Improvements and fixes

A battery storage system and a second generation of a solar data logger can now be added. Adding or updating several components of one plant at once no longer fails.

• A battery storage system can now be added, reading its boxes, racks and converters from the plant's SCADA at one-minute resolution.
• A second generation of a solar data logger can now be added, reading the inverters and the environment sensors behind it.
• Adding or updating inverters, combiner boxes and strings no longer fails when several components of one plant are processed at once.
• Combiner boxes and strings now carry their own loss figures beside the inverter loss.
• A feed-in meter's data now comes from the meter configured on the plant.