[amsat-bb] Waiting for Solar Panel Efficiency (Ha!) rebuttal

Robert Bruninga bruninga at usna.edu
Fri Jan 1 16:21:27 UTC 2016

> If the project is not operating by now, it'll cost 30% more after

No. The 30% federal tax incentive was to end by the end of 2016, not the
beginning.  AND does'nt matter anyway, since the do-nothing congress
actually included an extenaion in the spending bill.

> Putting solar on an asphalt roof ... is a bad idea.  Not a place to screw

Use a reputable contractor with guarantee.  They know how to do it right.

> 42 panels 50 lbs per (for 11 kW system)...
> Remember statics and dynamics??
> ... bracing rafters in a crawlspace is a mug's game.
> In Florida in summer? Fatal.

50 lbs per panel over 18 sqft is only a load of 2.8  lbs per square foot
and is insignificant compared to the required building code roof design
figure of typically 30 psf.  (Though in Florida the snow load is considered
0).  The good news elsewhere is that solar panels melt snow far faster than
a normal roof, so there is no multiday buildup and icing load...

> Today as of 3pm EDT the system produced  23 kWh.
> Best day so far was 100% FL sunshine and a COLD day: 82 kWh.

Congratulations, sounds like you did it anyway...

> HF RFI? Undetectable.

Thanks, that is great news!

> I got the last (3) 3.8kW transformer based inverters in stock.
> SMA makes nice gear. Cadwelds, IMC 3/4" conduit.

I was totally shocked when I ordered an SMA inverter to add to my other
three XANTREX ones which only weighted 25 lbs.  The SMA was so heavy I had
to invite my son to dinner just to get help getting it from the porch to
inside the house!  Then had to feed him again a week later to help lift it
into place.  I think it is over 100 lbs? And compared to the XANTREX, there
were may nitpicks I did not like about the SMA at all.

But then of course, XANTREX doesn't make grid-tie inverters any more and
SMA does seem to have very good reviews.

On Thu, Dec 31, 2015 at 12:25 PM, Bob <WB4SON at gmail.com> wrote:

> > Sort of off the AMSAT topic, but the most recent estimate is that about
> 20
> > gigawatts of solar will be added in 2016 -- almost doubling the total
> > installed capacity of US solar power.  This is being primarily driven by
> > residential installations.  Utility-scale installations are actually down
> > 5%.
> >
> > One thing that was keeping mass market efficiency down was a glut of
> > production capability that existed through 2014.  Manufactures were not
> > keen on investing in new processes at the same time they were going out
> of
> > business or consolidating.  That glut has been drying up, prompting Elon
> > Musk's to build a $1 billion dollar factory in Buffalo NY which will
> > produce 1 GW of panels annually by the end of 2016.  Those panels are
> > expected to be 22.1% efficient.  That's a pretty impressive gain in
> > efficiency.
> >
> > Often times market conditions, not technology, dictates what reaches the
> > mass market, and that has most certainly been the case in the solar
> > industry.  That 50% increase in panel efficiency doesn't necessarily mean
> > that the cost per watt will be reduced in the short term -- those panels
> > may simply sell for 50% more.
> >
> > 73, Bob, WB4SON
> >
> > On Thu, Dec 31, 2015 at 6:07 AM, Nick Pugh wrote:
> >
> >> Good point Bob but include the real estate cost  in to the equation and
> >> they improve.
> >> nick
> >>
> >> -----Original Message-----
> >> From: AMSAT-BB [On Behalf Of Robert Bruninga
> >> Sent: Wednesday, December 30, 2015 11:06 AM
> >> To: amsat-bb at amsat.org
> >> Subject: [amsat-bb] Waiting for Solar Panel Efficiency (Ha!)
> >>
> >> Compare the cost and efficiency of solar panels for cubesats and for
> your
> >> house:
> >>
> >> http://aprs.org/Energy/solar/efficiency-comparison-cost.png
> >>

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