This guide is independent general information. It contains no invented testing or customer-review claims. Product suitability and installation requirements depend on the property.
Create one baseline
Collect at least 12 months of bills or interval data and separate kWh, effective price, fixed fees and seasonal peaks. Then record the fuels currently used for space heating, water heating and driving. A solar proposal, battery proposal, EV estimate and heat-pump estimate should all start from the same household baseline.
Do not stack savings estimates that each assume they are reducing the same kilowatt-hour. Model the sequence of changes and update annual consumption when a new EV, heat pump or heat-pump water heater adds electric load.
Match value to timing
Solar production value depends on location, shade, orientation, system losses and utility compensation. Battery value depends on charge source, usable capacity, efficiency, rate timing, outage goals and program rules. EV charging cost depends on vehicle efficiency, charging losses, mileage and the applicable rate period.
Use NREL or utility tools for production and interval data for load timing. A simple payback is an orientation, not a guarantee; financing cost, degradation, maintenance, replacement and resale assumptions belong in a lifecycle view.
Keep incentives outside the base case
Show project economics before incentives, then add only programs verified for the address, taxpayer, equipment, installer and installation date. Federal, state and utility rules can change, funding can close and a tax credit is not the same as a cash rebate.
Run low, central and high cases for future electricity prices and actual usage. State averages can frame a range, but they are not an individual tariff. Preserve each source date so the comparison can be refreshed before contract signature.
Sources and further reading
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