Karnataka - Rooftop Solar systems for retail usage

This book will hold together interesting posts or wiki pages to share information and personal experiences on rooftop solar systems. The basics are in place, a government organization called Karnataka Renewable Energy Development Limited (KREDL) is already in place. It has funds to promote usage of, amongst other things, Solar Energy. On the other hand, commercial suppliers are bringing more and more Solar rooftop solutions to market. But consumer awareness remains low, high price perception is a barrier, and precise information on what one-time and ongoing subsidies are available for using or generating solar power is not easily available.

On to the informed and enthusiastic Prajagalu to pool together their consumer side knowledge and experience ...

Pictures of rooftop Solar system

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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.

The Solar Panels, four of them.

Manufacturer details, written on the back of Solar panels

Roof Top Solar PV System for residences - my experience

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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.




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

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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.

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

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

Do the numbers above look right?

The two answers I don't have are:

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


SB aka Pranav

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

Solar Systems Connected to the Grid - Rules?

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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

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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.