Thoughts on Solar

At Run on Sun we like to think of ourselves as true Solar Pros - years of experience, NABCEP certified, yadda, yadda, yadda!  But this post is about doing something wrong (nicely done, Jim) and having to figure out a way to fix it (thank you, Sara!).  We recount it here because it might help some of our colleagues who just might make the same mistake!

Run on Sun is a huge Enphase shop, and one of the reasons why is the great monitoring that we get for every installation.  For installers, we can see module-level data that allows us to determine not only if there is a problem with the array, but where that problem is!  (Contrast this with a string array, where determining where a problem resides can be an error-prone and time-consuming process.) 
Check out this sample from one of our systems:

This is from a recent install using LG 360 Watt, back-contact modules with Enphase IQ6+ microinverters. As you can see this is a very consistent array with the output power ranging from 288 to 291 Watts at each module.  But you might ask yourself, how does the system know which module/microinverter is which?  The answer is easy - each microinverter has an associated serial number, and it sends that serial number to the monitoring device (called an Envoy) when it reports its performance.  When the installer “builds” the array in the cloud, she maps the serial numbers from the microinverters to the layout as installed.

To facilitate that mapping, Enphase provides a peel-off label on each microinverter.  The installer removes the sticker and places it on a map, to be pared with the online layout.  When we are doing our installs, I am often the person responsible for collecting the labels onto the map, and then later using that map to build the system online.  I’ve been doing this for years, and never had a problem.

Until the other day.

I got back to the office, ready to build out our array online, only to discover - there’s no map!  Mind you, I remember clearly creating the map, and I would have sworn I put it in the car right after doing so, but it was nowhere to be found!  Yikes!  Now what do we do?

To be sure, the serial number were still on the microinverters, but they could not be read from where they are located on the roof!  Ugh - we could remove the modules (of our otherwise operational system) but that would be a huge amount of work - there has got to be a better way!

Cue Sara - Problem Solver Extraordinaire!

Indeed there was as Project Coordinator, and problem solver extraordinaire, Sara Pavey quickly observed.  We could connect to the Envoy using a smart phone (it has a WiFi hot spot built in), and look at the data coming from the array.  If we were to shade one module at a time, we could see which microinverter’s power output went to zero, and then record the corresponding serial number!

Jim paying dues on the roof for losing the map!

One module at a time, we covered a portion of the module so that we could detect it’s loss of output, and record that serial number in the proper position.  (The per-microinverter data is not instantaneous, so we had to wait until the Envoy polled each one to detect the change.  Hint to Enphase: it would be nice to be able to get that data in real time, as that would greatly speed up the process!  Maybe as part of a special, troubleshooting-for-idiots mode?)

Nevertheless, with a minimum of fuss and bother, after an hour we had mapped all twenty-six microinverters, without having to unbolt a single module.  Well done, Sara, you more than earned your keep that day!

(Oh, and we now take a picture of the map as soon as it is completed!)

So there you go folks, live and learn!  If anyone out there has faced this problem in the field, how did you resolve it?  We would love to hear from you in the comments below!