PV Gap

Dan Said:

What info do I need to find out how long it will take for a solar panel to recharge a battery?

We Answered:

Battery could be 500 amp-hours, but that is a very large battery. A large auto battery is about 70–100 amp-hours. Or the 500 amps could be a max current rating, and have nothing to do with capacity.

How big is it physically? If it is ordinary car battery size, I'd say it is 70 amp hours.

If it really is 500 amp-hours, and the panel delivers 60W / 15v = 4 amps (it takes 15 volts to charge a 12 volt lead-acid battery), then:

500 amp-hours / 4 amps = 125 hours to charge it. (70 amp-hrs, this would be 18 hours) But at that slow a rate, barely a trickle charge, it could take significantly longer than the 125 hours. Be sure you have a good 5 amp diode between the array and the battery so that the battery doesn't discharge through the solar array when the sun goes down.

Note that, as mentioned above, the array has to deliver 15 volts plus the diode drop, say 16 volts, before the battery charges at all. You may get this only with a very bright sun.

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Marion Said:

Can anyone tell me how to run an electric water pump from a solar panel?

We Answered:

First you have to know the wattage of your water pump.
Then you have to determine how many solar panels will be needed to run the pump or you may find it cheaper to undersized the solar system but provide it with a battery back up for a reasonable length of time. If the time extends beyond your plan then you will not be able to run the pump all day.

So you may additionally need to know how long each day you will need to run the pump.

Photovoltaic panels are DC electricity as would be any battery backup, but the pump is no doubt 220 AC. This means you will need an inverter to make the conversion.

Here is one example of a system with a battery back up: http://www.mrsolar.com/page/msos/CTGY/ba…

James Said:

Solar Panel info needed?

We Answered:

A 150-watt rating means the panel will produce 150 watts as long as the standard conditions are maintained. So if you had this bright sun and cool temperatures for 6 hours, the panel would deliver 150 x 6 = 900 watt hours, or a little shy of 1 kilowatt-hour. Kilowatt-hours (kWh) is the reading on your electric bill.

However, like most advertising, the 150-watt number is not realistic. They assume that the air surrounding the panel is very cold. 125 watts is a better number to use for this size of panel for engineering purposes.

Roger Said:

need to build a solar panel or two to heat my green house.have two 6 foot glass doors,need info on how do i?

We Answered:

just get a lot of 5 gallon buckets and paint them black then fill them with water and stack them along the walls of the greenhouse below the plant shelves. Will accomplish the same thing and give you heat all night when you need it by soaking up the heat when you have too much and releasing it at night when you need it.
Save the doors for a cold frame for next spring and sell Vegetable plants.

Andrew Said:

where will i find solar panel info for free?

We Answered:

Hey Bandit, there are some really good websites on the subject, my favorites are operated by non profit groups, I will list them below. As the old saying goes, the best things in life are free, but there is one really good exception to that rule. Home Power Magazine is the only periodical that gets into the nuts and bolts of home grown energy. We started reading it 12 years ago. A couple years after that we attended an energy fair that was listed in the magazine, ended up buying our first solar panel and wind turbine on the spot, and hooking up a small 12 volt power system for our home that year. It worked really well, we did make some mistakes, but with the knowledge and experience we gained, we were able to get into a larger system a few years later. Now our home generates almost all its own power, and we use the utility company for backup. There is a 1.4 kw solar array on the garage roof, and a 1kw turbine on a metal tower in the field behind the house. We have also installed a batch solar water preheater and have 2 wood stoves for heat. Now our electric bills are around $6 per month.

If your handy at all hooking up electrical devices, you could put together a small system like we did years ago and use it to run some small 12 volt lights and electronics. We still have our little system today, it operates the cabinet lighting in the kitchen, a few radios and phone answering machine, and we have 12 volt outlets in each room. They're handy for stuff like charging your cell phone with a car cord. I would suggest looking at the websites first, and if you're really interested, go for a one year subscription to Home Power. If you subscribe, you can even use their website to look at archived articles from years past. There is even one on our small system, the magazine liked the idea so much they wrote it up. Use their search engine to look for, "Small System First."

Hope you find all this interesting. Take care Bandit, Rudydoo

Charlotte Said:

Solar panel info? i need to know about input and output ?

We Answered:

As stated previously, the solar panels do convert lumens. The output is measured by the wattage in DC, an inverter converts to AC which can then be used by standard electrical devices. There is, generally a 70% efficiency loss during the conversion.