Susan Kraemar
German rooftops about this size accounted for over 1.8 GW of solar that was installed there last year. German solar power has been very rapidly expanding, because it has generous Feed-in Tariffs that pay solar owners to make power for the grid. This is a sensible policy, as the prospect of earning money is what motivates people to overcome procrastination on solar, as Al Gore pointed out a few years ago when he went to congress and suggestedthe electranet.
But the size of the systems with the most growth is interesting. As you can see from the graph below the jump, thanks to Paul Gipe at Energy Bulletin, it is not the small homeowner-sized systems that is driving this increase, so much as the next size up, that is leading the surge in solar in Germany. A ten to thirty kilowatt system takes up a larger (usable) space than most homes have – and can generate a sizable excess to the grid – for cash.
The roof of this house from the German prefab company Huf Haus has been maximized for a 30 KW to 40KW system, to make some serious money by selling power off the roof. But most houses were not designed to be such efficient solar power stations!
Typically, you need a commercial building-sized space. For 30 KW, you need about 1,500 square feet of usable space. Many houses, even though they may have an adequate footprint, are made unusable for large solar by all the little gables and tree shading they can have.
But this is about the size of the roofs in Germany that are supplying the most in this graph. So it looks as if Huf Haus type McMansions, as well as churches, farm fields and small commercial buildings, are supplying the most growth in German solar.
The next size up, 30 – 100 MW would be made possible by the space on big box stores, or college parking lots. And to build a 1 MW system, you’d need about a whole city block – so this would be only possible on large apartment complexes, universities or large-scale manufacturing plants like BMW.
The under 10 KW systems accounted for the least growth. Since most German homes probably need 4 to 8 KW systems just to supply their own needs, because of their insolation and mod cons, it would appear that the financial incentive of the Feed-in Tariff amount to be earned on a much smaller excess is lacking. The potential earnings are not enough to overcome the inertia. Feed-in Tariffs have driven Spain, Germany and Italy to world leadership in solar (Italy’s solar is growing at 3 times the pace of the USA using Feed-in Tariffs) but what this graph graphically illustrates is that the earnings have to be worth it.
This story by Susan Kraemar was on Cleantechnica
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