Hawaii - way out font. In a bad way.

Greentech media has a pretty good intro to the current state of things in the USA's most built out PV market: Hawaii.

story here

Among the things that stand out are

1) Many circuits on Oahu that are 120% of Daytime Minimum Load.  Too much of a good thing?
2) Discussion of the end of Net Metering. (duh!)

Some more up to date comparisons...

I'm off to work on Rev 2 of the design but it seems appropriate to layout why it is worth the bother.

Here are some comparisons to two good examples to give context :

Kyocera 325W Polycrystalline Solar Panel KD325GX-LPB
and (the awesome)
SunPower SPR-X20-445-COM (445 watts!)

Fortunately they are both 2.19 square meters each so watts per square meter STC can be derived but a better gauge is PTC (avail here) which mostly accommodates the Temperature Coefficient in a more real world manner:

Kyocera's goes down to 290.4 for the panel and so 132.6 per square meter
Sunpower goes down to 412.7 for the panel and so 188.45 per square meter
vs
Hybrid V1 is 23 watts per tube and 128 per square meter

We could imagine those panels reformed as magic edge-less strips as long and wide as our tubes and get
23.9 watts per strip from the Kyocera
33.9 watts per strip from the Sunpower
vs
23.0 watts from our tube (setting aside the thermal for the moment) 

How to layout the hybrid value? Here is an attempt at a tote board, normalized to per square meter



Top scored cells BOLD

OR if you'd rather:
1 panel of 2.19 square meters (1.66m X 1.32 m = 2.19 m^2) ≈ 12 Hybrid Rev 1 tubes ( .18 m square each X 12 tubes  = 2.16m^2 of area)

More on Hybrid version 1:
The Hybrid collector's first design iteration was analyzed in part by BRO (http://www.bro.com/) This design revealed some shortcomings that I've attacked in the version two but the analysis of version 1 can serve as a "floor" for evaluation. The figures were good enough to keep going on... Some of the shortcomings of the rev one design and their easy resolution I'll cover later. But for now Rev 1 is the best understood as far as throughput. I think 20% of the losses in Version 1 can be clawed back but all of this post is about Version 1.

For a square meter of tubular collector 320 watts of visible light hit the PV cells in clear light. That light arrives on 10X10mm cells at 46,700 W/m^2 (46.7 Suns.) The 320 watts would hit 98 10mmX10mm concentrator cells in that design. and the cells should be able to operate at @66C or below. They could be expected to run at 40% (due to the rich diet and the high concentration/low temp.) that 320W*.40= 128w =12.8% efficient (started vs the 1000 Wm^2 total light) on the PV side in realistic atmospheric conditions. There are troubles with that 12.8% number but they cut both ways. The fraction of incident light captured in the heat components is about the same (340W) but the conversion is much more efficient ~80% at 160C output temp. So 340W*.80=272 or 27% on the thermal side for a net 39.8%

Some of the columns need explication:
Relative Performance on a Heat Load:
Cogenera (in a white paper) sees the _heat value_ as 25% of electric value in a Watt to Watt comparison when that heat is delivered at Domestic Hot Water Temps. Sounds fair. So 128+(272*.25)=196. I weighted them all at the Sunpower as 1 (the conversion losses in electric resistance heat being very low, these correspond to the Gross Efficiency number.)

Cooling Power in Watts:
Cogenra shows the way again in a paper "Cooling with Cogen" they find the value of high temp heat used in chilling service to be higher than plain old thermal DHW service due to the COP (coefficient of power) in double effect chillers. Thus we get the "Cooling power in Watts" comparison. In most cases I imagine those "Cooling Watts" would be Watts not used ("negawatts" generated at peak rates) and potentially freeing up watts from the electrical side to sell at those peak rates or to otherwise address demand charge problems. All subject to the particular installation conditions and metering contracts of course.

String vs Micro-inverters... I found a pretty good comparison.

Aussie Made Solar has a pretty good pro/con size-up of the micro-inverters (usually one per panel) and traditional string inverters (just one for the whole shebang.)

The biggest difference to me is the lifespan. The micro-inverters should last as long as the panels (25 years) while the string inverters are considered a success if they last 20% of that. But that is just one of the issues - they do a good job of thinking out several issues including the crew size.  Take a look and let me know what you think.

Oh, uparmoring the conduits for the highvoltage DC runs is also an expense that does not jump out until, well... it jumps out.

Securitizing Solar Backed Assets. Nice to see the rates are so reasonable

SolarCity announced some good news on their efforts to rap up parts of their business, sell them off as Securities and roll the money forward.

Street Insider has the story. They frame it as good news for SunPower and I suppose it is. Beating the rate you expected by 2% over a 13 year period is a pretty strong indication that your credit is good. So Congrats to SolarCity. I'm going to let them off the hook on predicting because it is a new market and until a match is found, it is just guess-work...

I'm foggy on how those instruments wrap up at the end. Who owns what. The security holders have their money back with the interest. I guess the contract for Power Purchase is still in play so the income still flows to SolarCity and there is no more debt to service... Maybe they can do it again?

Meyer Berger - Welcome to the Thunder Dome!

check 'em out:

A new flat panel hybrid from the Swiss company Meyer Berger.

One of the selling points is that they are made in Thune (Switzerland.)  In one of the press releases they are promoting its use as a geothermal probe recharge method. Smart. That would mean lower temps which means more electric production but the pumping cost are non trivial: 50 to 100 liters per hour (per panel) to keep it down to 80c. Obviously lower temps would require more pumping. The fittings are 10 mm diameter.

They reference vacuum technology but I do not see where it is folded into the design looking at the PDF cited above. It is patented but the patent may not be held by them? I could not find it.

Some more digging is in order I suppose.

Back in 2011 I should have listened to my own advice and shorted a bunch of CPV

In an email (I wrote) I just saw again today, I read this:

 I wish I could find some time and some speculative money to short them as a group. Not just based on your reservations but my own. Such huge engineering inputs and robust gear waiting around for Spectrolab to get the triple junctions price down. And all that front-side risk just to hand themselves over to utility companies (who have access to cheap aperture and have to mark it up for retail) to get roughed up. And the redundancy of the work from company to company. They all have their own proprietary but indistinguishable stuff it seems. I have a licensing exit as my goal but most of these VC types want to build a soup-to-nuts company. So I considered (as an exercise) just suggesting we develop my product while staying as virtual as possible and then buy a concentrator company for pennies on the dollar when we need a manufacturing arm. While we work on our value - we'd let them grow wild (and let the herd thin while we got our act together.) Finally, we'd harvest the best bargain when and if we needed it.

Grim, I know, but there you have it.

SolFocus spins out...

I was reading one of their reports on progress to the NREL. Serious development on many fronts. But being beholding to fickle investor pools and on what I call the "wrong side of the meter" finally caught up with this pretty classy outfit.

more over at PVMagazine

Here is the report I was reading. I wonder what IP they have and for what price?