Gall’s Solar Home
This webpage provides some information on the solar cells on our roof. We got them installed in summer 2007, and they work very well. Our electric power meter runs sometimes forwards and sometimes backwards, depending on if the sun shines or not. Over the year, we expect that the system will provide just about as much electricity as we need, so that the electric portion of our power bill will be the $0. That is actually not fully true, we still pay the $16/month (as everyone else) for being connected to the grid.
The 3.78 kW system consists of 18 PV
modules (210 W each) from SunPower
and a small inverter box in the garage. The array is 24x10 ft2 wide
and covers about half of our roof that is facing south. It was installed by Renewable Power Systems, LLC
which was handling all technical aspects as well as all paperwork. The system
produces ~4400 kWh per year.
Cost
|
Total cost (including all permit fees) |
$33,917 |
|
NYSERDA PV Incentive ($4/watt) |
-$15,120 |
|
Federal income tax credit |
-$2,000 |
|
NY-State tax credit |
-$4699 |
|
Net cost: |
$12,098 |
Savings on electricity bills:
4,400 kWh x $0.15 = $660/year. That is, with constant electricity-cost and no interest on the capital, it would take 18 years to get even, and from then on we’d make money. Naturally, it’s naïve to assume no interest and no increase in electricity cost. With a 5%-interest rate, the saved money would just about pay the interest, then as the cost of electricity increases, the saved money would start paying down the capital investment, with some chance to actually ultimately get positive. In conclusion, there is a chance that this system is financially a good deal, but this is not at all guaranteed. However, it’s clear that it has a positive impact on reducing CO2 emissions and on conserving fossil fuels.
If you are interested in any aspect of our PV system, feel free to contact me at galld@rpi.edu, or to look at some other websites as those of my work colleagues Prof. Barb Cutler or Prof. David Borton, or at some solar energy sites like those of NY-State, a site summarizing tax-incentives, the site of the American Solar Energy Society, or the National Renewable Energy Laboratory.
Some data:
First year (Aug 07 – July 08): 4580 kWh
