Posted by Martin Riddle on June 12, 2010, 9:22 pm
>> Don't forget depending upon the inverter, you'll only need the +
>> buss voltage as most MSW inverters have + and - 165vdc (it's probably
>> closer to 150vdc for a MSW).
> Oops! Would that limit you to half power from the inverter?
> Vaughn
If the inverter has a split bus I don't think it would limit the power.
in normal operation each bus is subjected to alternating 8ms of loading,
I don’t see why one can't constantly load one of the buses, but you
never know.
The AC DELCO inverter I have looks robust enough (multiple parallel
transformers for each bus) to pull this off.
You do need to check regulation, since MSW inverters adjust their AC
output pulse width to maintain 115v.
The bus is the output of just a raw DC-DC converter with no regulation.
But a good thing is there is most likely some form of circuit protection
(Over current) built in, at least one would hope.
Cheers
Posted by EXT on June 22, 2010, 6:23 pm
> This is something that caught my attention. For people looking for a
> viable solar/dc based air conditioning system for their home. Tecumseh is
> making a masterflux branded line of compressors called sierra, for
> 12/24/48 and higher volt operation.
> http://www.masterflux.com/products/sierra/
> They also have complete condensing units built around them.
> http://www.masterflux.com/products/condensingunits/
> High temp is basically the same operating range as AC service. Basically
> an evaporator temp above freezing.
> They have a rated capacity range from 3000 to 6000BTU with a condensing
> temp of 130F. In the real world, with an adequate condenser, condensing
> temps will not be close to 130F. So that is the worst case scenario.
> Actual real world capacities will be closer to 5000 to 10000 BTU with more
> normal 100F condensing temps.
> The only reason you see higher condensing temps on their complete
> condenser line is because they are not really optimized for AC service.
> The condenser coil isn't really large enough to support the higher evap
> temps and higher capacity.
> At a power draw of 374 watts for 3753BTU at 55F evap, and 130F condensing,
> you still push over 10EER which pretty respectable for 130F condensing
> temp.
> If you got a reasonable sized 1 to 1.5 ton condensing unit and put that
> compressor in it, you would not see over 10F above ambient condensing
> temps. That will help capacity and EER for AC service greatly. You would
> have to change the condenser fan over to a 12 DC type. Inside evaporator
> could be anything from a small fan coil, or a wall mount unit.
> Basically the above system with two 200W panels and an AC with a couple of
> golf cart batteries for a buffer and you will have climate control during
> the day time. With big enough GC batts and you could carry cooling into
> the night hours.
> A lot more efficient than running a window shaker on your existing
> inverter/solar installation.
> Granted, 3 to 5kBtu isn't a lot. But in a well insulated house, or part of
> a house, it will make things a lot more comfortable.
> Yes, you would be talking about approximately $4000 for a 5000BTU ac, but
> considering How much a normal central air system cost. Even a mini split
> of that size will cost over $1000. And it doesn't use AC power, so no
> electric bill. 4K bucks for a solar ac doesn't sound that bad.
Since Tecumseh went bankrupt last year, who bought the name and is
manufacturing the equipment under that name, so that they can sound more
legitimate. It certainly isn't the Tecumseh we remember.
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>> buss voltage as most MSW inverters have + and - 165vdc (it's probably
>> closer to 150vdc for a MSW).
> Oops! Would that limit you to half power from the inverter?
> Vaughn