[red-beard]

If you want the solar to pay for itself, you need to think of one of a few directions.

1) You have net metering - Buy the maximum that will fit on your roof. Make as much power as you can because with net metering, everything you produce goes against your usage. You are trying to produce enough energy to zero out your yearly usage.

2) You don't have net metering - Minimize the system. Just enough solar to take the edge off your summer bills with the AC running. You may end up with only 3-5 kW, but it will help with the summer maximum bill.

For me, I have enough roof to do #1, but I have to sign up for a 20+ cents per kWh plan to get net metering. This means if I do not cancel out my entire bill, I pay double for the electricty I buy. This is the reason a lot of people in Texas do not get the savings they think they should get. The solar companies calculate the bill with net metering, but either they don't sign up for that plan or they can't put enough solar on to zero the bill.

Example, people install 7 kW on their roof and sign up for a 20 cent per kWh plan instead of a 10 cent plant. They cut their net power consumption by 30%. But 70% that is left they are paying double. The net effect is paying 40% more for thier electricity! You have to understand your power plans and how solar will play with it. And I can tell you for a fact, most of the solar companies will not properly explain this.

One other way to work the solar is with a tiered rate system. In Austin, they do not get power plan choice. And they have a tiered system. The more you used, the more you pay per kWh! Progressive rates. The best way to make solar work is to install enough to cover the top tier. This way, your solar is "worth more" and they pay off is quicker.

Understanding the savings is complicated. And I agree with Red 928. Make your home more efficient first. Add lots of insulation. Chnage windows. Get gas appliances to replace electric ones for hot water, home heating and cooking. Reduce your consumption, then get some solar after your educate yourself on how it will work with your local electric plan.