The best way to understand the intricacies of a simple home lighting using solar is to make one.
Let's start with "Solar Constant" Solar constant is a misnomer for it is not really a constant. The value varies between 1350 to 1370 W/sq. meter. Solar radiation received at any given moment is solar constant times the earth's cross sectional area. Since only half the spherical area is exposed to the sun, the area is Pi * Diameter Squared / 4. Where Diameter is earth's diameter. Average solar power per unit area is 1/4 of the solar constant.
So 1350/4 =340W/m2. Out of this amount 30% is reflected back to the space and 24%-25% is absorbed by the atmosphere, only 45% reaches the Earth.
340 * 0.45 = 153 watts/m2 or 153/3.282 =14W/Sq. Foot.
Now consider the solar panel efficiency of 15%. One square foot of solar panel will have an output of 14 * 0.15 = 2.1W. This may be close to the peak power output say for example at 12PM, Clean crystaline panels and bright sunlight.
Now for LED lighting, the solar energy has to be stored and this media would be lead acid battery. 12V, 6AH battery at the charge rate of say 1/10 the capacity, would need 14.4V @ 600mA, which would mean one would need 8.64 Watts or approximately 2 * 2 =4 Sq. foot of Solar panel. This panel with the help of series parallel combination of PV cells and a switched mode Lead Acid battery charger would help charge the battery in approximately10 hours. I will consider the charger efficiency as part of the design in part 2.
10W worth of LED lights, from 72 VAH battery would give us 7 hours of light. LED lights being bright, we can even split the lights into three, three watt lights.
Panels retail today for about Rs. 100/watt. So one is looking at Rs. 800-1000/- in panels and may be another Rs. 500/- for the chargers. We will have to make our own LED lighting.
This is the first part that figures out the size of the panels required for a 10W LED project. In the next few days, I will write about both the battery charger and the LED driver.
自做自受 2014-9-26 22:30
用户1447804 2014-9-26 16:43
用户1678053 2014-9-26 09:34
看看
用户1406868 2012-10-22 20:59
用户3720739 2010-4-14 12:59
Great Article!!
Great to see you here, Rampa :-)
We can go a long way with ourcommonmeeting grounds and memories of professional interests,college, friendsetc
I am at www.smartmicrosystems.biz
Shiv
用户3800148 2009-11-21 02:36
Wow! It's great site. I'm very much pleased to read this article. It is really awesome and helpful too. Very useful information about lighting our home.Thanks for such a great article.
=============================================
alex
<a href="
" rel="dofollow">Home Lighting</a>
用户3800148 2009-11-21 02:33
Wow! It's great site. I'm very much pleased to read this article. It is really awesome and helpful too. Very useful information about lighting our home.Thanks for such a great article.
=============================================
alex
[url="
"]Home Lighting[/url]
用户3671106 2009-10-9 20:41
I am interested in small wind mill cum solar power system at a very low cost in remote area in india
Can u provide details of supplier in india and subsidy contact details.
Ram Anant comments: It would be good to know what your budget is. Combination of solar and wind will require energy storage mechanism. It would be Lead Acid batteries. Once you specify what kind of run times and load you have in mind, I can recommend the combination.
Also the prices of solar power pwer watt is dropping; whereas the prices of windmill are holding up fairly well. So from the standpoint of economics, just solar and storage may make sense.
Please let me know your power requirements so we can go from there.