Net cost of going solar

[RobertSmalls]

Originally Posted by NiHaoMike

A friend of mine is working on a hybrid A/C that uses evaporative cooling to cool the condenser of a normal A/C. The prototype gets a SEER rating in the low 30s. It uses distilled water as the refrigerant. Main problem is that the "turbocompressor" (basically a modified turbocharger driven by a switched reluctance motor) is not a mass produced part.

I think I'll try to build my own hybrid A/C in the future, but with a conventional refrigeration loop using ES-22a.

Not to rain on anyone's parade, but my rather ordinary, inexpensive Frigidaire window A/C has a COP of 10.5, or a EER of 36 and probably a SEER around 40. I hope he didn't worsen the COP by trying to evaporatively cool the condenser.

[NiHaoMike]

Originally Posted by RobertSmalls

Not to rain on anyone's parade, but my rather ordinary, inexpensive Frigidaire window A/C has a COP of 10.5, or a EER of 36 and probably a SEER around 40. I hope he didn't worsen the COP by trying to evaporatively cool the condenser.

Where did you get that A/C? Even high end central units are lucky to get 20 SEER. 30-40 SEER is about where geothermal is.

A simple fan can have an effective SEER rating much higher than 40, as can evaporative coolers. But evaporative coolers don't work in all areas and fans might not be enough on the very hot days.
Alternative to Air-con - EcoRenovator

[RobertSmalls]

Originally Posted by NiHaoMike

Where did you get that A/C? Even high end central units are lucky to get 20 SEER. 30-40 SEER is about where geothermal is.

Fantasyland. I'm a metric man living in a mixed-units world! Sorry, it's an EER of 10.5, for a COP of 3.1. I'm now properly impressed by that prototype condenser chiller.

[ShadeTreeMech]

EER i assume is energy efficiency rating, but what is COP?

My burning question is the difference between using evaporative cooling to aid a heat pump type compressor and just using ambient air. if it makes a big enough difference I'd be all over it. Theoretically evaporative cooling will drop the temp by 10-12 degrees F regardless of humidity.

[RobertSmalls]

Coefficient of Performance. It's the amount of heat energy moved from the A/C's cold side to its hot side, divided by the amount of electrical energy required to do it.

An EER is the same figure, but with one of the terms in BTU/hr and the other in Watts, and the units carelessly lopped off before doing the division. EER = COP * 3.413.

[NiHaoMike]

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Looks like there's already a hybrid A/C in production. It appears to be roughly as efficient as the prototype unit my friend is working on. However, it is only available as a rooftop package unit instead of the more common split system. It must also be really difficult to install as it weighs almost as much as a small car! There's also no mention of price.

[TheEnemy]

Last time I crunched the numbers a grid tied (no batteries) system that size cost arround $25,000.

For the area I live in figuring a 20 year life span the power the system would produce would cost $0.20/kwh, or about double what I pay now. Arizona gets a little more sun than we do so that would reduce the costs, and I think Arizona has some extra deductions that we didn't get when I last did my calculations.

Before you get on me about using 20 years for a life span, its not that I don't think the panels can last 20 years, but that the chances of something damaging the system in 20 years is pretty good, be it a freak hail storm, neighbors kids with rocks etc... so I use a conservative 20 years.