Last reviewed: 4 September 2026. Appliance figures are typical
UK ratings; check the plate on your own appliance, because models vary widely.
Eight hundred watts is the legal ceiling for a plug-in kit’s inverter, and it is less than a
kettle. That single comparison tells you most of what you need to know: this is not a system that runs
your house. It is a system that quietly cancels out your background load, and understanding which
appliances it can and cannot cover is what separates a kit that pays for itself from one that
disappoints.
What 800 W looks like in appliances
And remember 800 W is the peak, reached on a clear day around midday with well-angled
panels. On a grey December afternoon you might be making 60 W.
| Appliance | Typical draw | Can 800 W cover it? |
|---|---|---|
| Broadband router | 10 W | Yes, easily, all day |
| Fridge-freezer (running) | 100–200 W | Yes |
| Laptop and monitor | 60–120 W | Yes |
| LED lighting, whole house | 50–100 W | Yes |
| Television | 60–120 W | Yes |
| Gas boiler pump and controls | 50–150 W | Yes |
| Washing machine (wash cycle, cold fill) | 150–500 W | Usually, except the heating phase |
| Dishwasher (heating phase) | 1,800–2,200 W | No, but it offsets part |
| Microwave | 800–1,200 W | Borderline to no |
| Kettle | 2,500–3,000 W | No |
| Electric oven | 2,000–2,500 W | No |
| Immersion heater | 3,000 W | No |
| Electric shower | 8,500–10,500 W | No |
| EV charger (7 kW) | 7,000 W | No |
The idea that makes it click: baseload
Stop thinking about running individual appliances. Every home has a baseload: the
continuous draw of the fridge, the router, the standby devices, the boiler controls, the things that
never switch off. In a typical UK home that is somewhere between 100 W and 300 W, around the clock.
A plug-in kit’s real job is to cover that baseload during daylight. It is unglamorous and it is
exactly where the money is, because baseload is the electricity you were always going to buy.
There is a second reason this matters. A self-installed kit cannot be paid for exports, so anything
generated beyond what the house is using at that instant is given away for nothing. Covering baseload
means the output is consumed by definition. This is the whole argument in
how to use more of your own solar.
Partial offset counts, and people forget it
An appliance drawing more than 800 W is not “not covered”. Electricity does not work in whole
appliances. If your dishwasher pulls 2,000 W and the kit is making 700 W at that moment, you buy 1,300
W from the grid instead of 2,000 W. You saved 700 W for as long as it ran.
Which leads to the single most useful habit: run the big appliances at midday. A
dishwasher on a delay timer for one o’clock on a sunny day quietly harvests several hundred watts that
would otherwise have been exported for free.
A realistic day
| Time | Kit making | House using | What happens |
|---|---|---|---|
| 08:00 | 120 W | 250 W | All consumed; buy 130 W |
| 11:00 | 560 W | 200 W | 360 W exported for nothing |
| 13:00 (dishwasher on) | 780 W | 2,100 W | All consumed; buy 1,320 W |
| 16:00 | 310 W | 180 W | 130 W exported for nothing |
| 19:00 (cooking) | 0 W | 2,400 W | All from the grid |
Two lessons fall out of that table. The wasted hours are the quiet midday ones, not the busy
evening. And the evening peak, when the house uses most, is precisely when a plug-in kit contributes
nothing at all. That gap is the argument people use for a battery, though a battery cannot go inside a
plug-in kit — see can you add a battery.
What it will not do
- It will not power your home in a cut. Grid-tied microinverters shut down when
the supply goes, by design, so nobody is electrocuted working on the line. A plug-in kit is not
backup power. - It will not charge an electric car meaningfully. A 7 kW charger is roughly nine
times the kit’s peak. - It will not heat water or run electric heating. Those loads are measured in
kilowatts, not hundreds of watts. - It will not do much between November and February. See
plug-in solar in winter.
The honest summary
Eight hundred watts runs the boring half of your house during daylight: the fridge, the router, the
lights, the standby load, the laptop. It cannot boil a kettle. Put your own numbers into the
savings calculator and read
the honest maths before deciding whether that is
worth a few hundred pounds to you.