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A 3 kW solar system makes about 12.0 kWh a day at 5 peak sun hours, the US average. That is about 365 kWh a month and 4,380 kWh a year. In the UK it makes about 7.0 kWh a day (2,540 kWh a year), in Germany 7.9, in Canada 9.1 and in Australia 14.4. At US-average sun it runs lights, a fridge, Wi-Fi, two TVs, a laptop, a microwave, a washer, a dishwasher, two ceiling fans and two hours of an electric water heater, using 11.91 kWh.
3 kW is a full home system in the UK and Germany, where households use far less electricity than in North America. In the US and Canada it covers less than half of a typical home. Here are the numbers.
What will my solar system run?
Estimates use the formulas explained in this guide. Plan a complete system with the all-in-one calculator →
What a 3 kW system includes
- Panels: 7 × 430 W (3.01 kW) or 8 × 400 W (3.2 kW).
- Roof space: about 16.5 m² (178 sq ft), including gaps between panels.
- Inverter: a 3 kW string inverter, or one micro-inverter per panel. A hybrid inverter adds a battery now or later.
- Battery (optional): 5 to 10 kWh is the usual match for 3 kW.
- Export: the surplus goes to the grid under net metering, the UK Smart Export Guarantee or a German feed-in tariff.
kWh per day by country
kWh per day = 3 kW × Peak sun hours × 0.8
| Country | Peak sun hours | kWh per day | kWh per month | kWh per year | Darkest month (per day) |
|---|---|---|---|---|---|
| United States | 5.0 | 12.0 | 365 | 4,380 | 6.0 |
| United Kingdom | 2.9 | 7.0 | 212 | 2,540 | 1.9 |
| Canada | 3.8 | 9.1 | 277 | 3,329 | 2.6 |
| Australia | 6.0 | 14.4 | 438 | 5,256 | 10.1 |
| Germany | 3.3 | 7.9 | 241 | 2,891 | 2.2 |
City differences are large. In Edinburgh (2.5 sun hours) 3 kW makes about 6.0 kWh a day. In Sydney (4.9) it makes about 11.8. See peak sun hours and solar by country.
What 3 kW runs every day
At 5 peak sun hours the system makes 12.0 kWh. A realistic mix:
| Appliance | Quantity | Hours/day | kWh/day |
|---|---|---|---|
| LED bulbs (10 W) | 11 | 5 | 0.55 |
| Refrigerator (150 W) | 1 | 24 | 1.26 |
| Wi-Fi router (12 W) | 1 | 24 | 0.29 |
| TV 43–55″ (90 W) | 2 | 4 | 0.72 |
| Laptop (60 W) | 1 | 6 | 0.36 |
| Microwave (1,200 W) | 1 | 0.25 | 0.30 |
| Washing machine (500 W) | 1 | 1 | 0.35 |
| Dishwasher (1,200 W) | 1 | 1 | 0.72 |
| Ceiling fans (60 W) | 2 | 8 | 0.96 |
| Electric water heater (4,000 W) | 1 | 2 | 6.40 |
| Total | 11.91 of 12.0 |
The water heater uses more than half the output. Swap it for a 500 W heat pump water heater running 4 hours at 80% and the same hot water job takes about 1.6 kWh, freeing nearly 5 kWh a day.
UK and German homes: at 2.9 sun hours a 3 kW system makes about 6.96 kWh a day. Drop the electric water heater and the rest of the list (lights, fridge, Wi-Fi, 2 TVs, laptop, microwave, washer, dishwasher, 2 fans) uses 5.51 kWh, which fits with room to spare on an average day.
One appliance on its own
How many of one appliance 3 kW can power at 5 sun hours. “At once” uses the about 2,400 W the panels give at noon.
| Appliance | Hours/day | How many, all day | How many at once |
|---|---|---|---|
| LED bulbs (10 W) | 5 | 240 | 240 |
| Refrigerator (150 W) | 24 | 9 | 16 |
| Chest freezer (90 W) | 24 | 18 | 26 |
| TV (90 W) | 4 | 33 | 26 |
| Desktop PC + monitor (200 W) | 5 | 12 | 12 |
| Ceiling fan (60 W) | 8 | 25 | 40 |
| Dishwasher (1,200 W) | 1 | 16 | 2 |
| Electric clothes dryer (3,000 W) | 1 | 5 | 0 |
| Electric oven (2,400 W) | 1 | 10 | 1 |
| Electric kettle (2,000 W) | 0.2 | 30 | 1 |
| Mini-split 12,000 BTU (1,100 W) | 8 | 2 | 2 |
| Central AC 3-ton (3,300 W) | 6 | 0 | 0 |
| Heat pump heating (3,000 W) | 8 | 1 | 1 |
| Heat pump water heater (500 W) | 4 | 7 | 4 |
| EV charging (7 kW) | 1.3 | 1 | 0 |
| Pool pump 1.5 HP (1,100 W) | 6 | 1 | 2 |
Can 3 kW run air conditioning?
A 12,000 BTU mini-split uses about 4.84 kWh over 8 hours, so 3 kW can run two mini-splits through a sunny day, or one alongside normal household loads. A 3-ton central AC uses about 13.86 kWh over 6 hours and draws 3,300 W, more than the 2,400 W the panels deliver at noon. 3 kW cannot carry it alone. See mini-split on solar and air conditioner wattage.
Battery backup for evenings and outages
An essentials load of a fridge and chest freezer (averaged over their cycles), Wi-Fi, 5 LED bulbs, a TV and a laptop draws about 292 W. Count 85% of a battery as usable.
| Battery | Usable energy | Essentials (about 0.3 kW) | 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 |
A 3 kW array makes 12 kWh on an average US day, enough to run daytime loads and refill a 5 kWh battery. In a UK winter, at about 1.9 kWh a day, it cannot refill even a small battery, so many UK owners charge the battery from a cheap overnight tariff in winter. See home battery backup size.
Worked example: a 3 kW system in London
London gets about 2.9 peak sun hours.
- Daily: 3 × 2.9 × 0.8 = 6.96 kWh.
- Yearly: about 2,540 kWh, or 85% to 94% of a typical UK home’s 2,700 to 3,000 kWh.
- Panels: 7 × 430 W on about 16.5 m² of roof.
The catch is timing. Most of that energy arrives between late morning and mid-afternoon, from April to September. Without a battery, a lot of it is exported. The Smart Export Guarantee pays for exports, often around 4p to 16p per kWh depending on your tariff. A battery lets you use more of your own power in the evening. Home solar and batteries are sold at 0% VAT until 31 March 2027. As a guide, a 4 kW system is often quoted at an assumed £5,000 to £7,000 installed. See solar panels in the UK.
Is 3 kW right for you?
| Country | Typical home use per day | 3 kW makes | Share covered |
|---|---|---|---|
| United States | about 29 kWh | 12.0 kWh | about 41% |
| United Kingdom | about 8 kWh | 7.0 kWh | about 87% |
| Canada | about 25–30 kWh | 9.1 kWh | about 30–36% |
| Australia | about 15–18 kWh | 14.4 kWh | about 80–96% |
| Germany | about 9–11 kWh | 7.9 kWh | about 72–88% |
- Good fit: UK and German homes, small Australian households, and US or Canadian homes with a small roof that want to cut the bill rather than clear it.
- Too small: homes with central AC, an EV or electric heating. Look at 5 kW or 10 kW.
- Germany: at an assumed €1,500 per kWp, 3 kWp costs about €4,500, with 0% VAT on home PV. Many German homes go to 4 to 6 kWp to cover a heat pump or EV later. See solar panels in Germany.
Common mistakes with 3 kW systems
- Matching the yearly total and expecting a zero bill. You still buy power at night and in winter unless you have a battery and enough surplus.
- Running big loads in the evening. Run the dishwasher, washer and water heater around midday to use your own solar.
- Ignoring roof direction. South-facing (north-facing in Australia) roofs give the most. East-west roofs make a little less but spread output across the day.
- Leaving no room to grow. If an EV or heat pump is likely, ask for an inverter and roof layout that allow more panels later.
FAQ
How many kWh does a 3 kW solar system make per day?
About 12 kWh a day at 5 peak sun hours, the US average. Expect about 14.4 kWh in Australia, 9.1 in Canada, 7.9 in Germany and 7.0 in the UK.
Can a 3 kW solar system run a house?
In the UK and Germany it can cover most of a typical home’s yearly use. In the US and Canada it covers about a third to two-fifths. It never runs a house at night without a battery.
Can 3 kW of solar run an air conditioner?
It can run one or two 12,000 BTU mini-splits on a sunny day. It cannot carry a 3-ton central AC on its own.
How many panels are in a 3 kW system?
About 7 × 430 W or 8 × 400 W panels, needing about 16.5 m² (178 sq ft) of roof.
Related guides
- What Can a 1kW Solar System Run? kWh per Day for Cabins, RVs, Sheds and Backup
- What Can a 1kW to 20kW Solar System Run? kWh per Day and Appliance List
- Solar Panels Australia 2026: Output by City, Battery Rebate, Feed-in Tariffs and Payback
- Solar Panels in the USA (2026): Cost, Output by City and Incentives After the Tax Credit
Sources and further reading
- NREL PVWatts Calculator: solar output estimate for any address.
- European Commission JRC: PVGIS: free solar output and optimum-tilt tool for Europe and most of the world.
- 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.