Monitor generated power
In many cases the only value of interest is the generated electrical power of a PV-system. We distinguish three types of power generation monitoring:
- AC power: the total generated AC power behind the inverter
- DC string power: generated DC power of a PV-string (or strings)
- DC panel power: generated DC power of a single PV-module
The AC power can easily be taken from the inverter. Most inverters come with a monitoring solution that gives the user insight in generated power. As this sounds as a good solution, for scientific applications it mostly is not. It is in general not possible to set the measurement interval of AC power in the inverter. On cloudy days this makes it difficult to compare the AC power to, for example, the sun irradiance level. On the other hand it is difficult to verify the accuracy of the AC measurements. You will have to ‘trust’ the inverter electronics without having the possibility to recalibrate the power measurement circuits.
Use PV-Blocks to measure AC and/or DC power
PV-Blocks has the possibility to accurately measure both AC and DC power. To show how this is done two example use cases are describes in full detail: