UK households free to install plug-in balcony solar panels from end of August • Hacker News Board

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

#21

Post by varispeed » Thu, Jul 23, 2026, 5:14 PM UTC

So it costs £400 and can shave up to £100 a year - how it was calculated? In best case scenario you'll have to hang this thing off balcony for 4 years to break even. Will it be good after 4 years? I cannot see the economics of that. If it shaves £50, then it's 8 years.

How long do they last? How much maintenance costs (cleaning etc.)

Sounds like a way to stuff the poor with copium device. The rich will get minted and government doesn't have to resolve the problem of expensive electricity for another election cycle.

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

#22

Post by linsomniac » Thu, Jul 23, 2026, 5:16 PM UTC

dwroberts wrote: post #19

Not sure I quite get how this works from the wall plug PoV: if you have smart metering on your electricity, will it actually show you drawing less from the grid due to the input provided by the panels to your local wiring etc? Or is that it actually goes back to the grid and you would pay your bill minus the amount you’ve fed back in?

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.

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

#23

Post by crote » Thu, Jul 23, 2026, 5:17 PM UTC

mock-possum wrote: post #2

Huh! Where does this stand in the US? I’ve always heard it’s significantly risky to plug power-generation directly into a wall outlet (though you can do it in a pinch)

> 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.

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

#24

Post by toomuchtodo » Thu, Jul 23, 2026, 5:18 PM UTC

linsomniac wrote: post #20

As I understand it, the US is mostly waiting for UL listing of equipment, which hasn't been a priority because no US locals have allowed them. With Utah and others starting to allow them, UL listing will likely come at some point (hopefully shortly) thereafter. There's this device: https://usa.apsystems.com/ez1-installers/ And also this: https://connectder.com/

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

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

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

#25

Post by toast0 » Thu, Jul 23, 2026, 5:19 PM UTC

dwroberts wrote: post #19

Not sure I quite get how this works from the wall plug PoV: if you have smart metering on your electricity, will it actually show you drawing less from the grid due to the input provided by the panels to your local wiring etc? Or is that it actually goes back to the grid and you would pay your bill minus the amount you’ve fed back in?

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.

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

#26

Post by toomuchtodo » Thu, Jul 23, 2026, 5:20 PM UTC

varispeed wrote: post #21

So it costs £400 and can shave up to £100 a year - how it was calculated? In best case scenario you'll have to hang this thing off balcony for 4 years to break even. Will it be good after 4 years? I cannot see the economics of that. If it shaves £50, then it's 8 years. How long do they last? How much maintenance costs (cleaning etc.) Sounds like a way to stuff the poor with copium device. The rich will get minted and…

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

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

#27

Post by [deleted] » Thu, Jul 23, 2026, 5:21 PM UTC

toast0 wrote: post #25

dwroberts wrote: post #19

Not sure I quite get how this works from the wall plug PoV: if you have smart metering on your electricity, will it actually show you drawing less from the grid due to the input provided by the panels to your local wiring etc? Or is that it actually goes back to the grid and you would pay your bill minus the amount you’ve fed back in?

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.

[deleted]

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

#28

Post by bryanlarsen » Thu, Jul 23, 2026, 5:21 PM UTC

Havoc wrote: post #10

mock-possum wrote: post #2

Huh! Where does this stand in the US? I’ve always heard it’s significantly risky to plug power-generation directly into a wall outlet (though you can do it in a pinch)

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. T…

> This can be mitigated by using systems that only feed in when they sense it’s connected to the grid

Which are the only ones that are legal.

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

#29

Post by RobinL » Thu, Jul 23, 2026, 5:22 PM UTC

varispeed wrote: post #21

So it costs £400 and can shave up to £100 a year - how it was calculated? In best case scenario you'll have to hang this thing off balcony for 4 years to break even. Will it be good after 4 years? I cannot see the economics of that. If it shaves £50, then it's 8 years. How long do they last? How much maintenance costs (cleaning etc.) Sounds like a way to stuff the poor with copium device. The rich will get minted and…

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!

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

#30

Post by rcxdude » Thu, Jul 23, 2026, 5:29 PM UTC

varispeed wrote: post #21

So it costs £400 and can shave up to £100 a year - how it was calculated? In best case scenario you'll have to hang this thing off balcony for 4 years to break even. Will it be good after 4 years? I cannot see the economics of that. If it shaves £50, then it's 8 years. How long do they last? How much maintenance costs (cleaning etc.) Sounds like a way to stuff the poor with copium device. The rich will get minted and…

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)