Improvements and fixes

Inverters behind a Huawei data logger are read again after a missed reply, turbines and battery modules no longer read as offline all day, and impossible irradiation readings are left out.

• An inverter behind a Huawei data logger is read again after a missed reply, instead of dropping out of the data.
• Wind turbines and battery modules no longer read as offline for most of the day now that their connection is checked every 30 minutes.
• A plant's mean irradiation no longer includes a reading higher than the sun can deliver, and each sensor head now counts separately.