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Given the fallen prices of photovoltaic panels, it is frequently cheaper to use them rather than to build a passive collector, particularly if you have to deal
by jws 8y ago
Given the fallen prices of photovoltaic panels, it is frequently cheaper to use them rather than to build a passive collector, particularly if you have to deal with freezing weather and already have some photovoltaic infrastructure in place.
- kragen 8y agoPhotovoltaic panels still cost €0.19 per peak watt, wholesale (https://www.solarserver.de/service-tools/photovoltaik-preisindex.html https://www.solarserver.de/service-tools/photovoltaik-preisi...). Lowe's lists 50 feet of 3-inch corrugated black plastic flex pipe at US$31.98 (https://www.lowes.com/pd/ADS-3-in-x-50-ft-Corrugated-Solid-Pipe/50148228 https://www.lowes.com/pd/ADS-3-in-x-50-ft-Corrugated-Solid-P...), which works out to 1.16 m² and thus 1160 peak watts, which is 2.7¢ per peak watt — 9¢ per peak watt if you figure that the collector is only 25% efficient (this depends on the temperature). Currently US$1 ≈ €0.874, so that's €0.079 per peak watt. That pipe is HDPE, and corrugated to boot, so it can go through quite a few freeze/thaw cycles before it starts leaking. It's true that it won't provide you hot water when it's freezing outside unless you put it under glass or at least plastic, though, and that drives the cost up. I was expecting to find that you were ridiculously wrong, but actually it seems like the costs for a passive solar collector that can produce hot water in freezing weather actually might be about equal, or in any case no less than half the cost of photovoltaic. Bravo! And thank you for the insight!