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bennelson · 02-12-10, 09:58 AM

I already have a 48V UPS system, which I got from a computer salvage friend.

A UPS combines a charger, batteries, inverter, and automatic switch, all in one unit.

If I was able to supply 120V AC to the UPS when the sun is shining, it would take care of charging the batteries, and automatically make AC from the batteries when it was no longer getting power.

Grid-tie inverters are designed to directly handle high-voltage panels (with inputs up to 500 or 600 volts!) but are costly. The most basic high voltage one I have found so far is a SunnyBoy SB700, which is just over $1000. Even then, that one has a "safety-feature" of turning off when it senses that it isn't connected to the grid. So, running AC to my UPS might not make sense/be cost effective.

If I try to charge batteries directly, I need a solar charge controller. However, most of them are designed for 12, 24, or 48v. A single panel of mine makes MORE than 48V!
Some charge controllers feature MPPT - which can lower the voltage of a panel by converting some of it to amperage, which is really what the batteries care about anyways. Of course, this is fancy technology, which costs money. The Outback Flexmax features MPPT, can can handle a max incoming voltage of 150v. That means I would need to put all the panels in parallel, because even two panels in series could potentially add up to more than 150v. This would mean more wiring, a big combiner box, etc, etc. One of those charge controllers runs about $600.

If I did get a MPPT charge controller - that would charge the batteries directly. I would use the UPS as the inverter, and my garage could go off-grid - yeah!

02-12-10, 09:58 AM	#12
bennelson Home-Wrecker Join Date: Sep 2008 Location: SE Wisconsin Posts: 546 Thanks: 3 Thanked 165 Times in 96 Posts	I already have a 48V UPS system, which I got from a computer salvage friend. A UPS combines a charger, batteries, inverter, and automatic switch, all in one unit. If I was able to supply 120V AC to the UPS when the sun is shining, it would take care of charging the batteries, and automatically make AC from the batteries when it was no longer getting power. Grid-tie inverters are designed to directly handle high-voltage panels (with inputs up to 500 or 600 volts!) but are costly. The most basic high voltage one I have found so far is a SunnyBoy SB700, which is just over $1000. Even then, that one has a "safety-feature" of turning off when it senses that it isn't connected to the grid. So, running AC to my UPS might not make sense/be cost effective. If I try to charge batteries directly, I need a solar charge controller. However, most of them are designed for 12, 24, or 48v. A single panel of mine makes MORE than 48V! Some charge controllers feature MPPT - which can lower the voltage of a panel by converting some of it to amperage, which is really what the batteries care about anyways. Of course, this is fancy technology, which costs money. The Outback Flexmax features MPPT, can can handle a max incoming voltage of 150v. That means I would need to put all the panels in parallel, because even two panels in series could potentially add up to more than 150v. This would mean more wiring, a big combiner box, etc, etc. One of those charge controllers runs about $600. If I did get a MPPT charge controller - that would charge the batteries directly. I would use the UPS as the inverter, and my garage could go off-grid - yeah! __________________ To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.