"Each community solar panel costs $930. Each community solar panel will generate an estimated lifetime savings of $8,331.
What is the size of the panels? You can usually find specs from the manufacturer, but around here most panels cost something like $500-600 each and (for new panels) are rated to something like 275W. The rest of the cost is installation, which is usually 30-50% of the total cost for a solar install and I'd expect the lower end of the range for a dedicated community array. There is also some cost for the inverters that convert the solar DC into residential AC, but on a large community array they're probably using industrial inverters and the cost per panel shouldn't be more than $50.
The next step is to look up the production for a panel of that size in your location. The link posted above to PVwatts is a good place to check, but there are others online as well. They account for you latitude and local weather and panel efficiency to determine how many kWh you can expect from a given panel at a specific location, over the course of a year. Here in Washington, a 275w panel is expected to produce about 280 kWh of electricity annually with only a tiny fraction of that in Dec/Jan when it is typically rainy and the sun is only up for eight hours per day. Most of it comes in the sunny summers.
Once you know the expected production, multiply it by your current or projected energy costs over the lifetime of the panel. So if they're warrantying a 275w panel for 25 years and your power costs 10 cents per kWh, I'd expect 25*28= 7k Kwh times ten cents per Kwh is $700 in savings. That's a far cry from the $7401 you mentioned.
Big numbers like that $7401 are usually the product of government incentives, and Colorado has some of the best ones. There's the 30% federal tax rebate, plus a variety of state and local incentive programs (check out
http://dsireusa.org/incentives/index.cfm?re=0&ee=0&spv=0&st=0&srp=1&state=CO). Without them, the payback on solar panels is usually between 20 and 30 years unless you have very expensive electricity rates like Hawaii or California.
So I'd ask if you will qualify for the 30% federal tax credit, or if they're taking that credit and rolling it into your purchase price. I'd check your current utility bill to see what you currently pay for power. I'd check your local incentives very carefully to make sure you understand what programs their using, and whether that money flows to your community group or to you personally, and whether it comes from the state coffers or from the utility company by way of tax breaks.
In my case, my local utility company writes a check to residential solar system owners based on how much my roof produces. The utility company gets a tax break equal the size of the check they write me. And I have no city or utility-specific programs, so my case is probably simpler than yours.
