solar panels with built-in cylinder

[kpaprod]

How efficient are these type with a cylinder on top of the solar panel like this one from navitron sfd15-58 in England?

I live in London and I plan to use the thermal store version. Was the water hot enough to warrant a TMV?

How much heat loss should I budget for per meter of pipe to the house? I plan to use 10mm insulated plastic pipe which should take 50C hot water.

Has anyone installed one of these types and how did you connect the pipes to your house? Did u put it underground and are there regulations that determine this?

Can I put my pipes from the cylinder above ground along a fence and are there regiulation that say how high above ground?

[Ivan]

The SFD panels are very efficient, but heatloss will be greater in cold weather, due to greater dT. You can put immersion heaters into them, to make it into a year-round, dependable hot water system.

Can't answer the temperature loss question. I guess it depends a lot on flow rate - the faster it flows, the less chance to lose heat.

you'll need to put a mixer valve on the outlet of the SFD panel if you intend to use plastic pipe - the water will reach 100C in sunny weather.

Outdoor pipes are in danger of freezing in cold weather. That's your biggest problem. If you don't draw any hot water overnight, and temperature drops to -5C or so, your pipes will freeze, regardless of how much insulation you have around them. Of course if you are using plastic pipe, it should be possible to use something that is freeze-resistant....but that won't be much consolation when you want a warm shower on a winter morning. I often forget to shut off my outdoor water tap in the winter, and when the pipe freezes, it can be frozen for anything up to a week.

[kpaprod]

Thanks for the info.

The problem of pipes freezing overnight - would it help if I run the hot tap just a bit at regular intervals overnight?

Would underground be better as the ground termperature is constant?

Should I put more insulation round the cylinder in winter?

[Ivan]

Running hot taps regularly during cold nights would work - but it would waste a lot of hot water (pipes cool down very quickly).

Underground would be much better - if you are 18" deep, you'll be frost free even in very cold weather.

More insulation will always reduce heat loss, and therefore improve efficiency, but the cylinder in the integral panels (SFA, SFD and SFH type) is very well insulated. It's a large volume of water so it's quite resistant to temperature change. Somewhere on this forum I did post what the overnight temperature loss of the SFA panel was. You'll have to do a search to find it, because I cannot remember the actual figure.


Ivan