Comments on: Graph Of The Day: Super-Sizing Rooftop Solar Systems

By: Ronald Brak

Ronald Brak — Wed, 29 May 2013 07:34:00 +0000

That’s a chart of research results, which isn’t the same as what’s going on people’s roofs. It was technically possible to get 20% efficient solar cells 7 years ago, but no one was putting them on their roofs because of the expense. Nowadays it’s not uncommon for high end systems to have efficiencies of or close to 20%.

By: Bob_Wallace

Bob_Wallace — Wed, 29 May 2013 06:53:00 +0000

Thinking more about it…

The best metric would probably watts per square foot.

Back earlier, when cells were a lot more expensive, cells weren’t trimmed square but a roundish slice was used. That meant that some of the panel space didn’t contain collection material. If you look at pictures of older panels you’ll see diamond-shaped areas between cells.

Going back even earlier, there was a lot of dead space in solar panels, as you can see with this 30 year old panel..

.http://i2.wp.com/cleantechnica.com/files/2012/10/Martin-Halloway-with-his-30-year-old-solar-panel.jpg?resize=275%2C432

And look at how much of the cell face is covered with connector strips. Those have been greatly shrunk over the years.

By: Bob_Wallace

Bob_Wallace — Wed, 29 May 2013 00:47:00 +0000

I’m not sure that’s the data you should use. Best/champion cells can be quite different from what is sold for use.

I wouldn’t be surprised to find that commonly sold panels are much improved over the last decade.

Best I recall my ~13 year old panels are around 12%. There are several on the market now that are 16%+ efficient.

http://sroeco.com/solar/most-efficient-solar-panels

By: James Wimberley

James Wimberley — Wed, 29 May 2013 00:19:00 +0000

I'm going by the NREL chart of record efficiencies for each cell type. Multicrystalline silicon, the workhorse, has been stuck near 20% for a decade. Production modules are less efficient but you'd expect the gap to lab stuff to be fairly constant. The rapid gains in efficiency have been in high-end multijunction cells, which sell to the Pentagon and NASA for prices out of your or my pocketbook; and at the bottom end, in cheap organic and dye cells, which are catching up from a low base.

By: Ronald Brak

Ronald Brak — Tue, 28 May 2013 22:52:00 +0000

Nani? There’s been a significant improvement in average efficiency since 2008. I’d look it up but I slept in and now have to get into a diseased filled tube to get into town instead of walking.

By: James Wimberley

James Wimberley — Tue, 28 May 2013 21:35:00 +0000

Oh? The efficiency gains have been slight, so the output per square metre hasn’t changed much. Weight is down by more and the packaging in better.

By: Ian Arnell

Ian Arnell — Tue, 28 May 2013 20:35:00 +0000

great graph! This will really help illustrate to people just how much solar has changed from their perception of it. No longer is it gigantic bulky systems. They can do so much with sleeker and smaller panels now