Solar Thermal is Dead?

[AlanE]

Originally Posted by AC_Hacker

I took 100 (as in 100%) and multiplied it by .99 (as in 99% left in the second year) and multiplied THAT by .99, etc., etc. 50 times and ended up with 60.5 (as in 60.5%) by the 50th iteration.

-AC

To tell you the truth I don't really know because this is from an engineering report I read years ago. All I recall is the 1% per year figure.

I'm not sure if they did a calc and then averaged it or what.

Your method presumes that the material (the 99% that remains) has been unaffected by UV and the heating related expansion-contraction process and that every year only the 1% degrades while the remainder of the panel is immune.

[Xringer]

Originally Posted by AC_Hacker

Don't forget that a PV array on your roof would provide shading and reduce your cooling load.

-AC

The summers are pretty mild here in the NE, compared to many places.
So, the cooling season is pretty short, mostly with cooling only needed during the afternoon hours.

Check out the ave daily low temp (blue line)..... Our peak ave humidity is also pretty low.


Last spring, I did keep the Sanyo running more hours that we needed for
heating or cooling, because having it filtering the air, made the pollen season a LOT easier to cope with.
(Power usage during those weeks was pretty minimal).

Bottom line, PV on the roof wouldn't really save very much on cooling cost in my case.

~~~

Summer temperature measurements of the back-sides of PV panels,
lead me to believe that a large air space under the PV should extend the life of roofing shingles.
(Panels are hotter on their underside).

Maybe it's my imagination, but it feels like the radiated heat (on my face)
when working behind my 800w array, is actually hotter than standing in direct sun light..
Different wavelength?

[strider3700]

Can you just turn the sanyo's fan's on and not use the heating/cooling? We set my furnace fan to on or circulate quite a bit just to get that extra filtering and the UV purification going when we're stuck in here with the windows closed.

[Xringer]

Originally Posted by strider3700

Can you just turn the sanyo's fan's on and not use the heating/cooling? We set my furnace fan to on or circulate quite a bit just to get that extra filtering and the UV purification going when we're stuck in here with the windows closed.

Yes, it has a fan-only mode, but we haven't tried to use it for pollen. Yet.
Since during pollen season it's a little too sunny to have the house buttoned up without picking up some solar gain..
So, the systems will be set to Dehumidify mode at around 23 to 24 C, and not use much very power.

[lucerne96]

I went to a presentation on Solar PV investing in February & learned that solar PV panels should cost around 51 cents per watt by 2014. This is due to the Chinese GOV subsidizing the construction of mega construction facilities which are coming on-line now.

This is what killed Solyndra.

[S-F]

51 cents is still pretty steep for a watt. That would make a 5 Kw array cost almost $26,000 plus installation. I think for me personally the ROI would still be something like 35 years or more. By then we will hopefully be dumping beer cans in our home Mr. Fusion like Doc Brown to power our houses.

[lucerne96]

FYI

The cost of a system right now is about $1.65/ watt.

Compared to say, 2005 when it was ~ $7/ watt, we have come a long way

BTW, your math is off by a decimal place.

Here is some info from FIRST SOLAR

http://optics.org/news/3/5/7

[S-F]

Originally Posted by lucerne96

FYI

BTW, your math is off by a decimal place.

So it is. $2600 is indeed not a bad price.

[lucerne96]

Originally Posted by S-F

So it is. $2600 is indeed not a bad price.

I am currently paying about 10 cents a KWh in Philadelphia suburbs.

It is about double that in Europe. Since most of the counties in Europe must import their energy, they have taken to see real energy independence as a National Security issue. This is one reason that they have put alot effort into very energy efficient buildings & renewable energy development.