Tim H, does my DNO have to meet a time limit on approving Export ? last year they & Octopus were useless and took almost 5 months to approve what was an existing system, already registered and FiT approved (funny how the ok finally lands in Dec after we've lost all the summer potential !)
We're going to replace faulty batteries in the current system soon and apparently I need approval again as we're fitting larger capacity as the tech has moved on in the last few years
I don't believe so, there is considerable complexity involved when getting DNO approval for export. They have to automatically accept anything up to 3.6kW, but anything over and they get the right to approve it.
It's because the national grid was never designed (because it was completely impossible back in the '50s and'60s) to have small generators producing 240v providing power that could be transformed up to the high voltages used on the transmission network. As a result, any domestic export power has to be used up in the 240v distribution network that your house is connected to.
In urban areas, this isn't a problem as there are loads of premises connected and the power gets soaked up by everyone else. The DNO doesn't have to extract so much power from the transmission network and everyone's happy.
In more rural area, it gets a bit more problematic, especially where you get a few homes being supplied from a local high-voltage supply going to one of those little transformers sat up a telegraph pole. In these cases there often simply aren't enough premises connected to the transformer to reliably soak up excess export power. So there's no value to the power being produced as all it does is warm up the wires.
The big challenge for DNOs and suppliers is the system called the Balancing Mechanism. Every DNO and supplier has to tell the National Grid Company how much electricity they need for any given half hour in advance. If it turns out they need more or less electricity than this, they get hit with massive costs.
The main reason our electricity prices in the UK are so high is down to Thatcher's 'Dash for Gas' strategy. She didn't listen to the strategy folks at CEGB (because she wanted to privatise everything) and so now we depend far more than other countries in Europe on gas generation to fill in the gaps in supply. If the suppliers and DNOs get their estimates wrong and we have to spin up a couple of gas generators the cost per kWh is absolutely huge and skews our domestic prices up as it's the price of gas that dominates our wholesale market.
