California solar proposals
Ask for two cash quotes for the same rooftop solar setup. Compare what storage adds to the price, what it changes on your utility bill and what it can power during an outage.
Compare the two options
Use the same panel count, DC size and roof scope. Ask the installer to itemize the battery, backup controls, any inverter change and related electrical work. If the solar equipment changes too, ask how much of the difference is due to that change.
Ask for the estimated first-year utility bill for each option using the same household usage data. Check which rate plan and export credits each quote assumes. Ask for a second estimate with the reserve and operating mode you plan to use.
Most grid-tied solar systems shut off in an outage. For the storage option, ask which circuits the quote actually covers, whether the system can recharge from solar when the grid is down and what happens if the battery runs empty.
Under the Solar Billing Plan for PG&E, SCE and SDG&E, export credits vary by time. A battery can save daytime solar energy for later, when buying power from the grid may cost more. Ask which plan applies at your address and how the projected bill changes when more charge is held for outages. The CPUC’s Net Energy Metering and Net Billing guide explains how the credits work.
If you already have solar and want to add a battery, give your installer your current tariff and interconnection paperwork. Ask the utility how the proposed change would affect your existing arrangement before relying on a new bill estimate.
Ask for usable energy in kilowatt-hours (kWh) and continuous and startup power in kilowatts (kW). The energy figure helps estimate duration. The power figures tell your installer which appliances can run or start together. A whole-home backup configuration still has output limits.
Could you send a solar-only cash quote and a solar-plus-storage cash quote for the same array? Please itemize the battery, controls and electrical work. Which circuits would have backup, how long could they run, and can solar recharge the battery with the grid down? Please show the expected first-year utility bill for both options and identify the rate plan, export credits, battery mode and reserve used.
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