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A solar system’s size in kilowatts (kW) tells you how much power the panels make in full sun. It does not tell you how much electricity you get. The number that matters for your bill is kWh per day. As a rule of thumb, every 1 kW of panels makes about 4 kWh a day at 5 peak sun hours, the US average. The same 1 kW makes about 2.3 kWh a day in the UK, 3.0 in Canada, 2.6 in Germany and 4.8 in Australia. So a 5 kW system makes about 20 kWh a day in the US, or roughly 608 kWh a month.
This guide turns those numbers into real appliances for every common size from 1 kW to 20 kW. The calculator lets you pick your size and country, then edit the appliance list to match your home.
What will my solar system run?
Estimates use the formulas explained in this guide. Plan a complete system with the all-in-one calculator →
How to work out what a system makes
kWh per day = System size (kW) × Peak sun hours × 0.8
- Peak sun hours is the number of hours of full-strength sunshine your location gets per day, averaged over the year. The US averages about 5, Australia about 6, Canada about 3.8, Germany about 3.3 and the UK about 2.9. Our peak sun hours guide explains the idea, and solar by country lists more locations.
- 0.8 covers real-world losses: hot panels, dirt, wiring and the inverter. A 5 kW system at noon usually delivers about 4 kW, not 5.
Example: a 5 kW system in Denver, with 5.6 peak sun hours, makes 5 × 5.6 × 0.8 = 22.4 kWh a day, about 681 kWh a month.
kWh per day by system size and country
These are yearly averages using country-level sun hours. Cities vary, so use the calculator for your own figure.
| System size | US (5.0) | UK (2.9) | Canada (3.8) | Australia (6.0) | Germany (3.3) |
|---|---|---|---|---|---|
| 1 kW | 4.0 | 2.3 | 3.0 | 4.8 | 2.6 |
| 2 kW | 8.0 | 4.6 | 6.1 | 9.6 | 5.3 |
| 3 kW | 12.0 | 7.0 | 9.1 | 14.4 | 7.9 |
| 5 kW | 20.0 | 11.6 | 15.2 | 24.0 | 13.2 |
| 7 kW | 28.0 | 16.2 | 21.3 | 33.6 | 18.5 |
| 10 kW | 40.0 | 23.2 | 30.4 | 48.0 | 26.4 |
| 15 kW | 60.0 | 34.8 | 45.6 | 72.0 | 39.6 |
| 20 kW | 80.0 | 46.4 | 60.8 | 96.0 | 52.8 |
And per year, which is how your utility bill and any export payments add up:
| System size | US | UK | Canada | Australia | Germany |
|---|---|---|---|---|---|
| 3 kW | 4,380 | 2,540 | 3,329 | 5,256 | 2,891 |
| 5 kW | 7,300 | 4,234 | 5,548 | 8,760 | 4,818 |
| 7 kW | 10,220 | 5,928 | 7,767 | 12,264 | 6,745 |
| 10 kW | 14,600 | 8,468 | 11,096 | 17,520 | 9,636 |
Winter is the catch. In the darkest month a 5 kW system averages about 10.0 kWh a day in the US, 16.8 in Australia, 4.4 in Canada, 3.6 in Germany and just 3.2 in the UK. If you plan to go off-grid, size for winter, not the yearly average.
What each size can run in a day
These are realistic home mixes that fit inside each size’s daily output at 5 peak sun hours, with an inverter the same size as the panels. They are the same mixes the calculator shows.
| System | What it can run every day | kWh used of kWh made |
|---|---|---|
| 1 kW | 8 LED bulbs, a refrigerator, Wi-Fi, a TV, a laptop and a ceiling fan | 3.15 of 4.0 |
| 2 kW | The 1 kW list plus a microwave, a washing machine load and an hour of electric clothes dryer | 6.25 of 8.0 |
| 3 kW | 11 LED bulbs, fridge, Wi-Fi, 2 TVs, laptop, microwave, washer, dishwasher, 2 ceiling fans and 2 hours of an electric water heater | 11.91 of 12.0 |
| 5 kW | 14 LED bulbs, fridge, Wi-Fi, 2 TVs, 2 laptops, microwave, washer, dishwasher, 3 fans, a dryer load and EV charging for about 30 miles (50 km) a day | 18.00 of 20.0 |
| 7 kW | A full home with a chest freezer, desktop PC, 4 fans, a dryer load, a 12,000 BTU mini-split for 4 hours and a 3-ton central AC for 6 hours | 27.46 of 28.0 |
| 10 kW | A full home with 3 TVs, 5 fans, a 3-ton central AC for 6 hours, an electric water heater and daily EV charging | 39.18 of 40.0 |
| 15 kW | The 10 kW home plus a dryer, three mini-splits for 8 hours and a fourth for 4 hours | 59.40 of 60.0 |
| 20 kW | The 15 kW home plus a 1.5 HP pool pump for 6 hours and more mini-split hours | 68.47 of 80.0 |
The model assumes a 150 W fridge whose compressor runs about 35% of the time (1.26 kWh a day), a 3,300 W central AC running 6 hours at 70% (13.86 kWh), and a 7 kW EV charger running 1.3 hours (9.1 kWh, about 30 miles or 50 km of driving).
In the UK the same 5 kW system makes about 11.6 kWh a day. That still runs the 5 kW list without the EV, plus a mini-split for 4 hours, for 11.32 kWh in total.
“All day” and “at the same time” are two different limits
There are two limits, and people often mix them up.
- Energy (kWh per day). This decides how many appliances you can run for their normal hours. A 1 kW system makes about 4 kWh a day at 5 sun hours. That is enough for 3 refrigerators or 8 ceiling fans running all day, if nothing else is on.
- Power (watts at one moment). This decides what can run at the same time. At noon a 1 kW system delivers about 800 W. That powers 5 refrigerators or 13 ceiling fans at once, but only for the few hours the sun is strong.
The kettle shows the difference clearly. A 1 kW system makes enough energy for about 10 kettle boils a day (0.4 kWh each), but it cannot power even one 2,000 W kettle from the panels alone. You need the grid or a battery and inverter to supply the peak.
Typical household use and the size that covers it
These averages are approximate. Your own bill is the best guide.
| Country | Typical use | Size that covers it over a year |
|---|---|---|
| United States | about 29 kWh/day (10,500 kWh/yr) | about 7.2 kW |
| United Kingdom | about 8 kWh/day (2,700–3,000 kWh/yr) | about 3.2–3.5 kW |
| Canada | about 25–30 kWh/day | about 8.2–9.9 kW |
| Australia | about 15–18 kWh/day | about 3.1–3.75 kW |
| Germany | about 9–11 kWh/day (3,500–4,000 kWh/yr) | about 3.6–4.1 kW |
“Covers it over a year” means the system makes as many kWh as you use in a year. It does not mean you never buy power. You still draw from the grid at night and in winter, and export the surplus on sunny days. In practice, Australian installers fit 6.6 kW of panels on a 5 kW inverter as standard, because panels are cheap and the extra output covers mornings, evenings and cloudy days.
Worked example: a typical home in Atlanta
Atlanta gets about 5.0 peak sun hours. A home using the US average of 29 kWh a day needs 29 ÷ (5.0 × 0.8) = 7.25 kW to match it.
- A 7 kW system makes 28.0 kWh a day, 851 kWh a month and 10,220 kWh a year, about 97% of 10,500 kWh.
- That is about 17 × 420 W panels and roughly 38.5 m² (414 sq ft) of roof.
- At an assumed $3.00 per watt installed, 7 kW costs about $21,000. The 30% federal tax credit (Section 25D) no longer applies to systems a homeowner buys and installs after December 31, 2025. Leases and PPAs may still carry a business credit for a limited time.
For a more detailed walk-through see how many solar panels do I need and solar panels for 1,000 kWh per month.
Batteries and power outages
Panels alone stop working in a grid outage unless you have a battery and a backup-capable inverter. Count about 85% of a battery’s rated capacity as usable.
| Battery | Usable | Essentials only (about 0.3 kW) | Normal evening load (1 kW) |
|---|---|---|---|
| 5 kWh | 4.25 kWh | about 14.6 hours | about 4.2 hours |
| 10 kWh | 8.5 kWh | about 29.2 hours | about 8.5 hours |
| 13.5 kWh | 11.5 kWh | about 39.4 hours | about 11.5 hours |
“Essentials” here means a fridge and chest freezer (averaged over their on-off cycles), Wi-Fi, 5 LED bulbs, a TV and a laptop, which adds up to about 292 W. A central AC drawing 3.3 kW would drain the same 13.5 kWh battery in about 3.5 hours. See home battery backup size and is one Powerwall enough.
Air conditioning and heating
- Central AC, 3-ton: about 13.86 kWh a day for 6 hours of cooling. That alone needs about 3.5 kW of solar at US-average sun. See air conditioner wattage.
- Mini-split, 12,000 BTU: about 4.84 kWh for 8 hours, so about 1.2 kW of solar. Our mini-split on solar guide has the detail.
- Heat pump heating, 3-ton: about 12 kWh a day for 8 hours. Heating is needed most when solar makes least. In Germany a 10 kW system averages only 7.2 kWh a day in the darkest month, so the grid or a battery does most winter heating.
Incentives at a glance (October 2026)
- US: the 30% residential credit ended for systems installed after December 31, 2025. Check state and utility programs and net metering rules. See solar panels in the USA.
- UK: 0% VAT on home solar and batteries until 31 March 2027. The Smart Export Guarantee pays for exported kWh, often around 4p to 16p. See solar panels in the UK.
- Canada: the federal Greener Homes grant and loan have closed. Provincial rebates vary and most provinces offer net metering. See solar panels in Canada.
- Australia: the STC rebate reduces upfront cost (the scheme ends in 2030), and the Cheaper Home Batteries Program has run since 1 July 2025, with reduced support from 1 May 2026. See solar panels in Australia.
- Germany: 0% VAT on home PV up to 30 kWp, and a feed-in tariff of about 7.7 ct/kWh for small systems with partial feed-in from August 2026. See solar panels in Germany.
How to choose your size
- Find your yearly kWh on your utility bill and divide by 365.
- Divide that by (your peak sun hours × 0.8). That is the kW you need to match your use.
- Add room for an EV or heat pump you plan to buy. An EV doing 30 miles a day adds about 9.1 kWh a day.
- Check roof space: about 2.2 m² (24 sq ft) per 400 W panel, including gaps.
- Decide whether you want a battery for evenings and outages.
Detailed guides for each size: 1 kW, 3 kW, 5 kW and 10 kW.
FAQ
How many kWh does a 5 kW solar system make per day?
About 20 kWh a day at 5 peak sun hours, the US average. Expect about 24 kWh in Australia, 15.2 in Canada, 13.2 in Germany and 11.6 in the UK.
What size solar system does an average home need?
About 7.2 kW for an average US home using 10,500 kWh a year. A typical UK home needs about 3.2 to 3.5 kW, a German home about 3.6 to 4.1 kW, an Australian home about 3.1 to 3.75 kW and a Canadian home about 8.2 to 9.9 kW.
Can solar panels run my house during a power outage?
Only with a battery and a backup-capable inverter. Standard grid-tied systems shut down when the grid fails, for line-worker safety.
Does a bigger inverter make more kWh?
No. Panels make the energy. The inverter only limits how much power you can use or export at one moment.
Related guides
- What Size Solar System Do I Need for 30 kWh Per Day?
- How Much Power Does a Solar Panel Produce Per Day?
- How Much Power Does a 400W Solar Panel Produce Per Day?
- What Can a 100W Solar Panel Run? (Real Daily Numbers)
Sources and further reading
- NREL PVWatts Calculator: solar output estimate for any address.
- U.S. EIA: How Much Electricity Does an American Home Use?: average household use, about 10,800 kWh a year.
- ENERGY STAR: efficiency ratings and energy use of certified appliances.
- European Commission JRC: PVGIS: free solar output and optimum-tilt tool for Europe and most of the world.