My high power and cheap solar system

[Branko]

It was not easy for build (two months), but it now works.
It is not finished yet (it is first year of experiments), and yet need improvement.
You can found detail here:
http://free-ri.htnet.hr/Branko/index.html

[bitRAKE]

Storing energy in water is a very good solution. I read your pages a couple days ago and wonder how might heat transfer to water be improved. The insulation slows heat transfer, but is needed to protect heat already in the water. Increasing the surface area certainly must help in this design. Another solution seems to be focus of solar input. If the water becomes saturated with heat too quickly then a larger storage tank would be the solution.

Both methods can be used together with a heat exchanger between the two cycles. Concentrating solar collector boils water or another liquid. Hot liquid warms reservoir water through heat exchanger. Benefits are higher energy storage during times of low light and lower heat loss.

I look forward to hearing of your experience and ideas.

[bitRAKE]

I've been giving this some more thought: how about some type of heat pipe (http://en.wikipedia.org/wiki/Heat_pipe) between the solar concentrator and the water tank? No moving parts, can be designed to virtually work in one direction, high energy transfer rate, larger range of operating temperature - damn, seems like a winner.

We just need some satelite dishes, aluminum foil, an underground lake and some large copper pipe and we have a powerplant. (c:

[Branko]

I post details on another part of this forum:
Last year (I only catch after-summer sun, because 2 months build works). It has temperature 25 C. Last week it was 12 C. Water from pipe was 9 C. All winter was about 5 C more than in pipe (it was good for water heaters, but not for heating leaving space). This summer I will know more. Right now is sunny week, and in collector was from 35 to 40 C (pump work is about 6 hour/day for collecting), and yesterday was 16 C in my thank (4 C more). For 1 C temperature, now I need 2 days (sunny day in April, air temperature from 14 to 18 C). It is 24000 liters of water in tank. I will put more when summer comes. Every 1 C is around 30 KWh of energy (if I collect 4 C, it is around 120 kWh). I think it is very nice! I can't wait summer...(and next winter too). Energy bill will tell me the truth.

[tinu]

Branko,

I wonder if I made some computation errors and by no means I am saying that your idea and installation are bad. On contrary, I appreciate them a lot. However, here is the math, which shows some limitations and which unfortunately does not look as good as I would like to:
24000 liters of water takes 24 Mcal (Megacalories) to be heated by 1Celsius. Let?s assume that the whole reservoir can be safely heated 70 Celsius degrees. (I.e. you start at 20Celsius and end at 90Celsius or start at 10Celsius and end at 80Celsius). This would store about 1680 Mcal, which is, of course, 1,68Gcal (Gicacalories).
Now, the bad news is that 1Gcal is about 40Euros or less in the country I come from, including all other costs (maintenance, delivery, loses etc). This would imply that the system is storing and later on it will be providing thermal energy not higher than 70-80Euros per year, at best. I find it insufficient to motivate building such a large installation. Things can be seen different if the system is to be used in remote areas or if one strictly wants to promote/use 100% clear energy. However, judging by the figures above, I suggest that photovoltaic panels and electric storage may provide a more economical alternative and it surely would not require such a large tank and pipes/plumbing.

I have to say that I fully understand also your reasoning and excitement. 30 KWh of energy is quite a lot (and it is expensive too in some countries) if electric heating is to be used. But it is much cheaper to use diesel, methane and/or other petroleum derivatives for heating or even an electrical heat pump that is widely available these days.

Looking forward to hear your thoughts,

Tinu