The US government offers a 26% investment tax credit for residential and commercial installations (through the end of 2020). Five-year accelerated MACRS depreciation is also available to businesses that install renewable energy systems. Consult your tax advisor to discuss your eligibility.
In California, solar electric systems are exempt from property taxes. (CA RTC, Section 73) Although the value of your home or business will increase with the investment of a solar electric system, property taxes cannot be raised.