Analysis of Rate of Return on a Solar PV System

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The following example was contributed by Steve Fennell of the Saco Solar Store:

In Maine, a 2,000 watt solar system will conservatively generate approx. $445/year in CMP dollars at today's rate of approx. 16¢/kWh*.

Maine presently offers net metering which will offset your cost by an amount equal to what you generate. This would mean you either use the power or build credits if you're overproducing. The credits need to be applied within a year to your CMP bills.

If you spent $10,000 for this system you would qualify for a tax credit of $3,000 (30%) and a rebate from Efficiency Maine of $2,000 ($2/watt or $2,000 max). Your out of pocket expense in the end is $5,000.

We don't know of any “safe” investment these days that would pay you back $445 annually on a $5,000 investment. That represents a simple Rate of Return of approximately 8.9%. Pretty respectable.

The savings become even more profound after the system has paid for itself. None of the above rate of return includes an allowance for inflation of the CMP $/kWh rates.

The systems we’re installing come with a 25 year warranty on panels and electronics. These components will last well beyond the 25 years.

We’ve analyzed a 2,000 watt system for starter numbers to work with. Installed PV prices are around $5/watt. Given the same variables for the location (pitch, orientation etc.) the numbers will closely prorate. i.e. a 3kW array will generate about $668, a 4,000 watt system will generate about $890 etc.

If nothing else, solar makes sense from a home improvement standpoint for resale attractiveness. Solar PV has no moving parts, and little or no maintenance. Homes with properly designed and installed solar energy sources will sell faster at a higher price than one without.

Total estimated cost of a 2kW PV System: $10,000
Maine Efficiency Maine Rebate: -2,000**
Federal Tax Credit: -3,000***
Total Actual Out-of-pocket: $5,000

* Total estimated CMP cost per kWhr (supply & demand) = approx. $.16
** EMaine rebate = $2.00/watt, $2,000 maximum - see:
*** Federal Tax Incentive of 30%:
PV output estimating see:

Thanks to Steve Fennell of the Saco Solar Store for this contribution.  Do you have an example to share? Put it in the comments below or email it to us.