I have a solaredge inverter and I’ve been using an EmonTX 3.4 since almost the beginning. I enabled the Modbus over TCP protocol on my inverter and can poll for SunSpec data on it any time. It’s great, provides a lot of info, including total generation and also instantaneous DC, AC values, heatsink temp, etc. But there’s a catch. SolarEdge has a user portal where one can follow daily generation, updated at 15 min intervals. I checked a full day, and have collected the following generation data:
- SolarEdge portal: 19.3 kWh
- Inverter, night to night kWh difference: 19.3 kWh
- Inverter, sum(Watts queried each minute once) / 60 / 1000: 18.863 kWh
- emonTx: 18.5 kWh
So the cumulative energy values are the same for the portal and my inverter. The energy calculated from the instantaneous values is less by about 2.3%, and what my emonTx shows is less by about 4.3%. Which is more accurate? EmonTx is sampling instantaneous values each 10 seconds and provides true RMS metrics. It should be pretty accurate, if the sensors are accurate. But I just don’t know… I still intend to calibrate my emonTx using some method, but I thought checking out the data provided by the inverter might worth a shot. Any ideas?