Thursday, December 13, 2007

New solar panels are up!

Hey, Chrusty Churkey!  Here's a nice long dense one for ya!  :-)
(For others- do be aware there will NOT be a test after you finish reading- feel free to skim over some of the technical bits; and you'll find pithy parts here and there, and at the bottom...)

As regulars here will remember, in October we had the delightful addition to our work of having our greenhouse solar power array wiped out by a direct lightning strike.

We did, finally, get the panels replaced, and up and operating.  That was a whole bunch of work- illustrating a number of points regarding attempts to move towards a greener lifestyle.

The solar panels WERE covered by our business insurance.  Mostly.  They're expensive, you know- and critical to the business, since they provide the main power for the greenhouse; so they were specifically listed on the insurance policy (unlike our stolen farm truck- not listed; worth $500 or so, and a minor piece of equipment- that was NOT covered; though our stolen chain saw; not listed, but worth $800 or so- WAS... go figure.)

But.  Insurance has become a game where most insurers spend most of their effort figuring out how to NOT pay you anything for your losses.  They sell you the policy smiling and saying "we're here to help you through bad times!" and when the hurricane hits, it's "no, no, see the fine print here?  Says if the storm hits on a Thursday, we don't owe you anything!  Ha!  Gotcha!"  

In fact my business insurance company is WAY better than most- they specialize in insuring nursery/greenhouses, and that whole world is small, and idiosyncratic in spades; so they have to be somewhat accommodating just to survive.  

The coverage on the panels though was a little too specific to be useful, causing an extra 4-6 days of discussions before we could agree on how to proceed.  The policy read "6 solar panels, max coverage $300 apiece; prorated for age; maximum liability #1800.00."

What I actually lost was 6 Siemens single-crystal panels, rated 48 watts apiece, installed in 1992.  All 6 were damaged by the lightning strike- which was just as well, since trying to find panels to hook up and replace half of the array would have been impossible.

No, that's not me, that's Jerry, who came all the way from NY to help out.  These are the panels AFTER the strike, incidentally - they look fine from this distance - but they don't work; blocking diodes melted, and some of the surface wiring between individual cells was vaporized.  Took me several days before I noticed my battery bank was not getting charged.

Nobody makes 48 watt panels today (that I could find) - and the standards for the precise inner workings of the panels have changed...

In fact EVERYTHING about solar panels has changed since I bought my first ones- in 1982, I think (the cost- about $15/peak watt.)  The only option then was single crystal- and a "nominal" 12V panel put out 16.something V max under load; 19V open circuit.  If YOU are the one putting the system together, yeah, you have to know ALL those numbers; they make all the difference in whether the array is going to work or not.

Also, when I first bought panels, there were approximately 3 companies doing business- and the internet did not exist.  Decisions were pretty simple.  

Not so today.  There are about 25 major companies selling panels over the internet- from about 15 different major manufacturers.  And there are minor ones, too.

The good news is- the internet really does let you compare stuff very well.

The bad news is; it still takes hours- and it's still confusing/confused after you've done your darnedest to untangle it.  

Let's just start with the hardware.

There are now single-crystal; poly-crystalline, amorphous, wire-pulled crystal, and hybrid solar panels to choose from.  At least.  Are there differences?  Duh.  Do they matter?  Hey, just read their advertising!  

Is there a good disinterested source that compares the types, based on initial cost, length of service, rate of power loss... fragility... track records...?     Not that I could find.   Actually I couldn't find even a bad, self-interested source with broad comparisons.  Even digging down into the scientific reports and engineering journals didn't help.  Half the technical info is on cells not available to the public- Gallium Arsenide, instead of silicon- and even more exotic stuff.  Wildly expensive, and not going to be available for decades, if ever, to you and me.

Just sorting out, with some level of certainty, the differences between the stuff that IS available took days.

So, here's what I learned, and what I think.  No real guarantees I'm right, though.

The original solar cells were made in the 50's - out of single cell crystals.  (They're still working, incidentally, though at a reduced output.  You own any other gizmo that's 50 years old and still works all day every day?)  

When people got interested in trying to get the cost of solar cells down, they came up with "poly-crystalline" cells.  They were supposed to be cheaper to make (though I don't see any real price differences today).  But- originally, they didn't put out as much power as single-crystal cells; and they didn't last as long.  Today, their specs claim they DO make as much power- and the 20 year/80% output guarantees are very similar.  But.  When you dig down- it seems that the RATE of power loss is still higher for both poly-crystalline and amorphous cells; single crystal cells lose power at something like 1% a year for the first 25 years; the others may lose power at 2-4% a year for the first several years; then slow down the rate of loss.

Amorphous cells rarely last longer than 10 years before needing to be replaced- they're just not as durable.  Cheaper, flexible, lighter weight, but not going to last- barring lightning (or earthquakes, tornadoes, or what-have-you), a good silicon array can be expected to function adequately for - FORTY YEARS.  

Eventually I decided I did want to go with the old single-crystal cell type.  Mostly because they've got the track record.  Some of the newer types are a little more efficient- but they haven't been around for even 20 years, so we don't exactly know how they'll be doing down the road.  Ok.  Now- which ones?  Made by whom?

Here some of the panel sellers ARE useful- the best ones list good, uniform technical specs for each panel- with the manufacturer's spec sheet available as a downloadable PDF.  Great- still very time consuming, and you have to be conversant in the language; and able to sort out stuff like:

Performance under standard test conditions (STC)
Peak Power (Pmax): 175 watts
Maximum power point voltage (Vmpp): 35.7 volts
Maximum power point current (Impp): 4.9 amps
Open Circuit Voltage (Voc): 44.4 volts
Short Circuit Current (Isc): 5.4 amps

Performance at 800w/sq m, NOCT, AM1.5
Peak Power (Pmax): 131 watts
Maximum power point voltage (Vmpp): 33.1 volts
Maximum power point current (Impp): 4.0 amps
Open Circuit Voltage (Voc): 41.1 volts
Short Circuit Current (Isc): 4.4 amps

Minor reduction in efficiency under partial load conditions at 25C at 200 W/sq m, 95% (+/- 3%) of the STC efficiency (1000 W/sq m) is achieved

And, what does that all mean?  Basic translation: "these panels claim to be 175 watt output, but "Standard Test Conditions" are unrealistic; slightly more realistic ones suggest 131 watts is a better average guess; and if it's a little cloudy, subtract more.  These are "nominal" 24VDC panels- which is why they're putting out 35.7V under good conditions, of course- so your 24V batteries actually get charged."

Getting a headache yet?  I sure was, around day 4 of trying to sort this stuff out.


Slight aside #1: if you're thinking of getting solar panels- or a wind generator- do you really have to know all this technical stuff?

Answer: It's very much like getting your car fixed.  You either have to be able to do it yourself; or you need to be able to TRUST your mechanic.

There are plenty of mechanics who will rip you off if they CAN.  "Hey, your infrahydraulic-frammulator is totally clogged!  Dangerous to drive with it that way!  I can put in a new one for only $320!"

Unless you know SOMETHING about it all; you're at risk of being ripped off, but good.  And the more you know; the better.  Not to mention that even good honest mechanics DO sometimes make boo-boos- and it helps if you're paying attention- knowledgeably. 

The good news again- is the internet.  You CAN educate yourself enormously faster, and better, than you could 15 years ago.  But you still need to go into the process with your brain turned on; and be aware that there are thieves and liars on the internet, too.  Surprise.


So - back to my installation- here is what I wound up with: 

Two panels; instead of 6.  And they're 24VDC instead of 12 (greenhouse battery system is 24V.)  Those numbers above are for these panels; nominal 175 watts.

Basically, as more folks are installing solar arrays, the available panels have been getting bigger- and cheaper. Some economies of scale do seem to be kicking in. These panels were advertised at one site as $4.60/watt - which is CHEAP. Buying 50 watt panels to replace my 288 watt array would have cost me over $6/watt, best I could find. Some good incentive there for me to go just a bit larger; I can always use the extra power.  Now- which panels, exactly?

The basic specs on a lot of panels have changed since I last bought some, 10 years ago.  They all operate at slightly higher voltage; and they ALL come with built-in blocking diodes; something my first ones didn't have.  All that is good- part of the learning process I'd helped pay for, by buying the early stuff.  

And yes, I intended to support a growing, immature industry, by paying outrageously high prices for electricity- when friends and advisors kept pointing out "that's not even close to a competitive price for power, you know."  I knew.  We need to support green processes with our own dollars- they'll die on the vine, otherwise.

When solar panels were experimental, the engineers naturally  - put them out in the sun, right?  And measured their performance.  Unfortunately, residences and small businesses have some other factors in their reality - they're called "neighbors", "utility lines", and "trees".  All of which make "shade".  It turned out that having just ONE CELL shaded on the old panels could make the whole array quit producing power.  The voltage would drop on one panel- so the other panels would now push power- into that low panel, not the batteries.  The blocking diodes prevent that from happening; so one shaded cell doesn't mean you lose the output of the whole array; just that one panel.  And the higher over-all voltage also helps - better performance when it's a little cloudy, for example.  Quite significant in terms of power delivered to the batteries, over the years, in the real world.  Ok; having sorted THAT out (took one day, I think); I started looking just for bigger single-crystal panels, with an open circuit voltage around 44V...

Picking a manufacturer was an odyssey, too. In case you haven't noticed, the big petrochemical companies have been buying up the solar cell manufacturers. Eww.

The first panels I bought were Solarex.  They were among the first to sell to consumers; based in Maryland, I think- big plans for building a "solar breeder" plant; where all the power to make their cells would come from... solar cells.  BP (British Petroleum) bought them, quite a few years ago now- so BP can print tons of ads about how wonderful BP is, for doing all this advanced research on solar power.

Same thing happened to the Siemens solar division- which made the panels the lightning hit.  They were bought out by Shell Oil.  Double Eww.  I will run out of gas, and walk, before I buy gasoline from Shell.  Long story.

Then I ran into very similar panels made by Conergy- which, it turns out, is a German company.  Cheap, too.  Except.  As it turns out.  When you dig into the technical sheet - THESE particular German panels, imported into New Jersey, are actually made in China.  Which you can really only tell IF you can decipher their product code- they don't exactly brag about it.

Now- I'm the opposite of a China-basher.  I love the place; love the people, and I think as a country they have huge potential, if they can just avoid making all the mistakes we already have.  Sure, they have some corrupt politicians and greedy businessmen - uh - SO DO WE, in case you haven't noticed.  They also have huge numbers of very good people, including some politicians and businessmen, doing their darnedest to make China; and the world, "work".

But it IS on the other side of the planet- and the energy required to ship them just doesn't make environmental sense, as we know.  I'd rather pay more money for panels made somewhere closer.  Back to the drawing board.

There was another panel; made by a company I'd never heard of- "SolarWorld".  Kind of a cheesy name; sounds like they hired a consultant to choose it...

Digging to find out who they are- turns out, it's a German company, with what looks like a good track record- and - guess what!  These panels are being made in the California factory that they just bought- from Shell!  Who bought it from Siemens.  Round we go.

I liked the quality of the panels I'd had - these are probably made by the exact same PEOPLE - and Shell is now out of the picture.  The engineering and manufacturing is critical on anything that SHOULD last for 40 years.  These guys seem to know how.  Ok, we have a winner.

I didn't buy the panels where they were cheapest.  A) they didn't answer my emails; B) their website was a little slick and short on information; C) they shipped from the east coast; and these panels are made in California.  I bought my two panels (a tiny order) from a company that ships from California; and they answered my emails, and even called on the phone to see things were going ok with the order.

The panels arrived on a semi (too big for UPS) - like 2 days after I made the order.  Took several more days to get them installed; the old mount really could not accommodate the much taller panels; we managed to modify the old mount with some new steel; lots of sawing and drilling.  Used an old "post drill" hand powered drill press to make most of the new holes in steel.  Then took most of another day to get the panels bolted on, and wired (VERY CAREFULLY).  And we added MORE lightning protection; another ground rod, just for the panels; heavy ground wireS.  With any luck; it should be good for 40 years.
That's most of the story on replacing the panels.  A huge part of my reason for detailing it here is to highlight the real difficulties of sorting out "what's green; what's greener; what's true; what's false; what's real; what's fake..." out here in the real world.  

That's a topic that's come up several times in all the blog conversations I check into; for example No Impact Dude; Chuncky Chincken, and Green as a Whistle.  And others.

Just the topic of "exactly how useful/green are Compact Fluorescent Lightbulbs" turns out to be complex enough to keep people writing about it, including me.

At the moment there's a serious shortage of authoritative and trustworthy voices on green consumer practices, and a worse shortage regarding particular practices.  The US Federal Govt. occasionally puts out some good comparative data- sometimes very extensive- BUT; you really have to dig for it, often it's in a weird incomprehensible form, and sometimes- it's biased by politics.

The only way to get this problem fixed: 

1) Get everybody to understand that you have to take ALL "this is green" statements with a grain of salt- and do some homework of your own to see if you can believe it.  And always will.

2) SOMEBODY (not me, I'm really busy) needs to found a green version of Consumers Union; the publishers of Consumer Reports.  They're non-profit; never accept advertising from ANYONE; forbid any maker to use their name to recommend any product (and they'll seriously sue when someone does)- they really try hard to be independent.  Perfect? no; always right, no- but the best thing I know of out there in terms of thorough independent testing and information.  But they're not about to take on this chore of green certification, on top of what they already do.  We need a new organization.

Somebody could make a good living doing that, actually, very fairly; and provide an invaluable resource for the rest of us.

And, such an organization could start to push for changes (Consumers Union members have considerable political clout) - like- how come, when you're buying a computer, or TV, or something similar- you have to absolutely BEG for the information on power consumption?  Why isn't it listed right up front; always?  Why don't businesses like Gaiam, which totally focuses on being "Earth-friendly" - actually give you the numbers?  What they say there is "Energy Star Compliant."  Oh, be still my heart.  What that means is; some bureaucrat thinks the energy use is "not too bad".   I WANT TO KNOW EXACTLY.

I NEED to know, exactly- because I'm off the grid; and every photon counts; today.  I not only want to know their "wattage" - which tends to be kind of meaningless - but I want average power consumption under 3 conditions; max load; half load, and light load.  Because EVERYTHING varies on how much power it actually pulls.  And I want numbers for average watt/HOURS/day, for each of those conditions- because a watt is just a measure of instantaneous power use- not power consumption per time.

Other stuff we need to know- embedded energy content; per gizmo; exactly how many ergs went into manufacturing this thing; and transporting it HERE.  Lifetime - lifetime energy cost, and cost/year.  Standby power use.  (And EVERYTHING needs a switch on it; up front; so there is NO standby power drain.)

We label our food like we care about it.  We've GOT to start labeling our energy consuming devices the same way.

The government is NOT going to do this, anytime soon- we're going to have to demand it, ourselves- and there's almost nothing out here, as an organized, authoritative green voice.

So.  Who's going to DO it?  You?  

Why not?


Beelar said...

Yeah. "Consuming Less Reports" would be good. Though I doubt they'd let you use that name...

Some folks might be interested in knowing- just how fried were the panels? Well, three of them were putting out an open circuit voltage of about 1/2 spec; qute seriously fried. The other three had OC voltages near spec (if you poked them in the right place). Damaged enough that they were definitely classifiable as scrap, and not something to be seriously relied upon, but we'll probably try using them as convenience power/small battery chargers eventually.

For those geeky enough to care like me, not only were the main connections melted/slagged, all the panels also had some parts of the silicon crystals blown up as well, along the electrodes. Only visible close up, but certainly there. And impressive!

Greenpa said...

How about "Green Liver"? :-)

Anonymous said...

This kind of real-world information is very useful indeed. Thanks for taking the time to put it together.


Crunchy Chicken said...

Holy moley! I think I'll be finished reading this by the end of January. About the time your next post is up I guess :)

Anonymous said...

Well the read was impressive and the info very useful up to a point.
What's missing: any hints about a good source for panels nearest to Puerto Rico, and, any exact instructions for lightning proofing?
URLs are fine as I am well aware of the fact that you are running like crazy just to keep falling backwards and I can relate.
Also on those URLs, a good all around source for small wind generators {boat type perhaps} and the latest ideas on lower cost reliable invertors and high efficiency refigerators. Oh yes, I know you hate reefers, but it's pretty hot here.
You seem to be getting into some tech posts now {you must be stuck inside} so these are my questions s'il tu plait.
Yes, again, this is my favorite type of post from you, Greenpa.
I hope Thor avoids you for a good long time now. Thanks.

Anonymous said...

I did take an informal poll today and my contacts agree with you that Solar World is the winner, also Trace is still the best inverter. It was not that long ago that Siemens still dominated the field. I would be very interested to know any contacts you have that are familiar with applications in the tropics. Thanks again. Oh, did I remember to mention that our residential KWH rate is now 22.5 cents? This is incentive enough to get off the grid even though we do not have reverse metering here.
I paid 71.79 for only 320 KWH last month.

e4 said...

Excellent post. Very helpful. Thank you...

Anonymous said...


I recommend the Air-X windmill, made by Southwest Windpower. Except that they don't make them anymore, but you can still find them on eBay. We have one (and another for backup) and it works great in our location -- listening to it whirl in the background at this very moment :) or check out the latest product at southwest windpower I don't have direct experience with their new windmill but I'm inclined to like the company since I like their other product.

Also, we (I live off-grid in a < 400 square-foot house with my partner) use an Avanti refrigerator, about a 4 cubic foot one. I googled Avanti and found lots of styles but no photos to show the kind we have. I don't know how much it uses, but we run our whole house on between 1.5 and 3 kilowatt-hours per day, and the fridge fits in that just fine except in the most extreme circumstances. We keep ours set pretty low, but high enough to keep the beer cold!


Greenpa said...

RC - I'm afraid I'm not going to be much help in regard to solar sources in PR - I just did a quick google on "Puerto Rico solar" (in my spare time...) and... PR solar

Nobody up front I recognize, but plenty of people who look legit. I think you're going to have way more luck than I would in sorting out which of the 475,000 hits are relevant for you- :-)

Wind generators- I've had abysmal luck with small wind; have put up/paid for 2, done repairs on both- and never had one stay working for more than like a month. I know, others have had better luck- but I've wished many times I'd just put that money into more solar panels. Besides electrical problems (an silliness- this was so long ago both put out 24VDC; at the powerhead; an idiotic idea from the get go; any good small wind alternator these days is putting out wild 3-phase power- which is converted to DC at the batteries- saving a fortune in wire costs) - both mine actually had blades - break. In relatively "normal" thunderstorm winds.

A basic problem with mainstream small wind is they are designed to run as "direct drive" alternators; which means the blades run as fast as a helicopter. Which means- one bird hit; one big hailstone- and you may be running out of balance. Won't last.

If you're interested in do-it-yourself, there's a rather new design getting some serious attention; which I like so far: New!

This thing is a good deal more productive than old "Savonius rotor" types; and, a nice thing for you- should be relatively easy to protect in a hurricane- just board it up. (I'd cover my solar panels if I were you, too- big danger not being just wind, but flying debris).

I don't THINK any of the critical design stuff on the TMA machines are covered by patents; in any case, nobody is interested in fussing you if you're just building one machine for yourself.

Fridges- again, I'm not going to be much help; it's a field that's changing constantly. Last I knew, the most efficient machines were made in Scandinavia- and their prices were not bad at all.

One word of warning there; a number of years ago I did buy a super-efficient freezer for my business; intending to run it just as a refrigerator- I was going to gimmick up the thermostat.

It didn't work. That thing was a freezer, no matter what I did; including imposing an outside power timer to limit the time it could run. What happened then was, the stuff inside near the cooling coils froze anyway- long before it would shut off.

And- then I had the idea I'd go ahead and use it as a freezer; and increase the bang for my buck by just wrapping it in more insulation.

It didn't work. The designers not only had a small fan blowing the hot air off the radiator - but they'd managed to use the whole front of the chest freezer- the metal envelope- as another radiator. It was always warm- (outside their native insulation) - wrapping it in more would have made the whole thing hot.

There used to be another do-it-yourself option in refrigeration; a couple places would sell just the DC refrigeration unit- you build the rest to suit. A good chance there to build a super-insulated unit.

Hank Roberts said...

> lightning protection

I do NOT know that this is anything close to what's needed -- it's a supplier that my local ISP told me about, when I asked how to go about preventing lightning from following an outdoor WiFi antenna's Ethernet or power lines into the house.

They've got a lot of stuff, might be something here.

Going Crunchy said...

Oh my, that was quite a read full of information. Thanks for posting that, and I'm sure I'm going to refer to it again. Shannon

Sam said...

I guess you had not come across Greener Choices by Consumer Reports.

Hank Roberts said...

Ok, so I went and looked at my one solar panel (besides the ones that keep the vehicle batteries trickle-charged) -- this one's been used for the portable 12v deep discharge battery used on long car-camping botany field trips for the phones, ham radios, recharging all the other batteries in flashlights, GPS, cameras and such.

Not to mention, the midwinter comet trip, the 12v trucker's electric blanket we used to get the sleeping bags warm (grin).

I'd bought the solar panel a couple of years ago from what used to be RealGoods, now Gaiam. And some of the cells, I noticed recently, have cracked, diagonally.

Research. Turns out it's a well known problem as of about 20 years ago:
"... If they break 10 years into operation, that initial price advantage is going to seem ... very Yugo-like.... Each silicon cell has a metal structure and wires incorporated into it, but the silicon expands and contracts at
different rates than the metal, and over time, this difference can crack the cells."

And there's a well known manufacturing technique that should reduce the problem:
"Don't use too much glue, and don't glue the cells anywhere but at their centers. The cells and the panel they are mounted on will expand, contract, flex and warp with changes in temperature and humidity. If you glue the cells too tightly to the substrate, they
will crack in time. gluing them at only one point in the center allows the cells to float freely on top of the substrate. Both can expand and flex more or less independently, and the delicate solar cells won't crack...."

And the panel I'd bought was laminated, a clear layer sealing the cells immobile and held to a fiberboard backing. Can't tell if they were glued down too, but it wouldn't matter.

It still puts out some power, don't know how long that'll last til something critical breaks.

It's no longer carried by the wholesaler, and there was never any info on where it was made, no identification on it at all.

It was sold as lightweight (yep), portable (yep), easy to take camping (yep). I'd worried on first use that the whole thing got too bendy, especially when it got hot, and had backed it with an old aluminum cooler cover to keep it from flexing. But the cells have started to crack anyhow.

Known failure mode. Design flaw. Warranty was only a year. Tsk.

Gaiam only warranties their solar panels for 90 days now, they tell me. Hmmm. What do they know?

So, Greenpa - where'd you find the ones you like? Do they make any small (5-10 watt range) ones?

Anonymous said...

PS, thank you Beany for
Greener Choices

Greenpa and friends -- it's worth a review, it could grow into something collaborative and well informed.

Solar Las Vegas said...

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