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Finland to build world’s largest air-to-water heat pump plant
(www.pv-magazine.com)
This is a most excellent place for technology news and articles.
What about when you don't have excess solar power? People need heat when they need heat, not just on sunny days. So, you'd need a massive battery for that, which has some undesirable implications. Instead, a thermal plant (be it solar, geothermal, or nuclear) can be designed to reliably satisfy heating and electricity demand with excess electricity going to hydrogen production for emissions-free steel, fertilizer, and vehicle fuel.