Plug-In Solar Savings Calculator (feedback prototype)

Compare a kit

Your estimated savings

solar energy per year

What if electricity rates rise? Try 3% per year, about the US average increase over the past decade. This is a scenario, not a forecast.

Your average monthly electric bill ($, optional)

Add this to see about how much of your bill a kit could offset.

Your electricity rate ($ per kWh)

Your exact rate is on a recent power bill, usually in cents per kWh.

Your ZIP code (optional)

Average peak sun hours per day

From the same PVWatts typical-year model as the estimate. The prefilled value is a US starting point: one city per state plus DC, weighted by state population, at the tilt of the selected mounting. Enter a ZIP for your local value. Shown for reference - the hourly model always uses its own sun data.

Solar panels (watts)

Inverter output limit (watts AC)

The most power the kit can feed into your home at once. Some kits ship with a lower setting you can raise in the manufacturer's app.

Balcony or ground mount?

Ground assumes a sunny, unshaded 35-degree angle facing south; Balcony assumes vertical panels facing south.

Production factor (%)

Production-side losses only: equipment, wiring, temperature and sun angle at your location.

Share of solar your home uses (%)

The share of the solar power your home absorbs while it is being made. Any solar not used at home earns no savings or export credit in this estimate.

How we estimate this

Yearly solar energy comes from an hour-by-hour model: the PVWatts Version 8 engine (NREL's open solar model) simulates a typical year of real weather at your location with your panel watts, inverter limit, a 96% assumed inverter efficiency and no rear-side (bifacial) gain. With no ZIP, the same model is averaged across the largest city in every state plus DC, weighted by state population. Only if the modeling service is temporarily at its limit does the page say so and fall back to a simple daily estimate: peak sun hours x 365 x system size x production factor, capped at the inverter limit, labeled as not the hourly model. Savings count only the share your home uses: savings = used energy x your electricity rate. Any solar your home does not use earns no savings or export credit in this estimate. Ground mounting assumes a sunny, unshaded 35-degree tilt facing south; a balcony assumes vertical panels on a south-facing railing. The sun hours and production factor below come from the same model and are shown for reference, not editable inputs. Disclosure: this calculator was built by Teresa Russell, founder of OwnWatts, a plug-in solar shop. This is a feedback prototype - no products are sold or linked here.

Panel watts and inverter output are yours to edit: the hourly model applies the inverter limit hour by hour, so oversizing panels past the inverter clips the peak but keeps morning and evening production.
Mount sets the geometry the estimate assumes: Ground is a sunny, unshaded 35-degree tilt facing south; Balcony is vertical panels on a south-facing railing with no rear-side gain, since the back faces the railing.
If the modeling service is temporarily at its limit, the estimate falls back to the simple daily estimate, labeled below the results - never a misleading zero. Other failures show no estimate rather than switching formulas.