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| sak |
 Posted: Wed Jan 23, 2008 3:41 pm Post subject: Taping solar energy |
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Forum Sophomore
Joined: 21 Sep 2007
Posts: 125
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| Planning to set up a solar power kit for my house. Does some one give me some tips/ check points regarding getting solar panel, a power management system to minimize power consumption form the state supply, storing charge in a battery and so on… |
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| Megabrain |
| Posted: Mon Jan 28, 2008 6:42 am Post subject: |
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Forum Sophomore
Joined: 24 Jan 2008
Posts: 122
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The first thing is how much energy do you want to extract?
Sun directly overhead throws around 1KW/ sqr metre on the ground. Solar cells will produce about 100watts/sq metre (check this though..)
THe most efficient use is made by using the infrared heat to raise the temperature of water.
1 Calorie is about 4.2 joules or (watt seconds) if you can warm 200Litres of water by 20 degrees (easy in a day) then you have saved 20*200,000 or 4 million calories 16million watt/seconds then you will have saved about 4.6 killowatt hours, say 2 square metres for around 4 hours = 8KWH but only 50% efficient. Whereas solarcells over the same area produce around 0.8 Kilowatt hours.
solar cells are expensive, you can make better savings by using more energy efficient appliances/lights.
The figures above are approximate from memory but they are ball park.
A couple of old central heating radiators painted black and enclosed (to prevent wind cooling, you make the kit yourself. If you are in a climate where frost at night is a problem, then the radiators need anti-freeze or a light oil. |
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| sak |
| Posted: Mon Jan 28, 2008 7:29 pm Post subject: |
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Forum Sophomore
Joined: 21 Sep 2007
Posts: 125
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That was quiet interesting & informative, Thanks.
I was looking deep into electricity production. |
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| Bunbury |
| Posted: Mon Jan 28, 2008 8:17 pm Post subject: |
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Forum Ph.D.
Joined: 26 Sep 2007
Posts: 743
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You will probably need a small pump to circulate the working fluid, since the "hot" part of the circuit will most likely be above the "cold" part (i.e. on the roof). It might make sense to have a small photovoltaic panel to power the pump.
Then you need an indoor heat exchanger (coil in tank) to heat your domestic hot water. |
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| sak |
| Posted: Fri Feb 01, 2008 5:14 am Post subject: |
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Forum Sophomore
Joined: 21 Sep 2007
Posts: 125
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| Good, exploiting my imagination! |
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| Pumblechook |
| Posted: Tue Feb 05, 2008 2:12 pm Post subject: |
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Forum Freshman
Joined: 05 Dec 2007
Posts: 44
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100 W per sq mtere will be the peak. The average over a full year is much less...more like 10 W. (real figure from a real installation). Clearly you can never get more than 50 W average as it is dark half the time and the peak is only reached in bright sunlight when the Sun is square on to the panels.
Basically the panels, batteries and other equipment never pay for themselves. |
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