Changing the use of solar panels?

Martyn1981

Cheers Zeup, interesting stuff, if only as a thought / learning exercise. Funnily enough I wasn't actually thinking of using the water, I was thinking ready made hole, slap in a slinky GSHP if big enough. Then in fill as planned anyway.

Quick bit of reading up, and I found that you need approx 10m of trench for each kW of heating needed. Suggesting around 4kW for underfloor heating. So in this example 40 feet approx 12m, would need around 3 'trenches' worth. So depends on width of pool. Plus do I correctly assume that you wouldn't want slinkys too close together as they would reduce each others effectiveness. But I couldn't find a reference to adequate separation distances.

Depth also a concern, but that would depend entirely on the current depth and what is planned afterwards, since overfilling / overtopping would help.

Interesting point you make about the earth transferring heat and water migration. I understand that migration would help in the winter by dispersing the cold, but I was working on your suggestion of supercharging the ground in the summer. For that I would assume (probably wrong) that migration would be the enemy, hence filling the hole with dense solid material, like a giant storage heater.

Anyways, mostly fanciful imaginings from somewhere inside my head, it just seems a shame to fill in a hole if you could put something useful in the bottom first, and as you pointed out, possibly some recycling of existing kit. I'm picturing a 'normal' slinky style GSHP, in a hole that also has some sort of slinky linked to the solar thermal. The solar thermal heats the hole, and supercharges it all summer, whilst the GSHP works normally.

Mart.

murphydog999

Actually I thought Zeu was on about filling it in, not using water!

It's a big area to fill and we were thinking of having a pond built into the centre and the rest of it shuttered, then paved, around the rest of it.

zeupater

Hi

Calculations were for water as it would be a better for heat transfer ..... as for water migration, yes, if it's on a general slope of any form the effect of the heating of the ground would be deminished.

I would have thought that placing anywhere near 40m of ground loop into the area of a 40' pool (assume 15' wide) would likely result in an area of near permafrost resulting in greatly degraded heatpump performance ....

Myself, if the pool was decent I'd leave it there and use it ... if the pool was in a state I'd probably either create a formal pond with a water feature in the middle, probably softening the edges with a limited infill if a less formal shape would look better .... if theres a safety issue (toddlers?) complete infilling could be awkward & messy (source of material?), so I'd look at building a feature area of decking including a pergola structure over the pool, leaving the pool intact for possible future renovation - remember the pool could be a significant added value selling point at a future date even if it's not a particular requirement at the moment.

HTH
Z

Charles_Montlake

I would consider changing the existing cylinder for a solar twin coil cylinder and diverting the warmth from the panels to the cylinder to augment the existing water heating system.

Not an ideal or clever solution but, as they say, every little helps

bris

Charles_Montlake wrote: »

I would consider changing the existing cylinder for a solar twin coil cylinder and diverting the warmth from the panels to the cylinder to augment the existing water heating system.

Not an ideal or clever solution but, as they say, every little helps

That's definitely the best solution, change it to heat the domestic supply. If it was big enough to heat a 40 foot pool it will be big enough to take care of most of your domestic needs. this will save the most money and get the best use of the panels.

zeupater

Hi

Diverting to the H/W system would depend on the panels ... they'll likely be low temperature/low cost panels specifically for pool heating which aren't really very efficient at regularly generating temperatures which are high enough for domestic HW in spring or autumn ..... if not, then 7 efficient panels (~14sqm ?) would create a hugh amount of heat in the summer and would need to be designed to withstand very high stagnation temperatures else you would need an extremely high average hot water demand to avoid either boiling the cylinder contents or dumping hot water to the drain on a regular basis ....

HTH
Z

bris

Thats what heat dump loops are for. Large radiators are placed where they are not need and a valve directs the hot water to them when it is not needed elsewhere. It is all automatic to keep the water flowing a the right temp.

zeupater

bris wrote: »

Thats what heat dump loops are for. Large radiators are placed where they are not need and a valve directs the hot water to them when it is not needed elsewhere. It is all automatic to keep the water flowing a the right temp.

Hi bris

I agree, however most HW installations these days don't have heatdump loops, ours certainly doesn't, it just stagnates when there is no longer a requirement for heat from the HW cylinder and panel water/glycol temperatures rise to around 200C .... If dumping the heat from seven ~2sqm panels at around 70C water temperature in high-summer full sun you would need approximately the same number of radiators for the dump as a small house would have in it's total heating circuit (~>10kW)... you would have the option of modifying and using the heating circuit itself - but then the house would get pretty sweaty on an already hot day ... :D

HTH
Z