Worth getting solar pv?
in Green & ethical MoneySaving
21 replies 506 views
There are some very knowledgeable people on this forum and I’d be grateful for your thoughts. My gas boiler is ancient and I’m planning to replace it with an air source heat pump. I’m wondering whether it’s also worth getting solar pv. I have an end terrace house with a hipped roof so the surfaces are quite small and more-or-less triangular so I don’t think I’d be able to fit many panels on it. The front of the house faces south (roof about 5m wide at widest point) and the side faces west (8-9m wide). I’m in NE England. My aims are reducing my carbon footprint and hopefully reducing my energy costs. Am I likely to generate enough electricity to make the outlay worthwhile?
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I should also warn you that replacing gas heating with an ASHP will increase your energy costs.
The bulk of your PV generation will be in the warmer months, and for myself, with E/W panels, our winter gen is even smaller (it's a summer specialist), however we still export at times in the winter months, and when that happens, on goes our small A/C unit to reduce GCH. We've also been able to use the small unit for all house heating since mid Mch, and by late Mch almost all heating has been done from PV generation - though of course the amount of heat needed, even in a cold Apr and May, is tiny compared to Jan/Feb.
So, PV won't give you enough juice in the winter, but it'll still contribute, and of course do what PV does the rest of the year.
PS. Haven't seen nor mentioned these for ages, by if you Google Trienergia, then you may find 'triangular' solar panels, which can be combined for install on roofs with a sloping edge, or full hip, just like you are thinking off. They used to be a bit more expensive, but allowed for a smidge more Wp to be installed, but more importantly, might look nicer.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 2.5kw inverter. 28MWh generated, long-term average 2.6 Os.
So my solar panels are managing to cover the rest of the house demand for electricity but are barely touching the requirement of the ASHP. One good thing is that on most days I have heated the water in my cylinder by directing the surplus electricity to my immersion heater so the ASHP would have used more power if I had not been doing that. I am suing the immersion heater because its power requirement is better matched to my panels than that of the heat pump and it allows me to get the tank up to about 75 C whilst the heat pump stops at 55 C. .