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

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Written By silkboard - 20 April, 2010

Bangalore Power Renewable Energy Need Help environment Solar 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

I am stuck on figuring out

idontspam - 4 April, 2012 - 13:15

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

finally, got it - its called solar power conditioning unit

silkboard - 3 April, 2012 - 04:34

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.

Storage is primary

Naveen - 3 April, 2012 - 07:24

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.

great! Sanjay, help me size and buy please

silkboard - 4 April, 2012 - 14:09

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.

I am seriously planning for alternate energy

Bheema.Upadhyaya - 4 April, 2012 - 12:30

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

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