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80% solar cells

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Someone:

--- Quote from: Kleinstein on August 01, 2019, 05:20:28 am ---Given the relatively low costs for the cells, extra effort in cooling is likely not worth it, unless one has a good use for the low temperature heat. Water pipes and anti-freeze measures can be quite a hassle.
--- End quote ---
Well said, peak junction temperatures of typical panels are 60 degrees or so at full insolation and most of the time well below that so its low grade heat. The gain in efficiency of the PV cells can't cover the costs of a complex cooling system.

thm_w:

--- Quote from: Someone on July 31, 2019, 10:56:38 pm ---
--- Quote from: raptor1956 on July 31, 2019, 08:39:41 pm ---One potential residential co-generation concept would employ solar cells cooled by water and the waste heat used for domestic heating and hot water.  If the cells were 18-20% and you can reclaim waste heat you could up the net efficiency to, perhaps, 25%.  You would need some storage for that but it wouldn't be storage over months, just hours.  Of course, in a residential solar system the solar cells will usually be locked at a fixed angle so the true net would be perhaps 70% of the max or 13ish% + a few percent for heat.  Still, for a typical roof with 100 m^2 of Sun facing roof you'd still be pulling in about 13KW over 4.5-9 hours per days depending on location.  As mentioned before the average daily electric usage is about 30KWHrs so such a system would provide all the home needs and also provide daily commute energy for a couple electric cars.
--- End quote ---
You're out by quite a margin for the energy needed to run multiple cars, average transport use is surprisingly high:
http://www.withouthotair.com/c3/page_29.shtml
that same publication even has an example of a two person house that went full solar:
http://www.withouthotair.com/c6/page_40.shtml
268m2

--- End quote ---

Depends on the person and location, Leaf can do 19.1 kW⋅h/100 km so two people driving 15km commute * 2 ways = 11.5 kWh. 20kWh left over, not quite enough for the average home (30kWh) but enough for an energy efficient household.
The median commute here is 9km. I'm sure in Aus its higher.

Someone:

--- Quote from: thm_w on August 01, 2019, 10:32:24 pm ---
--- Quote from: Someone on July 31, 2019, 10:56:38 pm ---
--- Quote from: raptor1956 on July 31, 2019, 08:39:41 pm ---One potential residential co-generation concept would employ solar cells cooled by water and the waste heat used for domestic heating and hot water.  If the cells were 18-20% and you can reclaim waste heat you could up the net efficiency to, perhaps, 25%.  You would need some storage for that but it wouldn't be storage over months, just hours.  Of course, in a residential solar system the solar cells will usually be locked at a fixed angle so the true net would be perhaps 70% of the max or 13ish% + a few percent for heat.  Still, for a typical roof with 100 m^2 of Sun facing roof you'd still be pulling in about 13KW over 4.5-9 hours per days depending on location.  As mentioned before the average daily electric usage is about 30KWHrs so such a system would provide all the home needs and also provide daily commute energy for a couple electric cars.
--- End quote ---
You're out by quite a margin for the energy needed to run multiple cars, average transport use is surprisingly high:
http://www.withouthotair.com/c3/page_29.shtml
that same publication even has an example of a two person house that went full solar:
http://www.withouthotair.com/c6/page_40.shtml
268m2

--- End quote ---

Depends on the person and location, Leaf can do 19.1 kW⋅h/100 km so two people driving 15km commute * 2 ways = 11.5 kWh. 20kWh left over, not quite enough for the average home (30kWh) but enough for an energy efficient household.
The median commute here is 9km. I'm sure in Aus its higher.

--- End quote ---
Median and average distances are not dissimilar across Australia and Canada. But commuting is only one part of the transport energy use. Household energy use for the houses I've lived in averages under 10kWh a day (2-4 people) so its possible to get right down but thats not matching the actual lifestyles the general population lives. 100m2 of solar is around the usable space on the average house, but doesn't meet the average demands.

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