Brad Ideas - Solar Powered PC - Comments

No solar power system can

brad — Fri, 21 Dec 2007 16:27:36 -0800

No solar power system can recover its cost compared to grid power, as yet, except in very specialized applications. You buy one because you want to spend more than grid power to be greener. At least compared to typical grid power. In California, with tiered grid power costing 30 cents/kwh, they can pay for themselves. With rebates you can compete with grid power. Without it's about 20 cents/kwh for solar.

Larger systems all need a charge controller before connecting to batteries. I don't have enough experience to know if it's a problem if you have this connected to a battery that is on another charger/controller. Trickle charge panels deliver so little power I presume there is not much harm that can come from direct connection of their power, that's my guess.

Cheap Solar Power

Seb — Fri, 21 Dec 2007 12:03:29 -0800

Is there any budget solar power solutions, say $400, which quickly recover its cost? I keep looking at solar power, I can afford more, but my main concern is that I'm likely to move house within 18 months, do you have any suggestions?

UPS & Solar Power

Seb — Fri, 21 Dec 2007 11:56:35 -0800

I have a couple of PCs running from a small UPS (which are switched on most of the day), just wondering if it would it actually reduce the load from the mains if I connected my solar power trickle charger directly to the battery. From what I understand, the power is constantly delivered to the PCs from the mains via the battery. If it something like that works, then thinking of buying a larger panel to connect to it.

Bad idea

brad — Thu, 20 Dec 2007 11:08:03 -0800

I don't know about the safety, but it's not important because this is a poor idea, and quite ungreen. For solar panels to be green, you must use their power. Trickle chargers which spend 99% of their time throwing away their power into already charged batteries are a net energy loss -- it takes a lot of power to make the solar panel at the plant. They only make sense in places that other power is not available, such as a car sitting unused for a month. In a UPS, there is plenty of power.

Or do you have another purpose in mind, ie. doing this on a UPS that is not plugged into the wall, and does not have a load on it, as a way to recharge the battery, very slowly, for short bursts of usage later?

Solar power

Seb — Thu, 20 Dec 2007 05:56:10 -0800

I'm just wondering, is it possible to buy a bulk standard desktop UPS, and connect a standard car solar power panel (trickle chargers) directly to the battery installed in it? Or would this harm the UPS?

Robert Nixon — Fri, 08 Oct 2004 18:33:48 -0700

>A solar panel takes 4 years just to
>give back the energy it took to build it

Some types of photovoltaics take less than a year to reach net energy gain, and will produce 20, perhaps 30 times their embodied energy over their lifetimes. Here are a couple of links:

http://www.apec-vc.or.jp/solar/outline/outlne09.htm
http://www.ecotopia.com/apollo2/pvpayback.htm

Gene Carman — Mon, 20 Sep 2004 09:00:48 -0700

Actually there are a whole host of folks that rely on good solar power... long distance sailors... here is an example: http://www.svmirador.net/SolarPanels.htm

In this particular case the panels supplied enough power while in the Sea of Cortez to run refridgeration, run a water maker, power SSB radio and computer. Frankly sailors can and do live off the grid.

I understand that newer more efficient panels are on the way.

I think the real key to harnessing solar power is to not depend on one single form... the combination of passive solar heating (with passive mass storage), photovoltaics, and even focused arrays for cooking could be the solution for future energy needs.

Lee Ackerson — Wed, 15 Sep 2004 01:05:13 -0700

Re: Solar. Some states allow grid-tied solar systems which put energy into the grid at peak load times and you can select a rate plan which pays you more for the power you put in during the day than the power you draw out at night. So, you would want to scale your solar output to break even and using it wisely could do that.

Also, we had a guest lecturer here a couple of weeks ago talking about solar and he stated that the break-even point between the energy used to make the panel and the energy generated was about 3 1/2 years, but about 2 years of the energy to build the panel( I believe those were the correct figures) was consumed in making the aluminum frame!

Lee

Solar Powered PC

brad — Mon, 13 Sep 2004 11:53:01 -0700

We all would love solar power to work better, but it's hard to have it make economic sense yet, at least if you're near the grid. A solar panel takes 4 years just to give back the energy it took to build it, and it never pays back the money put in if you compare it to putting the money into the stock market. And that's with full utilization. If you use panels and batteries, any time your batteries are near full the power is being discarded, and you also have to replace your batteries every so often and dispose of the old lead-filled ones. Yuk. A grid-tie can use all the power of a panel but that's an expensive, whole-house thing.

But here's a start -- a solar-using PC power supply. My PCs, like many folks, are on all day, including the peak-demand heat of the day. Desktops draw anywhere from 50 to 200 watts, IIRC.

So make a PC power supply that has 3 external connections. One for the wall plug, of course. And two optional ones, one for a 12v solar panel and one for a battery. Then sell it with a 50w or 100w solar panel -- most importantly, the panel should not generate more power than the PC uses.

Because of that, during the bright part of the day, the panel will be providing most, or just barely all, of the power for the PC. The wall plug will provide the rest. At night, the wall plug would provide all the power. It's a grid-tie but it doesn't feed power back to the grid, it just reduces demand on it. The 100w panel takes 100w off the grid load during the peak demand times. And we use every watt the panel generates, we never throw any away.