Theres much more to an efficient solar heating system than your diy ideas
Please elaborate as you seem to know enough to know there is more to it ...
I would no longer go anywhere near a thermal store for small scale domestic use.
Why? (As trev asked above I know, but would be most interesting as to why).
Am interested in both solar and themal stores.
Like trev I would not consider paying for one of the professional systems of solar but it would be fun to play around (interetsingly I was considering paying for a thermal store at some point but oilman's comments made me think twice). Actually, with solar I could possibly try one of the evacuated tube systems from Navitron.org.uk which are not too pricey. In any case they do have a great section in their
installation manual, which is more like a product brochure than an installation manual, but still really detailed, which explains their take on the development of evacuated tube technology - they claim it was actually developed by some chinese university (beijing I hintk) - and the wording seems to suggest this is all evacuated tube technology not just the one they use. If Navitron are to be believed then all evacuated tube systems are based on this Chinese template making a criticism by an installer that Navitron were "Chinese rubbish", that I think someone on this forum reported, a bit beside the point.
For those interested trev was referring to a flat plate collector which I believe does not collect as well in winter as evacuated tube but would work well in summer. The link he was referring to was probably
this. There is another similar one at
diydata.
I haven't been able to find any good threads on this site about making your own solar hot water collector; I mean they don't even link to any of the great resources elsewhere on the web - I did see one post that mentioned he had been inspired by some links he got off this forum but couldn't find the post he got the links from. I have seen a few threads with people who claim to have built a system but sadly I haven't seen any reports on the details of how they worked/how they did it. Anyway, a good place to find links on real DIY solar heating (i.e. building it yourself), as well as just self install, and lots of other good "energy saving" stuff is at
builditsolar.com.
From my limited understanding so far the one thing you really have to be careful with following some of these plans is that sometimes they don't put in any saftety margin for when the water can boil and the steam get to really high temps. Desiging some pressure release into the system is probably a good idea.
The above notwithstanding, making your own evacuated tube would be a fun project I think. Maybe start simple, do a test with a bottle and a cork with a hole through and two tubes in - one the collector the other to create the vacuum which you could then seal off ... oh yeah you'd have to be careful for implosions or explosions...
Well, that is at the extreme end, as said above if Navitron are right there was some serious and genuinely professional development put into evacuated tube design (but now the patent is out you could try and copy it at home with care) - I wouldn't be surprised however if alot of the flat plate systems aren't extensions of someone's eccentric DIY idea.
Well with flat plate DIY you should be able to get something useful without major experimentation (as people have already explained in detail how they've done it). So on the contrary Trev if you read those plans they say in this technology at least you should be able to get very near if not better than ready made commercial units.
It is a pity solar systems cost so much and why on earth are government grants only for professional installers? If you can make something yourself, say out of freecycled stuff (as someone mentioned he did mostly) and even if it only gives you 25% of your hot water in summer (I think most of the DIYers I read got more than that), then you should get some kind of benefit from the authorities concerned with energy saving (like the German council tax reduction for instance - I wonder if htey say you can only get it if your system is professionally installed, or does it just have to meet some energy efficiency test - interesintg research to do) - instead the money is lining the pockets of quick thinking solar startups many of which are probably making unnatural margins. Trev and gas4you, not just about increasing subsidies but rationalising their allocation - if a company charges ridiculous amounts then the subsidy can be alot and there is little incentive to the home owner - it probably both drives average subsidy prices up and reduces demand for solar power. If you promote more thrifty systems in the first place and pay smaller subsidies towards those you probably get far bigger energy savings. So really ironic that the Solar Trade Association lobbying for more grants - the high prices of their members are not helping. Renewable microgeneration seems to have a good pedigree of genuinely committed greeny types doing inventive and actually useful things in a simple manner. The government could deal on this level - like funding research into how such items could be made with more standardised materials (for instance the CAT has a good book on solar DIY but you have to pay for it - why doesn't the gov fund them so they can give the books away free), as well as or instead of with bodies like the Solar Trade Association.
And of course, a DIYer could potentially install a manufactured.system to the same level or better than a professional installer, and a professional installer could install it worse than a DIYer, so why not just have a governement inspection (and overall energy efficiency assessment) of completed work to qualify for the grant (that would trap the rogue professional installers too)??
Still, it still might be not good environmentally speaking to have any encouragement of solar - maybe the material and installation costs in energy will outweigh any savings - I haven't seen any sutdies, I'm sure there are some. But the freecycle route would be better, and one would think that using more readily available manufactured new parts is more energy efficient than systems which use specialised manufactured parts.
One big advantage of making it yourself as well as installation costs would be ease of repair as you have the parts readily available. If one or more of your tubes broke in an evac tube system (cos tiles fell on them or something) and the manufacturer made your model obsolete you'd have to replace the whole thing.
p.s. also practice of collecting heat might also be used in other situations such as recovering heat from drains or vents, and once you get an understanding of the basics you could apply it to many situations as you think of it (builditsolar had some good links on drain heat recovery - seems silly to do solar and not do this) - the pluming could get very complicated though!
