I'd like to chip in a bit more to the forum, and here is something I've been ruminating about: You probably have seen various reports in the media that have mentioned that solar electricity is becoming cheaper than grid energy in many places; with a 30% federal tax credit and some local incentives, that seems plausible.
So it's nice to save the environment and all, but saving money is even better. Here is what I came up with for my situation in VA (no state rebates unlike other states):
Cost of electricity: $136/month (mean of 1187 kWh/mo over 4 years, with a %RSD of 47% as fluctuations from summer to winter are big). Per some installers, I'd need a 10 kWh system to cover my consumption. The system is tied into the grid with a net metering system so that power fed into the system counts as a credit to me during the day/summer. The goal is to offset the solar generation with consumption to have a "net" bill of $0.
Cost of 10 kW solar system $25,000
Less 30% tax rebate $17,500
Annual "savings" $135/month x 12 months = $1620
Add annual incentives from utility at ~$40/MWh = $640, total "savings" =$2420
So not even counting accumulated interest, this should take about 7 years to repay itself.
The big question is opportunity cost so the question is whether cleverly investing $17,500 will make me come ahead or not. One has to then take into account electric inflation (which will probably (?)) remain low, that said my yearly average electric cost cents/kWh has increased by 4% from 2011-2014, with the biggest jump last year, so buy going solar, I'm effectively locking in today's rates for the next 30 years (anticipated lifetime of system, has 25 yr warranty). There also is the appreciation (how much?) of the home value should I decide to sell early.
Here the cash flow estimator from one bid (a high one).
So, on a quick back of the envelope calculation, unless I make a screaming investment elsewhere, this seems to be a good deal?
Please poke holes in my reasoning, or if you have experience, chime in! Thanks!