Your Slow Cooker? Yes. Your Air Fryer? Not Quite. What Plug-In Solar Actually Powers.

The question nobody's asking clearly enough

Plug-in solar has had a very good few months of press coverage. Record solar output across Britain. Ed Miliband announcing supermarket rollouts. Germany already having over a million balcony systems installed. The policy is coming, the kit is arriving, and the interest is real.

But hidden inside most of the coverage is a question that deserves a direct answer: what can one of these things actually power?

Because "saves you £70–£110 a year" is technically accurate. It's also a bit vague. £70 a year is roughly what it costs to run a fridge for twelve months. It's also the annual WiFi router bill. It's the electricity that disappears into your phone charger and laptop every day without you noticing.

So let's be specific.

What an 800W system can genuinely run

The UK is capping plug-in solar inverters at 800W. That's the maximum the regulations allow, matching Germany's existing standard. Two 400W panels, one microinverter, one plug. When conditions are good — clear sky, south-facing, between 10am and 2pm — you're getting close to that full 800W.

Here's what fits comfortably inside it:

Your fridge-freezer (~150W peak, ~50W average). This is the crown jewel. A fridge-freezer runs constantly, and its average consumption is around 40–60W with peaks around 150W when the compressor kicks in. An 800W solar system covers this all day without breaking a sweat. The savings accumulate 24 hours a day, seven days a week. Over a year, running a fridge on solar adds up to real money.

Your WiFi router (~15W). Always on, barely drawing anything, and the solar system barely notices it's there. Powering your WiFi router from solar is essentially free, every day.

Your laptop (~45–65W while charging). One of the most satisfying uses of plug-in solar — sitting at your kitchen table, working on a laptop, knowing the whole thing is running on sunlight coming through the window.

Your phone and tablet chargers (~20W combined). Trivial load for the solar system. Charge everything simultaneously during your solar window and you'll never think about topping up in the evening.

A slow cooker (~300W on high). This is the one I love most. Put dinner on at 10am, let it cook through your solar peak hours, come home to a meal that cost you approximately nothing in electricity. The slow cooker uses around 300W — well inside the 800W limit — and it runs for hours, which is exactly when your panels are at their best. This is plug-in solar doing exactly what it's supposed to do.

LED lighting (~10W per bulb). If your south-facing balcony catches the afternoon sun and you work from home, you could run the lights in the room you're working in on solar power. Not a huge saving, but satisfying.

At full output on a good day, your 800W system can comfortably cover all of the above simultaneously: fridge, router, laptop, phone charging, and a slow cooker with headroom to spare.

What it can't do alone

This is where the press coverage gets a bit optimistic if you're not paying attention.

Air fryer (~1,400W). The UK's favourite appliance of the last three years draws between 1,200W and 1,500W when running. That's 600W beyond what your plug-in solar can supply on its own. Your solar system will offset some of that load — it'll be contributing its 800W while the air fryer draws 1,400W, meaning 600W comes from the grid rather than 1,400W — but you're not running an air fryer on solar alone.

Plug-in air conditioning (~1,000W). Same story. Portable air conditioning units typically draw 900W to 1,200W. Above the limit. Solar offsets some of it; the grid covers the rest.

Kettle (~3,000W). A standard UK kettle draws between 2,200W and 3,100W. There's no world in which an 800W plug-in solar system runs a kettle. The solar is still helping — it's still offsetting electricity use elsewhere in the house — but the kettle itself is running on the grid.

Washing machine (~2,000W). Another one that exceeds the limit during the heating phase. Smart timing still matters (run it during your solar peak so the grid electricity you're drawing costs less at the margin), but plug-in solar isn't replacing your washing machine's draw.

The honest framing: offset, not replace

This is the frame that makes plug-in solar genuinely useful rather than disappointing.

Plug-in solar is an offset — it reduces what you draw from the grid by covering the loads it can handle. When your solar is outputting 800W and your fridge is using 50W, your router is using 15W, your laptop is using 60W, and your slow cooker is using 300W, that's 425W coming from sunshine rather than your electricity supplier. Every unit of that is electricity you're not paying 24–25p for.

The households that will save the most aren't necessarily those who try to run everything on solar. They're the ones who understand their solar window — know when it's generating, and run the right things at the right time.

That's the difference between a 3-year payback and a 5-year payback on a £400–£500 kit.

Europe's been doing this for years

The Euronews analysis that prompted this post is worth looking at for context. Solar energy saved Europe more than €100 million per day in March by displacing imported gas. The analysis projects savings of more than €67 billion for the continent in 2026 if gas prices stay elevated due to tensions around Iran.

Germany — where plug-in solar has been legal and mainstream for several years at prices as low as €200 — has over 1.5 million systems installed. German households figured out years ago that fridges, routers, and always-on appliances are where these systems earn their keep. UK households are about to learn the same thing.

The UK's regulatory framework is now in place (BS 7671 Amendment 4, live April 2026). Supermarket rollouts — Lidl and Iceland confirmed, others expected — are coming this summer. The kit is already available on Amazon now if you want to get ahead of it.

When is your 800W actually 800W?

Here's the piece that matters and doesn't get talked about enough.

Your plug-in solar system is only outputting close to 800W at its peak — clear skies, optimum angle, full midday sun. At 9am on an overcast February day, it might be outputting 50W. On a bright April afternoon between 11am and 2pm, it could be hitting 700W+ consistently.

The difference between a household that saves £110 a year and one that saves £70 is mostly about whether they know when those peak hours are happening and act on them.

That's what Sun Hours does. Enter your postcode and your system's best-ever single-day output, and you get a 7-day kWh forecast with an hourly generation chart showing exactly when your output is high enough to run each of the appliances above. When the chart shows you're at 700W output, that's the moment to put the slow cooker on. When it shows you're at 200W because cloud is rolling in, the kettle moment has passed anyway.

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