UK households free to install plug-in balcony solar panels from end of August

Point 1 isn’t true anymore as of this week. The first UL3700 inverter from Hoymiles just got approved and is being sold by Bright Saver for consumers https://www.brightsaver.org/balcony-solar-kits

I think point 2 will change once this becomes common. Once there is demand Home Depot etc are the perfect place to sell individual medium sized panels.

Hopefully it won't take 10 years for this to become easy.

If I understand the devices correctly, the current generation of microinverters should meet all power-limit requirements and disconnect if the grid goes away.

Hoymiles just got UL3700 approved this week and sold by Bright Savers

State plug in solar legislation tracker: https://www.brightsaver.org/legislation-tracker

(passed in 10 states, 2 awaiting signatures, as of this comment)

In Uk, If an old (rare) mechanical meter the meter will go backwards, the ideal. If a dumb digital meter the meter will simply pause counting up. If a smartmeter again the import reading will pause but a separate export reading will count up, for which you get no credit or debit but its nice to know. Ideally as battery prices drop you end up buying a battery that soaks up any surplus for later and so you don't lose any back to the grid. If you pay up for a commercially installed solar you can get paid for what you export but with plug in solar you just give it away.

It is likely not going "back to the grid" unless you have the rest of your house shut down; where the "balcony solar" output is greater than your house usage. These systems are "back-feeding" into your circuits, and if you have it on a circuit that is less heavily loaded than the panels are providing, the other branch circuits are going to sop up that usage before it literally feeds back into the grid.

You'd most likely need a different meter (and utility cooperation) to get credit for power supplied to the grid. These are expected to locally offset current use, so you pull less power through the meter, any surplus generation is a gift to the grid.

I believe that they're safe, but I don't understand how.

My circuit breaker is specced to be a bit lower than the capability of the downstream wiring. For the sake of argument let's say that the breaker is 16A and the circuit wiring is good for 20A.

Now the panel injects 8A into the circuit and suddenly I can pull 24A (16 from the circuit plus 8 from the panel), but that's through wiring that's only rated for 20A.

Does it rely on the fact that the actual amount of current from the panel is small (but continuous) and so we're likely to not push anything over the line?

How do these plug in panels prevent backfeeding in the case of a complete outage? IE: if lines are down and linemen go to work on lines with trees on them etc how can they be assured they're not energized?

Bills are popping up in state legislatures across the United States to legalize plug-in solar. I wrote about a bill that was up for consideration here in Washington state earlier this year: https://www.brethorsting.com/blog/2026/01/washington-should-...

Unfortunately, the bill didn't make it over the finish line during the 2026 session. The Washington legislature only met for two months this year: https://www.brethorsting.com/blog/2026/01/how-the-washington...

I'm in Seattle, where we enjoy some of the cheapest electricity costs in the country thanks to abundant hydroelectric generation and a public, city-owned utility, but back-to-back 10% rate hikes were just announced for 2027 and 2028, and I hope that spurs our state legislature to take balcony solar more seriously.

Depends on power output.

Has been legal in Germany for some years but inverters have to be limited to 800W output so it doesn't overload the circut. Additionally, you're limited to 4 panels max 2000w peak total.

A lot of companies also offer batteries where the panels directly plug into and then into the wall. That way you're only feeding into your household when you're using it.

If you set it up correctly a lot of households manage to save up to 35% in electricity.

> I’ve always heard it’s significantly risky to plug power-generation directly into a wall outlet.

Depends on what is generating the power.

Traditional fuel-powered emergency generators are indeed risky, as they are designed to operate on their own. They do not need the grid to be present as they will generate their own sine wave. This means they'll happily feed power outside your house, and nothing is preventing you from getting a giant "bang" when external power is turned on again. For this kind of generators you need a way to XOR the two, usually with a physical interlock turning off the main incoming fuse before the generator fuse can be engaged.

Most solar panels, including those plug-in ones, are designed to operate with a grid present. They don't generate a sine wave, they just sense the incoming wave and "push back". Turn off the external power and they'll stop operating. So no power during an outage, but also no risk of electrocution.

With plug-in sources there's an additional risk, namely that something else on the same fuse can draw power from both the outside grid and from the additional source. The breaker in your mains panel will still trip at (say) 15A, but there's now a second thing supplying current. If that provide an additional 15A, some piece of equipment on that circuit can now draw 30A without tripping any breakers - and its plugs and wiring are not designed for 30A, so they'll catch fire. This has to be avoided by giving the power source its own dedicated hard-wired breaker. Or, in the case of those plug-in PV panels: limit their power to something which is unlikely to cause issues in practice. That 15A wiring isn't going to melt at 16A.

The US is a patchwork, but it is legal in some places, including Utah!

https://grist.org/buildings/balcony-solar-is-taking-state-le...

More in other links on my page too: https://www.earth.org.uk/note-on-G83-lite.html#sources

The main risk factor is people trying to pump too much juice into a wall socket rated for a lesser current. Plus the connector needs to be male - shock risk. The combination of live and male is not generally something you see in households and people may not register that it’s something outside of normal household risk profile.

That plus bit of risk of things being energised that say a lineman thought would be out. This can be mitigated by using systems that only feed in when they sense it’s connected to the grid

U.K. wiring is obviously different

https://youtu.be/Na4LTD1M6nw

Seemed to cover a fair amount of the issues (or non issues)

https://www.brightsaver.org/legislation-tracker has a beautiful day visualization map that shows state by state status!

The broader North East / New England is very far along!

Is plug-in solar explicitly illegal in most states?

4 years is a pretty good payback time, it's a pretty obvious investment if you can afford it, and it's pretty affordable (with the added bonus that if you're renting, you can take it with you). Solar panels tend to last a pretty long time, really the only worry is whether the manufacturer has cheaped out on the electronics (cleaning is literally going to be wiping it with a sponge once a year or so).

(Insulating your house or getting double glazing, for example, takes a lot longer to pay itself back, and these are pretty popular home improvements despite that and the higher outlay)

I see it more as a way for relatively well off people to do a little bit for the environment rather than any sort of solution of high energy prices for the poor. The nice thing, of course, is that the more people buy them, the cheaper electricity is for everyone else, so you're doing everyone else a small favour by having one.

I'll certainly be buying one, not because of the ROI/payback calculation, but just because it's fun to talk about with my kids and a nice thing to do.

Similarly, plug in batteries are on the way (see recently Octopus announcement). I'll probably buy one for the same reasons.

That said, the payback time also looks very favourable, especially relative to a full rooftop install, so you don't even need to be alturistic!

I just put 2 460W panels and one of these 800W micro inverters on my shed. Total cost was just under £300 delivered, inc £15 of cabling. In the 5 weeks since it has been online (albeit in very good conditions - heat wave, summer but mounted flat on roof is suboptimal) it has generated 156kWh and saved £45 in electric costs.

Yeah I question the overall economics. I wonder if balcony solar is a net negative for the environment.

If you assume the cost of a thing can serve as a rough proxy for the energy inputs of the thing then until you meet RoI you're likely negative (environmentally speaking)

casual if the RoI for these is 4-8 years. and some stats[1] show most renters don't stay in one place that long. Given that the majority of people move at least once inside the RoI period, and may not move to somewhere with a balcony that can set up the solar it's possible that more of these system will end up in a landfill than actually help the environment.

which isn't to say I'm against deregulation here. I don't see any real reason to prevent people from being allowed to set them up so long as they're safe. and certainly some people will get great use out of them. but I also don't think they're as categorically great as they're made out to be.

[1] https://www.redfin.com/news/renters-staying-put-longer/

Panels have 25+ year lifetimes. Anything after the break even is free energy. There is no material maintenance cost.

You think a balcony solar panel is going to die after 4 years? Why? What makes it different from any other solar panel? They have lives in decades.

You're spouting tired anti-solar talking points. Again, why?

[dead]