Getting my feet wet with a small scale solar project.
Posted: Wed Nov 14, 2012 2:18 pm
Rains the last few summers have resulted in far more cellar moisture than before. I added a dehumidifer and promptly noted increased electrical consumption, quite a bit for what used to be my cheap months. What's a viable alternative? Well I can run a fan to vent the cellar, but how do I control it?
So my first thought is a small solar setup without batteries, run the panel directly to some 12 volt fans. That won't work, voltage from solar panels is AOTP all over the place. Even if a panel has an 18 volt max hooked up to a 24 volt fan (fairly common) the panel may produce less voltage than required to make the fan spin, but sill feed it to the fan which would produce nothng but heat after any length of time.
OK, so step in the charge controller, the device that converts solar cell output into a more useful format. Huge voltage swings can be regulated to produce voltage to charge 12, 24, 36, or 48 volt batteries, meaning they produce a little more than the battery rating itself. You can connect loads to some of them, and it would be inexpensive to have the controller simply power the load in daylight and to not bother with the battery (I don't need or want these fans running after dark.) But it doesn't work that way, charge controllers require batteries.
The only option over a charge controller, which few would be aware of, is the PICO PSU. The lowest cost one has a max of 8 amps on the 12 volt line. This would run my fans, but not much else.
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Stage 2 of my project would be to vent the attic as well. There are some self contained solar attic vents, most commonly the 10 and 20 watt sizes. They are feeble. There are 30 to 50 watt units available, they can be quite costly. None are very long term oriented, very high durability. Other attic fans of interest would be the smallest from Jet Fan US. It comes in under 200 watts but is AC. This could be powered by a small inverter.
There's really no such thing as a solar power inverter, they just can not accomodate huge voltage swings so charge controllers are still be required. Like the cellar fans I really don't need to run them if there's no sunlight, and hence I really don't need the batteries, but the charge controller makes that impossible.
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Having a battery backup, even without the extra cost of an inverter, allows to 12 volt lighting, LED or flourescent, which frankly would not really pay for itself, but would add convenience. This is viable for the rear entrance to my home, since it doesn't have any lighting now and it really should.
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Other passing thoughts:
It's a shame the charge controllers can't do their thing without the batteries. I would not have minded a 1000-1500 watt setup that would create AC only on sunny days to power an air conditioner. Large storage amounts to many batteries, very large gauge cables, added complexity.
I'm not overly impressed with large gridtie systems, the power you sell back to the power company is purchased at a far lower price than what you pay to buy it from them.
Boy there's a lot of crap out there, and by that I mean inverters and other electrical equipment that is not UL approved. I already own equipment that's not UL approved, but all of it is high end audio and built like a brick outhouse. No UL rating becomes an issue if there's a fire in the home caused by non-UL approved equipment. It may give an insurance adjuster a reason not to pay a claim. The super cheap inverters, without any seals of approval, well I wouldn't want to use them anywhere near their maximum rating. And I don't want any inverter that's relying on a 50 cent 12 volt fan for survival.
So my first thought is a small solar setup without batteries, run the panel directly to some 12 volt fans. That won't work, voltage from solar panels is AOTP all over the place. Even if a panel has an 18 volt max hooked up to a 24 volt fan (fairly common) the panel may produce less voltage than required to make the fan spin, but sill feed it to the fan which would produce nothng but heat after any length of time.
OK, so step in the charge controller, the device that converts solar cell output into a more useful format. Huge voltage swings can be regulated to produce voltage to charge 12, 24, 36, or 48 volt batteries, meaning they produce a little more than the battery rating itself. You can connect loads to some of them, and it would be inexpensive to have the controller simply power the load in daylight and to not bother with the battery (I don't need or want these fans running after dark.) But it doesn't work that way, charge controllers require batteries.
The only option over a charge controller, which few would be aware of, is the PICO PSU. The lowest cost one has a max of 8 amps on the 12 volt line. This would run my fans, but not much else.
----------------------------------
Stage 2 of my project would be to vent the attic as well. There are some self contained solar attic vents, most commonly the 10 and 20 watt sizes. They are feeble. There are 30 to 50 watt units available, they can be quite costly. None are very long term oriented, very high durability. Other attic fans of interest would be the smallest from Jet Fan US. It comes in under 200 watts but is AC. This could be powered by a small inverter.
There's really no such thing as a solar power inverter, they just can not accomodate huge voltage swings so charge controllers are still be required. Like the cellar fans I really don't need to run them if there's no sunlight, and hence I really don't need the batteries, but the charge controller makes that impossible.
-----------------------------------
Having a battery backup, even without the extra cost of an inverter, allows to 12 volt lighting, LED or flourescent, which frankly would not really pay for itself, but would add convenience. This is viable for the rear entrance to my home, since it doesn't have any lighting now and it really should.
-----------------------------------
Other passing thoughts:
It's a shame the charge controllers can't do their thing without the batteries. I would not have minded a 1000-1500 watt setup that would create AC only on sunny days to power an air conditioner. Large storage amounts to many batteries, very large gauge cables, added complexity.
I'm not overly impressed with large gridtie systems, the power you sell back to the power company is purchased at a far lower price than what you pay to buy it from them.
Boy there's a lot of crap out there, and by that I mean inverters and other electrical equipment that is not UL approved. I already own equipment that's not UL approved, but all of it is high end audio and built like a brick outhouse. No UL rating becomes an issue if there's a fire in the home caused by non-UL approved equipment. It may give an insurance adjuster a reason not to pay a claim. The super cheap inverters, without any seals of approval, well I wouldn't want to use them anywhere near their maximum rating. And I don't want any inverter that's relying on a 50 cent 12 volt fan for survival.