Solar Calculator US — What Size System Does Your Home Actually Need?

6 fields on this page ship blank, on purpose

No source we can cite publishes these figures for US, so the fields start empty rather than pre-filled with something plausible. The calculator prints no result until you supply your own.

• What one exported unit is worth ($/kWh) — There is no national US export rate, so there is nothing to default to. Compensation is set state by state and increasingly utility by utility: some states still credit an exported unit at the full retail rate (true net metering), others pay an export rate well below retail (California’s NEM 3.0 is the largest example), and a few offer no compensation at all. A single national number would be wrong in most of the country. Look your state up on DSIRE, then type the rate your own utility actually pays.
• Units per month per installed kW — No figure is printed here for two reasons. NREL publishes the authoritative per-location tool — PVWatts, at pvwatts.nrel.gov — but every NREL host was unreachable from our research session on 9 August 2026, and we do not publish numbers we could not read. It is also the wrong shape for a national default: output per installed kW varies by about half again between the cloudiest and the sunniest states, so a US average would misdescribe most roofs. Run PVWatts for your own address, divide the annual kWh by 12 and by the system kW, and type it in.
• Battery cost ($ per kWh) — No US source we can cite publishes a residential battery product price per kWh. Berkeley Lab publishes paired PV+storage pricing per kW of PV capacity — a median $5.3/W cash against $3.5/W for stand-alone PV — which is a whole-system installed price, not a battery price, and roughly 90% of that paired sample is California. Dividing the one by the other would turn a Californian system premium into a national module price. Type the per-kWh figure from your own quote.
• Battery modules added to a new system ($ per kWh) — Blank for the same reason as the battery cost above: Berkeley Lab prices paired systems per kW of PV, not storage per kWh, and its paired-pricing sample is overwhelmingly Californian. For scale while you get a quote, its median residential battery in 2024 was 13.5 kWh at a 2-hour duration.
• Price of one panel ($) — US residential solar is sold as an installed system, not as panels — the per-watt prices published for this market are whole-system prices including labour, inverters, permitting and margin. There is no verified national retail price for a single module, and quoting a distributor or marketplace listing as one would misstate what an American buyer actually pays. Use the installed cost per kW above instead.
• Usable kWh per panel per day — Follows directly from the generation figure above, which we could not source because every NREL host was unreachable on 9 August 2026. Run PVWatts for your own address with your panel count, then divide the daily kWh by the number of panels.

• The generation figure is yours to supply, and it moves the answer more than anything else on the page.
• Berkeley Lab’s prices are 2024 installs in 2024 dollars, published October 2025 — a national median, not a quote, and state medians vary widely around it.
• Every cost here is gross. The federal tax credit and any state or utility incentive come off afterwards.
• Backup sizing assumes a flat load. A heat pump or an EV charger is not a flat load.