Still Slating

We are still slating the roof, as the weather permits. We are solidly into Autumn, so it is cooler and the weather is wetter, but we have not lost many days so far. We would not want it to get much colder, so it is a bit of a race against time. We probably have another 8 days work left on the north-facing roof, plus the time we will ned to flash the solar panels on the south side and to fit the ridge tiles.

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We are working much more quickly now and have a good system going where one of us can pass slates up to the other one up until 9 courses from the top, then use the short roof ladder to get those upper courses done. It is much quicker to move the short ladders than one long one and so far we have not cracked any slates through resting ladders on slated roof.

We installed a second roof slate, this time for our stove flue-pipe. The latter will be 6” inside, 8” outside diameter, so we got one with a 219mm tube. It arrived well folded up and-battered looking, we got it straightened out and waited until we got the slates up to where we wanted the bottom of the lead slate to line up. We used the jigsaw to cut out the sarking to the diameter of the tube +75mm all round. So a comparatively enormous hole. Fitting the slate turned out to be simple because it lined up nicely and I was able to use full sized slates and slate-and-halves without any cutting. The top edge was just below the ridge so we fitted the top-most course of slates above, directly onto the lead. The ridge tiles will cover the top edge, all very simple and neat. The areas we have slated have been fully tested and we have not seen any leakage at all, so we have the whole east wing and chunks of the north wing properly weathertight. I also understand why we had so many leaks through the membrane – rain was ponding up above the battens we used to hold the membrane down, the water was running through nail holes to the sarking and wicking down the underside of the membrane. When the water got down to the rooflights, there was no membrane left and the water dripped off the sarking immediately above.

Preparing for PV panels

Our building warrant expects us to put a row of PV panels across our south-facing roof overlooking the courtyard. Now was the time to do something because we cannot finish the roof without the panels. We slated along the lower half of the roof, along the entire 23m+ length, taking in the five rooflights and getting the slates to the tops, so we could completely install the flashing kits. We worked right to the bottom corner of the west end of the roof and left the slates on the diagonal, to just cover the 5^th rooflight. We will probably nail OSB up over the edge of the slates over the winter, to preserve the breather membrane until we get the west wing roof on.

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We contacted 6 companies, some very local and others around Edinburgh, saying we wanted a 4kWp array with microinverters, mounted directly on the sarking boards/breather membrane. We explained that longer term, we wanted an integrated system with the ASHP, woodburner and thermal store.

Five responded. One, Install Solar from Livingston, were the first to visit us on site. The person was surprisingly helpful and appeared to live, breathe and eat solar panels. He persuaded us to go for as many panels as would fit, he thought 20 at 310Wp each – around 6kWp – because the panels are relatively cheap i.e half as much capacity again for around £1,000. He also suggested 4.7kWh-worth of batteries because it makes it easier to make full use of all the electricity generated. We would still divert unused electricity to heat water, but should be able to cover evening use of electricity – lighting etc.. He thought we did not need microinverters because the shading of panels at each end would be gradual and regular and should be covered by bypass diodes in the panels. These prevent a panel that is shaded from stopping the other panels from working fully. Finally he said that they did not do heat pumps etc., but thought it was a good plan. He suggested a phase-change thermal store rather than just hot water. It was a very useful visit and we even had in the back of our minds putting extra panels on the west wing, to get earlier morning and later evening sun. Two days later, Aberdeen Solar visited us. They suggested a set-up that was exactly what we asked for, but they seemed resistant to going from 16 to 20 panels. Novus Elements were interested in quoting but did not visit. They were flexible and were happy to quote for 20 panels. Two companies did respond but did not react in time. So we ended up with three sensible quotes. After only a day or two, we went for the Install Solar quote, including the batteries. They said they could install the system on the following Wednesday. It was all a bit cheaper than we were expecting, I expect the recent demise of FIT meant the industry is mostly below capacity.