alt Hacker NewsThe change certainly brings in some weirdness too.
For instance, I'm looking at a new hot water system. Economically speaking, I'm better off buying an oversized tank using resistive heating that I only need to heat once per day. The grid provides free power and I buy a cheaper appliance. But environmentally it sucks, as more solar needs to be rolled out to cover the additional non-peak usage (guess about 6x the power usage of a smaller tank with heatpump).
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To check I understand you: the smaller tank with heatpump would consume less energy outside the time window in which energy is free than the large tank with resistive heating, but has a higher capital cost which would outweigh the amount saved on energy?
If that's right, it's not obvious to me that building a suitably sized solar panel is environmentally worse than building a heat pump.
I get that it makes less efficient resistive heating more economical, but the tank size seems like a red herring. If you go for a heat pump you can have a larger tank anyway, and heat it during the solar peak too. A larger tank will allow you to store water at a lower temperature (instead of hotter water to be diluted). Smaller delta makes heat pump more efficient and heat loss slower.