Polar night are focused on storage for a few days or a week, so balancing between windy and calm periods.

That means they need enough heat pipes to recharge and empty the store that quickly, which would become very expensive if the store were a larger volume at low temperature difference.

April 10, 2026 - 09:23 UTC

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Inter seasonal summer-winter storage is a different market, where you can have more ratio of soil to less pipe. Even so, the ground loop pipes are often the most expensive part of a GSHP system.

Think its like lithium vs vanadium vs pumped storage - different tech for different storage durations.
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Yes this is what I was saying - you can do one or the other but there are reasons for taking the "big above-ground tank" approach. Plus, at the high temps they can use heat to generate electricity (nowhere near as efficient as using the heat for heat, but it's another arrow in the quiver I guess.)
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