Solar panels

DSC_8807

We’ve finally got round to having solar PV panels installed. As you can see form the picture above.

The price of solar has been coming down, but still it isn’t economically viable without subsidy for us. However, the subsidy makes it clearly economically beneficial (to us) so combined with a guess that the ecological payback, which is far less clear, might be acceptable too, we went ahead. What finally tipped us into doing something was (a) the government announcing the end of the fat subsidy regime (of which more anon) and (b) a local group organising an installation firm for the village.

Economics

Let’s talk about the economics first. In the UK, this is all about the subsidy regime which is currently £0.433 / kWh for solar PV retrofitted, for an installation less than 4 kW. That compares with a cost of electricity from the mains per kWh (inc VAT) of ~£0.25-0.12 (depending on supplier, tier, phase of the moon, whatever). But since our energy needs are vastly less than our installed 3.5 kW, and we’re usually out during the day, most of the time we won’t be saving that money, instead we’ll be feeding stuff back into the grid. And I don’t really know what we get paid for that – casual conversation said £0.02/kWh, this says… its complicated. I can’t even remember if we did the 50:50 “deeming” deal spoken about there.

With all that, the payback time was put to us as being about 9 years. Since it cost ~£10k, that implies generating about £1k/year of power, which certainly exceeds our current bill. Given that price depends so heavily on the subsidy, these calculations only apply to the UK. We scrambled to get our installation in place before December 12th, when the subsidy was due to ~halve, but Solar tariff cut plan ruled legally flawed says that maybe that won’t be the cut-off date. It will be soon, though. Which is probably correct: the price is currently set too high, and its a cash cow for people with the installation.

Our system

DSC_8955-sunny-beam We have 15 Trina panels which are supposed to produce around 220-240 W each (so ~3.3 kW), a 3.5 kW inverter (Schuco) in the loft, wires leading down the the electricity cupboard, several isolator switches, and a meter thingy which we need to read sometimes and send in, in order to get our subsidy. Note that to get the good subsidy, you need a system < 4 kW, but we'd have struggled to get more panels on our (fairly small) roof. We were originally going to have 16, and a 4 kW inverter, but apparently the 4 kW ones are in short supply.

Most excitingly, we have a "sunny beam" Bluetooth power meter, which talks to the inverter in the loft, and draws pretty graphs of your power generated and £'s saved. Miranda in particular loves it, and consults it every day. She did want to take it away with her on a recent visit elsewhere, but we explained that Bluetooth doesn't have a range of 100 km.

Bronte Captial (that isn’t his best post on Trina, search around, you’ll find the rest) isn’t too impressed with Trina as an investment – indeed, he thinks that all panel makers are due to get squeezed. But that doesn’t affect me as a buyer.

The ecologics

Well, I dunno really. I’m assuming that, since it has to be subsidised, the total unsubsidised economic value must be negative. And therefore, using economics as a proxy for ecologics, the ecological value must be negative too? That is less clear; after all, we don’t cost externalities into our electricity costs.

Refs

* Upbeat energy were the people who did us, and others in the village. They seemed quite competent and got the job done.
* The eCoton posting with links to some (probably now obsolete) information.
* Misc pics of the installation; more.
* BP exits solar says Timmy. Shades of Bronte.