined a Tariff of Rs. 3.40 per unit. The Ministry of New & Renewable Energy (MNRE) Government of India supported Solar Grid connected Power projects of 1 MW and above. MNRE has allowed an incentive upto Rs. 12 per KWh for Solar PV and upto Rs. 10 per KWh for Solar Thermal projects in addition to the Tariff allowed by KERC. Under this policy Solar Grid connected Power projects will be encouraged as per the above policy of the Ministry of New And Renewable Energy.

Then next

10. (v) Roof Top Solar Tariff: The Roof Top Grid connected solar KWp level projects of 5 KWp to 100 KWp will be allowed connecting at 415 V, 3 phase, 11 KV level of distribution system of the licensee in such a manner that the maximum energy injection will not be more than 70% of the consumption from the distribution licensee‘s source by the Solar Roof Top consumer. Any injection in a billing period exceeding 70% of the consumption will be treated as inadvertent and will not be considered for commercial purpose; neither the deficit is carried forward to next billing period. Such injection will be settled on Net Basis with the consumption of the said consumer from the distribution licensee’s source in each billing period. Roof Top Grid connected solar power quantum fed to the Grid will be eligible for a Tariff of Rs 3.40 per KWh along with Net Metering facility. If any incentives available from Ministry of New and Renewable Energy Government of India, it will be passed on to the Developer. However, Roof Top systems will be additionally eligible for any other subsidies extended to the Roof Top Projects. Solar Photo Voltaic systems below 2 KWp will be battery backed isolated stand alone systems. Isolated Solar Photo Voltaic sources up to 200 KWp will be for Rural Applications.

Number you get is 3.40 per unit, plus this hazy thing "any incentives available from Ministry of New and Renewable Energy government of India".  And in recent news reports, we heard Rs 8 or Rs 16 per unit.

idontspam's picture

Community grids

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Instead of feeding to the grid by individuals, we can have community pool in for storage & distribution based on their own solar meters. This way the solar grid is isolated & run seperately & can be integrated to the mainstream grid via community when they meet minimum requirements. Power purchase agreements can then be with the community instead of with individuals to reduce complexity & risks. Where there is no community it is possible to invite intermediaries who will have PPA's to buy from individuals.

idontspam's picture

BESCOM & solar

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Bescom, in its letter to KERC, has stated that neither the Ministry for Non-Conventional and Renewable Energy nor the State government has formulated any clear-cut policy for the LT grid interactive solar photovoltaic projects below 5 kWp (kilowatt-peak units). The letter says that the proposal of Ravishankar was considered in order to encourage solar photovoltaic projects.

Source

sanjayv's picture

Grid Data!

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Take a look at the BESCOM Load curve on 11 Jan 2012 posted here. Clearly, the Bangalore Metropolitan Area shows a clear peak between 8-10 am (Water heaters? ACs cranking up in offices?).  The next evening peak is between 4-8PM with a 300 MW demand drop off in between,

Karnataka's generation and purchase for that date can be obtained from the KPTCL website here. (Sorry, I tried to copy paste data, but it was not coming our cleanly).  What intrigues me is the large number of hydro generators.  The thing with thermal plants, especially coal and nuclear is that they are base load plants.  They cannot be started up and shut off easily or operated easily at part load.Once a unit stanrts, it is going to provide that amount of power.,  Hydro is much more flexible.  So it looks like we can easily add a lot of grid connected solar and compensate the extra generation on a sunny day by tamping down hydro production, at least until there is a good way to forecast generation from solar sources.

The question now is how to incentivize grid connected solar without breaking the back of the ESCOMs?

 

Commander V Joshua's picture

It will help the enteauprener

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It will help the enteauprener as well as the power situation if BESCOM can publish clear guide lines on private persons/enterprises connecting solar generated power to the grid. Even if a few thousand MWs of power is generated through solar power plants(though currently only a miniscule of it is being produced), the country will still be woefully short of power.

If properly encouraged and incentives are offered, many may undertake the generation of electricity through micro/mini/mega solar power plants. As of now, unless the investor gets Rs 8 to 9 per unit produced through SOLAR, the project will not be economically viable.

If sufficient power is generated by solar power plants and grid connected, the industry can be given sufficient power during the day and the house holds can get un-interrupted power 24x7. Conventional power producing plants may not get affected in recent years to come.

gampi1969's picture

Plain land - is it possible to install solar and supply to grid

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In case one has agricultural land, whether solar could be installed and can the power be supplied to KEB?  Where do I get this information?

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