PV Efficiency:

Going through my morning email newsletters, I came across a press release from a company called LONGi, announcing a new record of solar module output efficiency of 20.41 percent!  The exclamation mark was theirs, because another tenth of a percent doesn’t get me all that excited.  Last week some outfit announced their record output of over 40 percent.  A close read of that announcement showed that their output was achieved with concentrating lenses. Concentrating lenses in turn require that extra effort must be made in getting stuff pointed straight at the sun or everything goes to pot in a hurry.

Any solar module will output more electricity if you put more light on it.  The problem is that in addition to the extra complications and power, you get extra heat.  Some years ago somebody was selling used panels from a concentrating solar farm and they looked like trays of fresh-baked cookies, all warm and brown.

Sure, somebody with special limitations on weight or available space may benefit from superduper efficient panels, but you can count on special panels having a special price.  For my solar boat, the standard “B” modules I used were cheap, but heavy.  I compensated by just making the roof a little lower instead of spending way more for lighter modules and the boat has so far stayed right side up.  Always have the bottom of the boat heavier than the top!

If you have the space, though, the real efficiency in a solar power system is how many watts you can get for your dollars.  More solar sellers seem to be using that criteria in their advertising nowadays, showing a price in $/W.  This is seems to be a trend that John started with Sun Electronics, as I have always seen his panels priced that way.

Many of the panels in my array are, shall we say, not “Grade A” and I am happy if they put out anything close to the label rating, regardless of theoretical efficiency.  I’m building power levels by shear quantity of modules, counting my efficiency in pennies per watt.  As for improving efficiency, blowing the fallen oak leaves off the array helps and it would probably be a good idea to break out the long-handled scrub mop every now and then… it helps!

So, if your idea of efficiency is getting the most for your money, give the Sun Electronics crew a call.  They almost always have deals that are even better than the published prices.

Neal

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