Pssst! Wanna see my solar panel pictures?

[darth vadar]

"we have four that get used a lot and waste a lot of clean water"


Are you bragging or complaining ?


If you've suddenly developed a conscience, then why not just use one toilet like the rest of us?

 

[Rohloff_Brompton_Rider]

doesn't matter whether 1 or 4 with two 18/19 year old kids and a wife with weak bladders . would be the same amount of wasted (bloody expensive) clean water. plus i like the idea of being enviro friendly.

 

[Black Sheep]

Sorry if I'm being stupid (probably am)

the system will obviously work best in the summer as thats when we have the most sun / warmth.

you say there is car anti-freeze in the system (good idea) does that mean it's a sealed system that somehow transfers it's heat to your regular domestic water supply?

 

[Globalti]

Sorry if I'm being stupid (probably am)

the system will obviously work best in the summer as thats when we have the most sun / warmth.

you say there is car anti-freeze in the system (good idea) does that mean it's a sealed system that somehow transfers it's heat to your regular domestic water supply?

Er, yes. The panel consists of 20 evacuated tubes, which heat a liquid (water and anti-freeze) that circulates though the coil in the cylinder. This is a long piece of copper tube coiled up inside the cylinder, which is used to store water before the boiler heats it. This is plumbed above and in tandem with the house cylinder, so any heat that the tubes collect is used to pre-heat the water entering the house, taking over from the gas boiler. Anti-freeze is needed because the temperature in the manifold at the ends of the tubes reaches night time temperature, which has been as low as minus 10 recently.

In summer I expect the tubes to heat the water in the cylinder up to 60 degrees and possibly even hotter, at which time I will need to dump the excess heat. Some people use an old radiator in the attic but I plan to divert the extra downstairs to the main house cylinder, which we will soon enlarge. You can see an illustration of a fancy version of the same thing here: http://www.viridians...for_Housing.htm

 

[Black Sheep]

So its a hot water in the coil heats a tank of water that is actually used system then?

similar to passing steam back through a steam loco's boiler to ''superheat'' it (or to put it another way, I get the principle)

So you plan to divert the un-needed hot water in the summer into the main hot water tank for the house making it a larger system to keep the highest temp for the system as low as you can?

fair enough.

 

[Globalti]

Yes, the coil will pre-heat the cold water entering the house in the first cylinder, from where it will pass to the second (main) cylinder where the boiler will raise it to 60C. It's been running through both cylinders for a couple of years now, we just haven't been heating the coil. If we add a second set of tubes we will get enough collecting capacity to heat the first cylinder fully then dump the remaining heat into the second, main cylinder.

 

[Jezston]

In summer I expect the tubes to heat the water in the cylinder up to 60 degrees and possibly even hotter, at which time I will need to dump the excess heat.

Stoopid question I may expect, but is there any way to turn that excess heat into electricity and stored?

 

[Globalti]

Not that I know of. You'd do better to have some PV panels and charge batteries with them; I have a neighbour who does that and his car is filled with milk float batteries giving him about 60 miles range.

 

[Night Train]

Not that I know of. You'd do better to have some PV panels and charge batteries with them; I have a neighbour who does that and his car is filled with milk float batteries giving him about 60 miles range.

That must be some car with 60mile range on milk float batteries.

I like what you have done with the solar hot water system and I am seriously considering doing myself having seen how you have done it. I just don't have a loft or a tank so will have to figure a system around that.

I thought about having a number of storage tanks so that, during summer, when one tank is hot the heating fluid is diverted to heat the next tank and so on. But I couldn't think of what to do with 5000 gallons of hot water in summer!

I would also want PV as I should be able to charge my planned electric car with it using grid storage. Given 10sqm of south facing roof slope at 45deg I might get a reasonable output.

Rain water storage is another possible as I can tank the water in the basement for pumping up stairs using the PV panels.

Can't afford to do it yet though.

 

[mgarl10024]

Great job.

I've been tempted to do something similar, but not quite sure what.
We have a south facing roof which gets very hot in the summer, but I'm not sure whether water heating like yours or electric (PV) panels will give a greater return. I suspect yours gives a much more instant return, and those PV panels contain a large number of nasties which makes my green senses feel uneasy.

Will follow your updates with interest!

 

[twentysix by twentyfive]

Wonderful job there. Just on potentially silly question. How does the weatherproofness of the roof remain intact? That would be my biggest worry I think.

Oh - as for storing the excess heat - if you could get it very hot and under pressure then you could use a Steam Engine to charge some batteries. But for good efficiencies you would need a scaldingly high temperature and a nastily high pressure. But it is possible in principle.

 

[Globalti]

Wonderful job there. Just on potentially silly question. How does the weatherproofness of the roof remain intact? That would be my biggest worry I think.

This was also my concern; I simply did not want to be drilling or cutting the tiles. This panel is held on by four metre-long stainless steel straps, which bolt to each corner and are thin enough to slip under the tiles and then fold around battens fixed across the rafters. The 10mm pipes, even with a layer of insulation, fit through grooves that I ground in the bottom edges of the tiles, so again the roof remains completely intact.

 

[Arch]

But I couldn't think of what to do with 5000 gallons of hot water in summer!

Have a garden party. That'd make a lot of tea!

Globalti, could the excess heat power a Stirling engine? (and hence generate power)

http://en.wikipedia.org/wiki/Stirling_engine

 

[Night Train]

Have a garden party. That'd make a lot of tea!

You, me, hot tub!

 

[Arch]

You, me, hot tub!