Ven Sonata’s query is simple: If the falling cost of installing a photovoltaic (PV) system has killed off the viability of solar hot water systems, as GBA senior editor Martin Holladay believes, does it also represent a threat to the beloved ductless minisplit for heating and cooling?
“Is it possible that heat pumps themselves are at least wounded?” Sonata writes in a Q&A post at GreenBuildingAdvisor. “PV at $3.50 [per] watt installed. Note that heat pumps are still great for all places where PV is impossible.”
Efficient, relatively inexpensive, and able to function even in below-zero temperatures, ductless minisplits have become a first choice for many builders specializing in high-performance houses. But is it possible that electric resistance heat powered by PV is now a better choice?
That’s the question for this Q&A Spotlight. Be prepared to crunch some numbers.
Wounded, maybe, but far from dead
Even though the cost of solar electricity has dropped dramatically, the numbers still aren’t there for a wholesale conversion from heat pumps to PV-powered resistance heating, writes Dana Dorsett. At least for the moment.
“Heat pumps are only wounded when the cost of electricity (from PV or any other source) falls to such a ridiculously low level that the up-front cost of the heat pump relative to resistance heating is not viable on a lifecycle cost basis,” he writes. “At 3 US cents/kWh, that may be compelling, but most of the world is paying three to 10 times that much for electricity.”
The levelized lifecycle cost of grid-tied PV, Dorsett continues, is typically greater than 10 cents/kWh for residential systems, much greater in some areas, even as large-scale arrays can produce power for less than that.
That said, there are signs the cost of PV will continue to fall…
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