I retract all scoffing remarks regarding Nanosolar

» 20 Dec 2007

Historically, I have spent a fair amount of time deriding Nanosolar for claiming that they would build a 430 MW/year solar cell factory by the end of 2007.

On the one hand, they have only 10 days to prove me wrong. I don’t think they will have ramped production up to 430 MW/year. On the other hand, they are shipping a thin film module created through a printing process. That alone is an impressive feat. They win the prize, soaring above the Aonian Mount, while pursuing things unattempted yet in prose or rhyme (well, maybe attempted in rhyme).

Nanosolar is claiming module costs of 1 $/W; the US solar industry is now selling around 5 $/W.

It looks like they have beaten:

Ascent Solar (thin film, CIGS, probaby through vacuum deposition)
Konarka (thin film, printed, organic cells)
Heliovolt (thin film, printed, CIGS cells)
SoloPower (thin film, CIGS, but electroplated, not printed)
Miasole (thin film, CIGS, but not printed)
Solyndra (thin-film CIGS, unknown process, but they're hiring people with semiconductor process experience)

But have they hit grid parity? Maybe.

First off, $/W is a dumb metric. The W refers to the peak power, so if you buy a panel that peaks at 200 W for $800, you’re paying $4/W. It’s stupid, but it’s easy to measure, and it’s easy for journalists to quote.

A better metric is $/kWh, where kWh is a unit of energy. That’s harder to talk about, because you have to talk about average production over the course of a year, which changes with location, weather, age of the panel, and so on.

The sun that hits the ground peaks around 1000 W/m^2; you might get 20% of that on average, once you factor in night, clouds, and the like.

There are about 10,000 hours in a year, so I’d expect 200 W * 10,000 hours * 10% efficiency = 200 kWh/year for a square meter. In Massachusetts, where I live, that’s worth about $40 ($0.20 per kWh). (Did I get those calculations right?)

Conventional panels of around 10% efficiency are about $1500/m^2 (say, 2 Evergreen 200 W panels for $750 each?). Given panel life of about 20 years and the added expense of installation, an inverter, and maintenance, I think solar is still off from grid parity by a factor of 2-4 in Massachusetts (not counting Nanosolar).

If Nanosolar is telling the truth, they may have just hit grid parity.