I found this website article that dumbs up calculating solar energy cost [http://www.solarpowerauthority.com/archives/2008/01/how-much-does-it-cost-to-install-solar-on-an-average-us-house.html](Jan 30, 2008). To see if I can simplify this further consider the following.
Simplest: installed cost = $9 per watt. 1 watt continuous use/supply would be equivalent to .73 kWh per month. Because the panel will only be producing when there is enough sun, expect 1/6 of that .73kWh to reflect on your monthly bill (.12kWh). Now, find your cost per kWh for your highest bracket. Multiply that number by .12. This represents your monthly savings per watt of solar energy. divide $9 by your monthly savings to see how many months it will take that solar energy to start paying for itself. The article crunched some numbers to 20 years.
Here's the real kicker. Consider opportunity loss. Roughly, this engineer is saying $9 pays $0 dollars (breaking even) over 20 years ($0.0375/mo) and $9 (paying it back) over 40 years. Let's use a $20,000 system that would render $83/mo (assuming you pay cash and have no interest payments eating up any of those savings). It will take 20 years to pay itself off, then another 20 years to return the investment.
Contrast that with this. Assume I put $20,000 into my savings account (note that savings accounts have horrific APY's) and withdraw $83 dollars per month. It would take 24 years for the solar panels to start out performing my savings account. If I do that same with six 182 day CD's it will take 26 years for the panel to out perform the CD's.
I have not found any data suggesting that a solar panel will last longer than 24/26 years. As such, by the time they start out performing meager savings plans it is time to begin all over again.
The number one down side to this is that your money will always be tied up with the purchase of a solar panel. If the money is invested very conservatively, it will always be there for an emergency.
The upside to solar energy is that there is buzz that the installed cost per watt will reduce to $2. now out performance time is closer to 4.5 years and 5 years, respectively.
Another down side is that solar energy may only provide up to 1/6 you energy as discussed above. Otherwise you must invest in batteries - a serious environmental issue.
The final upside is knowing that you are stepping up to the challenge to be more green.
Please, let me know what you think about these numbers.
