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Tuesday, 21 June 2011

Solar panels

In response to a comment on my previous post from kcm:

Our installation got off to a good start on the day before it was planned as the electrician turned up and asked if he could start his bit of the work early. The electric bit is quite straightforward. It involves running a cable from the roof outside the house in trunking and into the house near the fuse box. Nothing goes into the electricity meter.

Provided you've got a spare slot in the fuse box - called consumer units these days - it is straightforward. I think if you don't have they can add something on to it fairly easily. There is a big red switch with all sorts of warning notices on it as if you're doing any electrical work in the house the solar panels need to be isolated as well. Above that there's a small meter - which looks like the electricity meter which your electricity company reads. This can tell you how much you've generated and how much you've used yourself.

Maximum output from our panels is 2.5kw and we've generated 60.2kw since last Wednesday in relatively dull conditions. We've used 48kw. No one needs to come and read this meter as it transmits the data to the company via the mobile phone network. In our case what electricity we use we get free and what we don't use the company gets paid for by the government/energy company as it feeds back into the national grid. If you pay for your panels then you get paid for what you generate but don't use by a corresponding reduction in your bill or by direct payment - not sure quite how that works as it didn't apply in our case.

Apart from the meter and the switch there is what is called an inverter in the loft which converts direct current to alternating current. This is about half the size of the average microwave. Then there are panels on the roof which slot into metal tracks so that if one needs replacing it can be taken out and replaced. There is no need to take the roof apart or any tiles off for that matter. I think - but I don't know as I didn't watch - that they drill through the tiles into the beams of the roof so that the panels are well and truly anchored and no the roof won't leak afterwards - I asked.

The only mess involved was brick dust in the hall where the electrician had been working which he swept up and some brick dust outside which quickly blew away and I've found the odd screw in amongst our slate on the front garden. They drilled holes in the wall outside so that they could insert steel eyes by which to anchor their portable scaffolding - though they did ask first if it was ok and they've filled them in again - well I assume they have as I can't find them!

The problem we had with ours was that on the day it was supposed to be done - last Tuesday - the guys doing it didn't turn up until lunch time because they'd been given the wrong panels and equipment and then when they arrived with the right stuff and measured the roof they found they couldn't arrange the panels how they'd been told to. That necessitated a manager coming out and telling them it was all right to put them the other way round - portrait instead of landscape. I laid down the law to the manager - this was 2.00pm - and said because of MJR's recent operation I did not want them doing the work that day as it meant they'd be working into the evening.

The manager in the end was very grovelly and agreed that it would be done the next day. The next day they turned up early and got straight on with the work. By 11.00am they'd just got to put the panels on and they were waiting for another gang to finish with the pulley system they needed - 'elf and safety! In the end it was the wrong one when it turned up but there were about six men here by that time and the panels were put on. So the problems were caused by lack of organisation by the company itself not by any unwillingness to work on the part of the people involved.

I must say that in spite of the organisational problems I was very impressed with the attitude of the people doing the job as they worked hard and didn't keep stopping for breaks and clearly knew exactly what they were doing. Mess created was an absolute minimum. There was a fair amount of noise but for a relatively short space of time. They reckon they can do the job normally by about 1.30pm if they start at 9.00am.

I've seen solar panels on houses which face East/West - in fact I can see one if I look out of the window now so I'm not sure how critical the direction is. What is more important I think is whether your roof is a plain straightforward roof with no little gables or windows and it mustn't be hip-ended - i.e. coming to a point in the middle. They want the biggest expanse of roof possible. It is not just how much sunlight I think but whether or not your roof is always in shadow since we are generating at the moment - only about 0.9kw - even though it is dull and cloudy and the sun isn't actually visible. It basically just has to be light but to work at full capacity it needs sunlight.

It's worth looking on even if you don't think your house is suitable.


kcm said...

Thanks, Jilly. That's most useful and interesting. We'll have to see what Home Sun have to say about our roof.

Jilly said...

I'll keep my fingers crossed for you!