I decided to install it because I have extra solar energy. I chose Rennai because it is a good brand. It has been working as expected since the middle of January, 2022 and it only runs for 2-3 hr at about 1 kW to refill whatever amount used. Very quiet when it runs. I know when it turns on after the event, thanks to Fronius smart-meter which records all. It uses the compressor only so far and I have not yet seen that it uses heating element as well to heat water. This specific model requires power on all the time. It is too early to assess full performance. Few drawbacks are a) runtime is not predictable, b) no control for user to switch off/on, c) no display panel to show hot water or power uses, d) no monitoring or recording data app.