Loads of on-shore wind is likewise not metered. If you own a hill top farm, especially if you have industrial electricity loads (e.g. milking cows, lighting barns full of hens) it makes loads of sense to buy a modest turbine and install it on a suitable rise, it won't pay for itself over night but it's very competitive with other farm investments and not correlated. If electricity prices go up the turbine is better value, regardless of whether people are paying higher farm gate prices or your yields increased.

I think the estimate is that maybe as much as 5GW of UK wind nameplate capacity is unmetered, so it's a minority of wind power, but it's a big minority.

That seems very large - I can’t imagine plain farm owners could reach that kind of wind capacity, are you sure that’s accurate?

No, I'm not sure it's accurate because it's guessed by looking at suppressed demand.

There's no central register of unmetered power generation, the assumption used is that if on a windy day mysteriously we're buying 25GW from the grid across the country, while on a similar but calm day it was 30GW that suggests 5GW of electricity is not being purchased when it's windy, implying 5GW of unmetered electricity supply from wind.

And there are presumably other embedded systems making up some of that 5GW estimate. Farms just seem obvious because 1) I've seen farms with wind turbines 2) They're industrial scale electricity users, often occupying terrain very suitable for a wind turbine

Don't most domestic panels actually feed into the grid (so presumably would show up on the stats as solar generation)? Unless you've got a battery system at home.

Domestic panels are what we call embedded generation - they are connected to the distribution networks, not the main transmission network. The System Operator (NGESO) doesn’t have real-time insight into the distribution networks themselves - they are just visible as a net demand on the system. Embedded generation serves to reduce this demand by feeding power locally to the distribution network.

We can forecast the embedded generation in real-time, but it’s only post event once the meter data has been accounted for that we know what actually happened.

Interesting, thanks! Does that also mean power fed-in by domestic panels will only be used locally?

Export tariffs are so low (around 4p per kWh) compared with import tariffs (more like 35p per kWh last time I looked) that if you got solar panels recently, after the feed in tariff was stopped, then getting a battery too made sense. I imagine most new installations include batteries. We only really export in the summer or if we are away - we use virtually all the electricity we generate most of the year.

Depends on how it is setup and it varies in different areas, almost all are grid connected but many only "suck the excess power needed" from the grid when the panels can't produce enough, and only some of those "feed back" power when they produce too much.

They do - but as the rate you are paid for electricity is now a fraction of the price you are charged, most people without a battery try and align their energy use with production.

( The suns out! Put on the washing machine/dish washer etc ).

Not if you locked in a feed in tariff from years ago. They lasted 15 years I think.

Sure - don't know what proportion of solar panel installations that is though - it was an early adopter incentive.

Bottom line - not all the local solar production is measured at the grid level - much of it results in demand reduction which can't be directly attributed.

I think this will only increase - either due to local batteries, or more electricity driven heating systems ( heat pumps for example ).

And this isn't just homes - if you have a farm and have a big water reservoir which you fill by pumping water - and you had some solar panels - you'd just run the pumps when it was sunny - there is no particular need to run them at particular times ( same if you had a wind driven pump ).