Plug in solar panels - announced

I can almost guarantee it wont

needs mains there to synch

The "widow-maker" plug would have 240V and 50Hxz sense, without external lecky the inverter of the mini PV would not operarte and cut out immediately on disconnect which electronically would be more of a challenge

In short:

- plugging into a mains socket is not a problem. The inverter shuts down within milliseconds when it detects the mains has gone away, which means it's safe to unplug when generating.

- when on a Type AC RCD/RCBO there's a risk of blinding the RCD by DC leakage currents, which means it wouldn't be sensitive to earth leakage faults on anything that shares the RCBO. I presume that tighter design means they can prevent such DC leakage. Better is to have it on a separate circuit with a Type A RCBO.

- fire safety when paired with a battery (ie don't stick it in the loft and burn your house down if the battery gets cooked). Sodium ion batteries are cheaper and much more robust and I hope this will make it easier - eg you can just plonk them outside and they're fine even if it's baking or freezing.

Yes.

There is an additional issue in terms of getting paid for export - you don't unless you have MCS approval which means getting an install from a firm who have paid the MCS tax, or paid £250 to Octopus. You also need to submit G98 to your DNO.

There's a further headache for the DNO in terms of having lots of generation connected to the local grid at times of low demand. It's possible there may be a requirement for the inverter to be internet-connected so the DNO can tell it to stop exporting if there is a surplus.

Theo

Who cares if it's battery can tode you over for a few hours.

Our base level consumption is c. 300W - using some smart plugs to turn off the fridge/freezer we could tick along for a while.

I am intrigued by these offerings as - so far - they aren't connected to a scam scheme.

How can it do that pray?

What happens if there's another of them elsewhere in the house? Will one detect the other as 'supply present'?

More to the point surely people will try and bypass the above shutdown in the hope of keeping, say, the freezer going if there's a power cut.

... and anyay, how on earth do you detect, **reliably**, if the circuit you're connected to is part of the national grid?

I did wonder if some enthusiastic DiYer would buy several of these PV panels plus microinverters.

Then stick some mounting rails on the roof,

put several sets of PV panels and install the several microinverters in the loft,

Wire up the micro inverters in parallel in order to get close to a full PV install,

and without paying the MCS fees or for a sparky to install and certify?

and then put in a a battery to balance demand and supply?

Yes most do, however if you wish to be paid for the exported power you need to have a seperate arrangement with a supplier.

These things (assuming we are talking reasonably quality product and not some tat from temu), have grid tied inverters. So unless connected the a socket that is already live, they will not enable their own output. If the mains fails, then they also shutdown to precent "islanding".

Now in theory that makes them safe ish - however there are a bunch of unknown and untested corner cases where you might get different results. Part of the issue is there are no formal standards or test regimes

For a single device on its own. they are designed to prevent that. However what would happen should you be running multiple units is one of the unknowns. Could they see outputs from each other such that they think the grid is still live?

same here - but likely less robust since they are not installed into a house with designed in controls for use of solar pv.

popular in Germany - so called "balcony solar"

might depend on the meter.

I am no electrician but I don't understand if it generates AC power and you plug it into another AC socket the 50hz phases of the one would have to match the other, because if they didn't - I don't know what would happen, BANG! maybe. But they must have thought of that.

Tim w

I realise this was a flippant drive by posting.

When I fully read the posted link it was comprehensive and answered most issues.

Mea culpa

Dave R

There are in Germany, eg VDE-AR-N 4105:

AIUI in the UK G98 would still apply, ie the microinverter still needs to have a G98 approval - this appears to be our take on the VDE standard.

Many UK microinverters already have G98, eg up to 1kW there are 364 approved models:

The requirements to support 'plug in' may be an additional testing regime on top of that, or may be covered in BS7671 18th edition Amendment 4 (section

Possibly, but I expect they do a lot of checks and if anything goes out of spec they disconnect. So it's likely they wouldn't be able to hold up a stable island for long before it collapses.

Theo

The reason the UK is so behind with this tech, is the greed of owners all wanting to "make money".

If folk were merely content with reducing their own bills by (wild guess)

I suppose you could convert any excess energy into bitcoins, thus bypassing the grid?

You jest, I believe. However there was a story a while back that some sun- drenched African countries could make a *lot* of money by solar powered coin "farming". At which point "proof of stake" was suddenly a thing, rather than proof of work.

If you match what the grid is doing, at the plug, then make your "hard" connection to the plug using a switch or relay, you expect zero power transfer, and no bang.

The grid frequency changes moment by moment, the voltage can change (in your house wiring), there are all sorts of things you could track while you maintain your zero power transfer condition.

You are not synchronous at this point, because if the grid makes one of its step changes in frequency (wander), your internal PLL is not at the same frequency. You track and gradually close in on the correct frequency again.

For the power grid, they record the number of cycles delivered on a given day, and they try to adjust that, so that on a day by day basis, naive electromechanical clocks maintain reasonably accurate time. They couldn't do that, if somebody did not count the cycles, and note the plus or minus deficiency, and correct for it. It does mean during the day, the electromechanical clock could be ahead or behind time. An attempt is made at least once a day, to bring it back to the correct count of cycles (so the average for the day was 50.00Hz).

I like this incident, because it teaches us about a relationship we didn't know was there. If countries share a grid, they all have to play nice, and not throw toys out of pram.

Paul

If you are connected to the grid, you are matching its frequency and phase, It's like a cyclist grabbing hold of a bus. You might be pushing it along or it might be dragging you, but you are both going the same speed. And the mains does not undergo 'step changes'. Like the bus there is a lot of inertia there...