Let’s look at Solar PV again

If you look back through the posts to 2011 and 2012 the solar PV system on the house was installed as the house was built. It is an “in-roof” system, rather than “on-roof”. Apart from anything else, it save tiles – or in this house’s case, slates. (I started to write this in August, btw.)

It has been a frustration for some time that, if there was a day time power cut, the solar PV turned off. The inverter could see the mains or lack of it, and shut down. Clearly, without some safety devices it has to, so that the linesmen repairing the fault don’t get electrocuted by the power that the system would continue to export to the grid. But I have considered that it should not be beyond the wit of an electrical engineer to create system that, in the event of mains failure, isolates the house from the mains and makes it impossible to re-connect until the power outage has been rectified. And, indeed you now can. Interesting video on the Fully Charged website showing the big “backup” box, which does just that – it switches over to the local battery instantaneously. And the solar PV continues to charge the battery/supply power to the house, provided that the sun is shining etc. But the key word here is battery.

To go back a bit. When the system was installed on this house, the Feed in Tariff (FiT) had just reduced from (very roughly) 40p/kWh generated to about 20p. Still worthwhile. Since then the FiT has been withdrawn – but the price of solar PV has much reduced. Whatever I write here will go out of date but, again very roughly, it’s now about £1 per watt peak installed. So a 4kWp system should cost roughly £4,000.

So where are we with batteries? When I last wrote about this, it was still far from being a sensible return on investment – I would not save enough (of the cost of) electricity to get my money back on the costs of a battery system – by a large margin. I don’t have that amount of spare cash to be able to indulge that level of “green altruism”! And, in my opinion, it still isn’t.

Step another bit forward – many of you will have seen articles about “V2G” which stands for Vehicle to Grid. If I had an electric vehicle (EV), then perhaps I could use its battery instead of buying one for the house separately – I’ve spent A Lot Of Money on an EV, why buy another far from inexpensive battery? Well, it’s coming, though not quite yet, I’m told.

I am in the throes of joining a trial called Powerloop, an experiment set up by Nissan, Octopus Energy, Octopus Electric Vehicles, UK Power Networks and two academic partners (can’t find their names at the moment). Essentially, provided I am in UKPN’s area, am prepared to lease a Nissan Leaf from Octopus EV, move to Octopus Energy (single tariff), am willing to connect the car 12 times a month to the special charger/discharger (Wallbox) between 6pm and 5am I will get paid £30/month. The Wallbox charger is supplied and fitted free and becomes mine at the end of the trial. See the Powerloop website, rather than my writing all the details here and possibly getting them wrong. You could join too. At the time of writing (October 2020) Octopus/Powerloop told me that there were still vacancies to join the trial. Oh yes, you have to own your own home and have off-road parking.

Checked out the car at a local dealer. Thought it might be a bit noddy. No! It’s rather larger than the Peugeot 2008 we have at the moment, really very well equipped and finished and with serious poke under the pedal. We both liked it so we’re prepared to go ahead. Currently going through the G99 process – which checks to see if UKPN happy to have this house connected to their local grid. Well, I would hope so, as we already have Solar PV which I am – obviously – hoping will charge the car’s battery at least some of the time.

Watch this space.

I’ve also looked in to Solar PV optimisers – but that’s a separate post.

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