solar calculator — enter your ZIP code and electricity bill, and it returns your recommended system size in kW, the number of panels, the roof area you need, the gross install cost, the annual savings, the payback period, the 25-year lifetime profit, and. The all-in-one U. The California Public Utilities Commission (CPUC) recommends that solar providers give out this guide during their first contact with potential customers. Version 4 of the. Investments from the U. You may be considering the option of adding a solar energy system to your home's roof or finding another way to harness the sun's energy. While there. A Solar Power Purchase Agreement (SPPA) is a financial arrangement in which a third-party developer owns, operates, and maintains the photovoltaic (PV) system, and a host customer agrees to site the system on its property and purchases the system's electric output from the solar services provider. By installing solar panels, you can generate your own clean, renewable energy, reducing your reliance on the grid and lowering your electricity bills. 95 kW solar panel system to cover the average electric bill in California, which will cost you about $21,536. Some states, towns, and utility companies offer incentives that can help lower the cost of solar.