How Many Solar Panels to Charge an EV? — US Calculator

The sizing question is small: how much energy your driving needs per day, divided by how much energy one panel makes per day. The first half this calculator can do from your mileage. The second half is a per-location figure.

So the per-panel yield field starts EMPTY. Run PVWatts for your address, take the daily kWh and divide by the number of panels modelled, and the panel count appears. Our whole-house panel-count guide covers the same arithmetic for the rest of the house.

Every field below is editable, and every default carries its source and date on the field itself — the defaults are a starting point, not a claim about your bill. We sell no hardware and take no installer commission; see how we verify.

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 ($/kWh)There is no national US export rate, so there is nothing to default to. Compensation is set state by state and increasingly utility by utility: some states still credit an exported unit at the full retail rate (true net metering), others pay an export rate well below retail (California’s NEM 3.0 is the largest example), and a few offer no compensation at all. A single national number would be wrong in most of the country. Look your state up on DSIRE, then type the rate your own utility actually pays.
  • Units per month per installed kWNo figure is printed here for two reasons. NREL publishes the authoritative per-location tool — PVWatts, at pvwatts.nrel.gov — but every NREL host was unreachable from our research session on 9 August 2026, and we do not publish numbers we could not read. It is also the wrong shape for a national default: output per installed kW varies by about half again between the cloudiest and the sunniest states, so a US average would misdescribe most roofs. Run PVWatts for your own address, divide the annual kWh by 12 and by the system kW, and type it in.
  • Battery cost ($ 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 dayFollows 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.

No result yet — the daily yield of one panel has no published figure for this market, so there is nothing to calculate from until you type your own. That is deliberate: a number we invented would look exactly like a number we verified.

How this calculator works — the actual arithmetic

  1. Daily energy = miles per day ÷ 100 × kWh per 100 miles, using 21 for a car and 4 for an e-bike or scooter.
  2. Panels = daily energy ÷ the daily kWh one panel produces, rounded up, minimum one.
  3. That second figure ships blank. It is the per-location number again: a panel’s daily output depends on where it is and how it faces, so PVWatts answers it for your address and we do not average it.
  4. Cost only appears if you supply a per-panel price. US residential solar is sold as an installed system, not as panels, so there is no national retail price for one module.

Why there is no worked example on this page

No worked example, because both inputs that would drive it — the daily kWh one panel produces and the price of one panel — have no publishable US default. The first is per-location and NREL answers it per address; the second does not exist as a national figure, because this market sells installed systems rather than modules.

For scale while you get a PVWatts figure: the average American drives about 37 miles a day, which at 21 kWh per 100 miles is roughly 7.8 kWh — the daily output of about eight modern panels in a sunny state.

Sources for this market’s defaults

What this calculator does not know

  • The per-panel yield is yours to supply and drives the entire answer.
  • Panel counts assume the roof has room and the orientation PVWatts modelled. Shading is not in this sum.
  • Charging losses between the meter and the battery are not modelled.
  • No panel price is printed, so the cost line stays hidden unless you supply one.

Frequently asked

How many solar panels does it take to charge an electric car?

For the average American driving about 37 miles a day in a car using 21 kWh per 100 miles, that is roughly 7.8 kWh a day — around eight modern panels in a sunny state and more in a cloudy one. The spread is exactly why this calculator asks for your own per-panel figure instead of printing one.

Can I charge my EV directly from solar panels?

In practice you charge from your home’s electrical panel, which the solar feeds. The array offsets the kWh your charger draws over the billing period rather than powering the car directly, which is why the sizing question is about energy per day and not about matching the charger’s kW.

Why does this calculator not show a panel price?

Because US residential solar is quoted as an installed system — labour, inverters, permitting and margin included — and no verified national retail price exists for a single module. Quoting a distributor listing would misstate what an American buyer actually pays. Use the installed cost per kW on the sizing calculator instead.

Is it worth adding panels just for the car?

Usually yes if you have roof space, because the alternative is buying those kWh at retail every month for the life of the car. Whether the exported surplus is worth anything on the days you do not drive depends on your state’s net metering rules, which vary enormously.

Guides that explain the numbers

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