HOYMILES
Recommended are HM inverters with a single power stage / MPPT tracker. Rationale:
The HM Hoymiles inverter series are build using 1 or 2 independent power stages / MPPT trackers. The larger models use two solar modules for each power stage / MPPT tracker. A simplified model of a 4 channel inverter is shown in the diagram below. This diagram shows the 4 channels, the 2 independent power stages (denoted as R Last) and the shunts (denoted as R Shunt) for the 4 channels. The shunts are used for current measurement and power control such that the requested power is delivered by the two power stages.
When connected to a battery the inverter will have all + and - connections connected. There will be small resistance differences in the shunts and the cables / plugs used to make this connection. This causes current to flow over the ground connection between both power stages which will provide an incorrect current reading to the power stages. This will lead to unequal power generation in both stages.
Well, Yes and No.
In Red you see the Capacitors of an HM-600. When empty, they have the capability to absord significant amount of current, initial calculations estimate that the initial charging current should easily be over 100A.
I think there is a lot of luck involved if you connect the battery without precharging.
In any case, it really affects the durability of the electrolytic capacitors.
- We have never heard (yet) of anyone having destroyed his inverter due to inrush of current from the battery.
- However:
- Your Inverter Manual as well as panels advice to never connect/disconnet the cables while there is solar power to the panels
- It is documented everywhere that one must pre-charge the capacitors before connecting a battery
- It is actually "piece of cake" you can achieve this using a 3EUR resistance or even with a 230V incandescent light Bulb!
For a full explanation, look here https://github.com/helgeerbe/OpenDTU-OnBattery/wiki/Battery%E2%80%90Tipps#do-i-need-to-pre-charge-my-hoymiles-before-connecting-it-to-the-battery
There are many videos explaining the reasons and how to do it:
https://youtu.be/ZlrtmJRfSP8?t=72
One with a 48V light bulb: https://www.youtube.com/watch?v=DOrJ5AH9yjM
... and one with a 230V light bulb: https://youtu.be/0M_7s39E3Ds?t=313
If you have a Battery with "Soft-Start" (like Pylontech and many other brands), you do not need pre-charge.
According to Hoymiles, the inverters have a: Derating triggering temperature of 85°C Derating factor of 14% Shutdown temperature of 90°C **Restart temperature of 85°C ** Restart interval of 0 (meaning that, once it shuts down, a Hoymiles inverter will continually check to see if it has reached the required restart temperature, allowing the inverter to begin converting power as fast as possible)
The graph below shows the power reduction relative to the temperature of these models of Hoymiles microinverters. As you can see, power drops rapidly once the internal temperature of the microinverter rises past 90°C.
However, once the inverter reaches the restart temperature of 85°C once more, you can see that the power immediately rises back up to 100% — no waiting around for the power to gradually rebuild once the inverter restarts.
(to be translated) Es müssen alle Gehäuseteile der Anlage auf eine Erdungsschiene geführt werden, sowie die Erdungsanschlüsse der Überspannungsableiter. Beim Hoymiles Wechselrichter gibts auch eine Schraube für die Erdung. Die Erdungsschiene wird dann mit der Erdung verbunden, im Haus wäre das die Potentialausgleichsschiene. Die Plus- und Minuspole sowohl der Batterie/Akku als auch der Solar-Panel-Leitungen werden nicht geerdet - sie sollen potentialfrei sein!
All housing parts of the system must be connected to an earthing bar, as well as the earthing connections of the surge arresters. The Hoymiles inverter also has a screw for earthing. The earthing bar is then connected to the earthing, in the house this would be the potential equalisation bar. The positive and negative poles of both the battery and the solar panel cables are not earthed - they should be potential-free!
There has been a case of a member noticing a very long time required until the inverter lowered its power in order to match the Dynamic Power Limiter's values.
If you experience such a situation, you may need to check the Power Ramp Rate (PRR) values under Active Power Control.
Power Ramp Rate should be between 0.33% und 100% of the total power of your inverter per Second. For example, for a HM-1000, a Power Ramp Rate of 10% per second means that the inverter can adjust at a rate of 100W per second.
You can find the Power Ramp Rate by selecting Show Grid Profile and expanding the Active Control Panel
Users with a Hoymiles Installer account can modify the Power Ramp Rate