Solar Energy Pt 2

In part 1, I covered the two different types of solar power and the basic on cost and ROI.

This is part 2. I’ll cover some future developments, specifically thin-film technologies which could revolutionize solar power. But TF has its drawbacks too, specifically low power efficiency per sq meter.

This entry I wanted to cover thin-film based technologies. This is a branch of photovoltaic (PV) solar energy.

There are numerous entrants into the thin-film market. I cant cover them all or I’ll be here all day writing.

I’ll start with the one with the biggest brand recognition, mostly due to who is investing in it (Google), and that is Nanosolar. They are producing a type of cell called CIGS (Copper indium gallium selenide). A few weeks ago they posted a video on their blog about their new roll-to-roll printer that would allow them to produce 1GW of solar cells per year. Now granted, that’s not the only piece in the manufacturing pipeline and they didn’t disclose the efficiency of the cells produced from the unit, but the impact is huge if it can really produce that volume of cells. (some back of the envelope math says that if they run that unit 8 hrs/day, 7 days a week, 52 wks/yr, the solar cells that are made will be 12% efficient, for them to produce cells less than 8% efficient would be a waste because it wouldn’t be cost effective in terms of installation)

The most amazing thing is the cost – Nanosolar claims that tool only cost them $1.65M. At $1/Watt, the unit is printing revenue of $1B/yr. Even at 1c/Watt (an unheard of price for solar power, considering the going rate today is 400x that amount) the unit would still be printing $10M/yr in revenue (6x capex). Beyond that, they state that there is the possibility that they could run the tool faster – up to 2,000ft/minute from the current 100ft/minute. This would result in 20GW of solar cells per year from the single tool. To place that in a useful context, 20GW of solar panels installed on rooftops in California could accommodate 75% of the difference between baseload and peak power demand on the sunniest, hottest days of the year. It would certainly be the end of rolling blackouts.

Next up is First Solar. They are producing a type of thin film cell using CdTe (cadmium-telluride). They are further along than Nanosolar, since they are producing panels and implementing projects like a 40MW utility scale project in Germany. And their cost is cheap too – about 3.25Eur/Watt installed ($5/W at today’s exchange rates, stupid weak dollar), compared to the standard cost of $7/Watt. The problem is land – the efficiency of thin film cells is lower and the installation is using 75W panels for a total of 550,000 panels and roughly 300 acres. So while the price looks great, putting 18 panels on your roof will only generate 1.3kW of energy, or 13 100W light bulbs. More efficient panels are needed for smaller installations.

Another CIGS producer is Global Solar in Arizona. They recently expanded their factory in AZ and opened a factory in Germany.

Not everything is peaches and cream however. A few thin film companies have had to delay, scale back or retool their production plans. Miasole had to retool their commercial production line after seeing low efficiencies, even though their research and development production line saw the 8-10% target they were hoping for.

As I mentioned at the beginning of part 1, the problem isn’t the research of the technology. Its the mass production milestone. To go from 1MW to 10MW to 100MW and 1000MW in annual production capacity over the next five years to provide the energy we need.

Even with the 10% efficiency targeted, panels currently in production are only rated at 75W versus 224W silicon PV panels that are available today. The lower rating or the panel increases the amount of land needed and makes rooftop installations less cost effective due to the lack of space and limited amount of panels that can be installed. A 1500 sq ft ranch home might be able to put 20 200W panels on their roof for a 4kW installation, but at 75W the output would only be 1.5kW. Due to the way the economics work with small installations, the payback time could be much longer because of the increased $/Watt cost as well as a decreased power output (only 30% cheaper for providing a smaller part of your electric consumption).

The sweet spot for rooftop installations is about 3kW-5kW, this provides enough power to be worthwhile and still be around only 20-25 panels, so we’ll need to get thin film panels up around 135-150W. I’m confident we’ll get there, but it might take a few years. In the mean time, the panels will be targeted towards utility scale projects.

With solar power there are three key aspects: price, efficiency, and quantity available. Right now we have efficiency in the bulk PV market, and in the thin film we will soon have price and quantity, with questionable efficiency.

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