Solar water heating

wizzards

Am thinking about installing integrated solar panels to heat hot water. As I need a new roof anyway I was thinking that scaffolding would be there and integrated panels would look better and could be done at the same time as the re-roof. I am thinking maybe some from Worcester Bosh or similar panels which come with a flashing kit for integrating into most tiled roofs. I am wondering if anyone on this forum has anyone done this type of install and their experiences and anything I need to watch out for,

The house is semi detached 1930 ish facing directly south on the roof I plan to install on. Just wonder also if people have experience of this and whether you do really get a good amount of hot water from this type of install. I looked at PV panels but didn't see that they would really make a great saving. Also the advantage of the panels that heat the hot water is that during the day when usage is low they heat up the water ready for peak usage in the evening. To me this seems to have great advantage over PV.

agentk

pv with diversion device and a hot water tank maybe cheaper.

Martyn1981

Nothing wrong with solar thermal at all, but from an investment point of view it'll lose to PV every time since leccy has a greater value than gas.

You may be spending £3k or so on ST to save £100 on water heating, whereas £5k on PV could bring an income/savings of around £600 and on top of that water heating savings of £50 to £80 a year with a diversionary device.

PV will take up more roof space though.

Mart.

Martyn1981

wizzards wrote: »

I am thinking maybe some from Worcester Bosh or similar panels which come with a flashing kit for integrating into most tiled roofs. I am wondering if anyone on this forum has anyone done this type of install and their experiences and anything I need to watch out for,

A thought. There are quite a few people on the Navitron discussion forum that have ST, some have installed themselves. Also the site 'owners' sell panels, and I think (may be wrong) that there are videos somewhere to show you how to install.

On the navitron discussion threads the same conclusion has been reached that PV will bring a greater financial return than ST, whilst providing a reasonable amount of hot water via a diversionary device. Though the energy payback on ST is very good (energy produced v's energy consumed making the equipment).

Mart.

ed110220

Hi,

are you sure you've understood the basics of solar PV? Because I think it beats solar thermal for every plausible scenario I can think of on financial and environmental grounds.

A few things to think of:-

* you get paid for every kilowatt hour you produce from solar PV, even if you use it yourself.

* you get paid in addition a lower rate for every kilowatt hour you export to the grid. This displaces fossil fuel generation.

* electricity is a lot more expensive and useful than hot water. You can of course use solar PV electricity to heat your hot water, but to get enough hot water over as much of the year as possible from solar thermal, you'll be producing much more hot water in the summer than you can possibly use, and unlike electricity can't sell it to someone else to use.

Ed

zeupater

Hi

Yes, but no, but yes, but ... We've got both pv and thermal (although not integrated) so here's a different take ...

If you're limited by roof size then the higher efficiency of thermal (in terms of kWh.t/year/sqm) will come in handy ... and if you want to extend the solar heating period you'll really need vacuum tubes .... then again, if you want to maximise returns on investment, FiT is better than RHI and electricity is more flexible (in how you can use it) ... our thermal collectors have a footprint similar to four pv panels and provide almost all of our DHW from ~March to ~November and still contributes something in the worst months by pre-heating mains water in the cylinder prior to GCH DHW heating ...

Whichever you go for you should really look at your hot water storage capacity and size it to cope with a couple of consecutive dull days and have a whole house TMV (thermostatic mixing valve) installed .... we've currently got a full cylinder of extremely hot DHW which would probably see us most of the way towards next weekend if necessary ...

Both flat panel thermal and pv can be roof integrated, which can reduce your materials costs if you need to replace all of the existing tiles - however, pv efficiency reduces as panel temperatures rise and integrated panels tend to operate a few degrees warmer, so improved aesthetics will reduce the FiT returns a little.

It all really depends on how the figures stack up for you on your own usage, roof-area & what's involved in the re-roofing, but with a '30s semi you probably won't have room for both (?), so with the better returns and additional usefulness of electricity you'd probably be much better looking at pv with proportional diversion to DHW ...

Really need much more info for anyone to provide more detailed assistance, but hope this provides a basic insight ...

HTH
Z