Everything Solar Forum

This week we take a look at transformers - those metal cylinders that you almost never notice hanging on phone poles until they fail and disrupt your life - possibly for months. Each Tuesday at noon (Eastern) solarPVtraining.com hosts a Zoom sessions for students (or anyone, really) interested in solar. Generally discussion focuses on technical questions, problems or troubleshooting - or just what is happening in solar that week.

Transformer are becoming a focal point nowadays, even in the utility scale solar. Dennis is right in how utilities consider the back-feed. For example, if there is a transformer serving several house and these houses have solar, then the sum of all PV should not exceed 90% capacity of the transformer. In Florida, several utilities put the upgrade cost into the last house to add solar, if needed. Now, that I find it unfair. I understand that the transformer needs to be upgraded, but that cost needs to be absorbed by all the houses that added solar to that transformer as well as the utility, since it is capital equipment.  it can also be weighted depends of the PV system at each house, but definitely not paid by the last to come.  

When I ran my overhead cables underground, as part of that upgrade, I had them put in a 50KW trans as an upgrade to my old 15KW. There are three houses that run off it. I wanted the extra power "gap" so I would have plenty of room for any PV I continued to add Plus wind. I most likely will be the only one to have power production. I of course paid for the trans. I think it was about $900. Most of the cost was deferred as a necessary upgrade because of how long ago the original "stuff" was run. The original cables were like a #4 which was really small, etc.. The cost was very reasonable over all. The new ones were 3/0 AWG which dropped my voltages when I was producing, a good thing because with the #4 service feed, my voltages were running into the 250 vac range when really sunny. Now they are "normal".

PPL is my provider.

That was fair, It was a necessary upgrade indeed.

 Here I found the issue about Tx upgrade in communities where several houses have solar, and some of them the PV size is higher than initial installation, as they were adding more PV down the road without notifying the utility.