In a recent webinar, Gabe Abbott, director of business development at Locus Energy, and Ilen Zazueta-Hall, director of residential product management at Enphase Energy, answered listener questions regarding solar monitoring systems. Here is a recap. To listen to the full webinar, click here.
- Q: Solar Power World: How is monitoring a PV system like monitoring traditional nuclear or other power plants, and how is it different?
A: Abbott: I think there are some core elements of monitoring that have nothing to do with solar, and are more about just understanding equipment and assets and how they’re performing. There are basic requirements concerning alerting and reporting information and getting data in real time. However, I think one of the key differences for solar is that generation is very much tied to environmental conditions, weather and climate. Data collection from meters and devices is one thing, but coupling that with environmental data provides conxtext and insight into what’s happening in the environment and how it impacts performance. What is the solar irradiance at the site? How is it impacting performance? That’s where solar monitoring really differentiates itself from what you see in some conventional energy sources.
- Q: SPW: What type of data are you examining at when you’re looking to determine if and when you may need maintenance?
A: Abbott: If you are getting data from an inverter directly, that could include DC information or fault codes that help you identify things like ground faults, and even provide insight into issues that may not be catastrophic at the moment. An example of this is a medium or low priority inverter fault that is causing the inverter to reset itself on a regular basis. Customers use those fault trends to demonstrate to their manufacturers that there may be a larger issue coming, and in some cases they can proactively issue a replacement request and get that unit replaced before it cuts out. There are other variables you can pick up in the data around the DC voltage that’s flowing through an inverter which could help you find a string that is down or some other issue that may not be recognizable at a large scale as a binary problem, but may be something that’s driving incremental production loss.
A: Zazueta-Hall: I’ll add that in a microinverter system specifically where you’re able to get the DC voltage and current, and AC voltage frequency and temperature for an individual module, you can go even a little further down and identify specifically where in the array the underperformance is coming from. Do you have a specific module out? Often cabling issues can be identified this way.
- Q: SPW: How accurate is residential microinverter monitoring?
A: Zazueta-Hall: There are varying accuracy levels depending on how you do measurement. For example, for Enphase monitoring there’s aggregation of all the individual microinverter data. That’s collected with 5% accuracy. Then, there is also our meter data in which we’re providing revenue-grade meter accuracy. That’s specifically for the power measurement, the accumulated energy accuracy. Typically that’s where you want very high accuracy, because that’s what required in some of the third party ownership (TPO) scenarios.
- Q: SPW: Is there a way to use monitoring to determine voltage and current harmonics levels in generated power?
A: Abbott: I think it really comes down to what you’re measuring. There are certainly some meters that will give you basic energy data, and some that will provide some additional insights into power quality. That’s everything from voltage, to current to phase angle, power factor and a number of other variables that will allow you to understand what’s happening on the grid. We’ve seen customers really interested in understanding simply the AC grid voltage and how it is interacting with their inverters. If the utility sends out a large voltage spike which shuts down inverters, that’s the main thing they will want to understand. I think monitoring providers are in a good position to offer that level of insight to installers and financiers, to help them understand the root cause of their energy loss. Those power quality variables can be really useful for such cases.
- Q: SPW: What are the biggest trends you see in monitoring for 2015?
A: Abbott: We’re seeing many customers and fleet operators now have a much better handle on day-to-day business processes, and they’re starting to really scale and drive a lot more volume through their businesses. They’re starting to look more closely at the data itself and trying to identify issues remotely through analysis, rather than on site. There are various machine learning techniques that you can apply to this data to understand performance trends and shared characteristics between sites, as well as the core causes of underperformance. This can help you better inform both your O&M teams and sales teams in terms of how to price those systems.
Also read:
Why is solar monitoring important?
How and why solar inverters and monitoring work together
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