Author Topic: Load Control (sort of)  (Read 1151 times)

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(unknown)

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Load Control (sort of)
« on: May 24, 2008, 04:21:05 PM »
Why isn't there (or where could I find) a device that would manage two separate power sources for one appliance?


For instance, if a person wanted to run a something, like a refrigerator, on alternative energy source that may not be able to provide all of the power all of the time.


Thanks and I'm sorry if this is a really stupid question!

« Last Edit: May 24, 2008, 04:21:05 PM by (unknown) »

rippersoftware

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Re: Load Control (sort of)
« Reply #1 on: May 24, 2008, 10:33:00 AM »
This guy in England has made a circuit that senses the battery power is falling and reconnects the main juice to the laptop (his server).  I guess this would be a sort of Low Voltage Disconnect (LVD).


http://www.fieldlines.com/story/2007/6/28/17204/5642


Has other applications as well.

« Last Edit: May 24, 2008, 10:33:00 AM by (unknown) »

DamonHD

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Re: Load Control (sort of)
« Reply #2 on: May 24, 2008, 12:46:22 PM »
Hi,


You might want to look at later, better, and better-drawn implementations!


http://www.earth.org.uk/low-voltage-drop-out-circuit-design.html


Of course, you'd need to scale things up, drive a solid-state-relay or whatever.


Rgds


Damon

« Last Edit: May 24, 2008, 12:46:22 PM by (unknown) »
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dnix71

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Re: Load Control (sort of)
« Reply #3 on: May 24, 2008, 06:23:45 PM »
You could also get a used computer server UPS. Something large enough to start and run the appliance. Server UPS's are made to run indefinitely from batteries. If you put an industrial battery charger on the batteries and connect you solar or wind to the same batteries, then the battery charger running from the mains will make up the difference, and your batteries will stay fully charged, which increases their life.
« Last Edit: May 24, 2008, 06:23:45 PM by (unknown) »

jonas302

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Re: Load Control (sort of)
« Reply #4 on: May 24, 2008, 09:10:19 PM »
I guess it depends on your solar source if its small wouldn't the inefficiencys of a charger and a ups stack up to be a net increase in the power bill?
« Last Edit: May 24, 2008, 09:10:19 PM by (unknown) »

dnix71

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Re: Load Control (sort of)
« Reply #5 on: May 25, 2008, 02:35:06 PM »
For a small array, it wouldn't make sense. But grid tie inverters are quite expensive.

Thats what is usually used. I have a coworker with a 5kw solar pv array. She has all of it tied to batteries and a grid tie inverter. The system cost $55k before the state $20k rebate for solar.


The grid tie inverter takes power from the grid only if necessary and keeps the batteries topped off, and will run for days on battery power alone even if it's overcast and raining.

« Last Edit: May 25, 2008, 02:35:06 PM by (unknown) »