If you use it to heat a house in winter, wouldn’t losses be very low?
Usually you can do something like light->electricity->battery[x]->electricity->heatpump->heat. The efficient in the heatpump is like 300%, i.e. for every 1 Joule stored in the battery, the heatpump extracts 2 Joules from the ambient and sends 3 Joules of heat inside your home.
This device is something like light->bath[y]->heat.
If you assume both get the same amount of light, it's misleading to compare the energy stored in battery[x] and bath[y], because the first has a magic x3 later that comes from the heat pump. This sods not depends on the exact setup, but it's an important difference between "work" and "heat" in a thermal machine.
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Usually you can do something like light->electricity->battery[x]->electricity->heatpump->heat. The efficient in the heatpump is like 300%, i.e. for every 1 Joule stored in the battery, the heatpump extracts 2 Joules from the ambient and sends 3 Joules of heat inside your home.
This device is something like light->bath[y]->heat.
If you assume both get the same amount of light, it's misleading to compare the energy stored in battery[x] and bath[y], because the first has a magic x3 later that comes from the heat pump. This sods not depends on the exact setup, but it's an important difference between "work" and "heat" in a thermal machine.