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Old 02-08-21, 06:56 PM   #15
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Originally Posted by jeff5may
I'm just saying that the 25 is what the pros use for sizing utility-scale arrays.
I remain skeptical that they do so.

Originally Posted by jeff5may
The sun doesn't shine at 100% when it's up, and it's down every night.
That is a different topic.

Similar to .. the time a ICE is not running is a different topic , than the efficiency it runs at while it is running .. 20% efficiency for 1 hour or 20% efficiency for 20 hours .. 20% is still 20% .. aka your night time reference.

Similar to .. a 1HP ICE running at 20% efficiency puts out less power than a 100HP ICE also running at 20% efficiency .. but again , 20% is still 20% .. aka your not 100% sun shine reference.

These two points are why average solar hours (at 1 sun) for a given location are researched and published base case figures in the solar industry. A good PV professional would do a site survey to identify how much (if any) specific site conditions would reduce that base case .. used to be calculated by hand .. today this is often done my computer.

Originally Posted by jeff5may
A heat pump isn't a free energy machine.
It isn't free in the absolute sense .. but , I don't care about that .. 'free to me' is what maters to me .. and in that sense .. yes they are 'free to me' energy machines.

If I invest 100 watts of electricity input into a heat pump operating at 3 COP , getting out 300 watts of heat output .. that is 200Watts 'free to me' .. those 'free to me' 200watts did come from somewhere else .. ie taken from the 'cold side' .. but I didn't have to pay for them , I only paid for the 100w input.

Originally Posted by jeff5may
Why do you think that efficiency numbers have constantly been improving over the years?
Like allot of things supply and demand.

Originally Posted by jeff5may
Speaking of heat pumps, here's my heat pump of the week.

Originally Posted by jeff5may View Post
You need to be using a dehumidifier or refrigerator compressor for the HRV for a single family home or smaller dwelling.
No .. 'need' is definitely the wrong word.
I actually do not 'need' to do that.

You are welcome to make any system you like .. I already posted why I will not be using using your heat pump HRV suggestion .. so far you have not addressed those cons of this suggested approach.
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