PV Array performance

[stevebea]

To the guy's out there who are doing solar jobs I have a question. Just out of curiosity, what methods are being used to ensure, track, and monitor array performance? Thanks.

 

[kbsparky]

I believe that some of the newer inverters have monitoring circuitry that allows for a connection to a PC ... I'm interested in this as well.....

 

[stevebea]

I believe that some of the newer inverters have monitoring circuitry that allows for a connection to a PC ... I'm interested in this as well.....

Thanks kbsparky. I know very little about solar but sometimes my mind wanders.:roll: How does one know if they have a bad module or panel in the array? Would a microinverter have some kind of communications port also? Thanks again.

 

[K8MHZ]

I believe that some of the newer inverters have monitoring circuitry that allows for a connection to a PC ... I'm interested in this as well.....

Give me a bit of time and I will hopefully have an answer for you. We have 3 different kinds of grid tied inverters in our lab and will be connecting them and learning their operations. Since ROI is the most compelling reason to purchase PV systems, some, if not many, inverters are equipped with performance monitors. I would think that a few of those would have a PC port.

This isn't going to happen any time soon as the conduit to the inverters is sitting in nice straight 10 foot pieces on a bench. And I'm the only one in class that seems to know how to run pipe. This will be way cool though as the class the lab is part of is brand new. The pipe I run in my class will be there for some time and become part of the college. We have a beautiful community college with a pretty fair tech center.

 

[jaggedben]

The only string inverter monitoring I've participated at all in installing has been PV Watch.

Fat Spaniel was another company. They've been bought by Power One, which I was told will be continuing their product in some form or another.

These products, as far as I know, only monitor entire array output. They basically allow for better logging of data that the inverter will do on its own. Products for more granular monitoring of string systems (that is, monitoring at the string or panel level) have only been coming on the market recently and most solar installers are probably still not very familiar with them. I did get to see Tigo up close at a conference - it looked cool - but I have never installed it or talked to a customer.

Enphase of course has its own monitoring system.

 

[tallgirl]

To the guy's out there who are doing solar jobs I have a question. Just out of curiosity, what methods are being used to ensure, track, and monitor array performance? Thanks.

Depends on the gear and the budget.

For inverters that have communications capabilities, the most basic approach is to talk to the inverter and/or charge controller and see what it has to say for itself. For larger projects, external devices may be used to monitor voltages and currents and that information is gathered by more traditional SCADA equipment.

Finally, for folks with a larger budget, environmental sensing is used to determine what the expected characteristics of the system are -- as in, is the array not producing because there is a cloud above the array? Is the array not producing because it's hot and the output voltage has fallen? Is the array not producing because the grid voltage is too high?

Communications can be globbed into a few types --

1). Proprietary. Companies like Enphase have their own very closed solution.
2). Industry standard. Companies like SMA and Morningstar use Modbus (or Canbus for Xantrex / Schneider), which is a widely used protocol.
3). "Web Based". A variety of companies provide a web interface (somehow ...) to their devices and you may only be able to view the performance through their web server.

 

[stevebea]

Depends on the gear and the budget.

For inverters that have communications capabilities, the most basic approach is to talk to the inverter and/or charge controller and see what it has to say for itself. For larger projects, external devices may be used to monitor voltages and currents and that information is gathered by more traditional SCADA equipment.

Finally, for folks with a larger budget, environmental sensing is used to determine what the expected characteristics of the system are -- as in, is the array not producing because there is a cloud above the array? Is the array not producing because it's hot and the output voltage has fallen? Is the array not producing because the grid voltage is too high?

Communications can be globbed into a few types --

1). Proprietary. Companies like Enphase have their own very closed solution.
2). Industry standard. Companies like SMA and Morningstar use Modbus (or Canbus for Xantrex / Schneider), which is a widely used protocol.
3). "Web Based". A variety of companies provide a web interface (somehow ...) to their devices and you may only be able to view the performance through their web server.

Thanks Julie. Do most inverters have communication capability?

 

[K8MHZ]

The inverters in our class can be monitored via the Internet. The instructor went online and brought up the performance charts of a PV system he installed in Indiana (I am in western Michigan). He was able to show us the difference between the output of the array both before and after installing a single axis tracking system.

Way too cool!

 

[stevebea]

The inverters in our class can be monitored via the Internet. The instructor went online and brought up the performance charts of a PV system he installed in Indiana (I am in western Michigan). He was able to show us the difference between the output of the array both before and after installing a single axis tracking system.

Way too cool!

How much of a difference did the tracking system make?

 

[K8MHZ]

How much of a difference did the tracking system make?

Actually, I was very impressed. Without the tracker the peaks formed half a sine wave maxing out at 1.6 kW at solar noon. With the tracker the graph now showed nearly a square wave with the peak being flat and four hours long as opposed to one.

A single axis tracker provides the most bang for the buck. A two axis tracker is only about 5 percent more efficient than a single axis tracker and is much more costly. When ROI is a factor, the single axis tracker wins hands down, every time.