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Author: derek the solarboi

I've worked in solar for 2014, working everything from install, service, and management. I have a passion for sharing how things work and what people can expect from their systems as they age and need service.

Issue Solved: Fronius MPPT1 dropping production

Issue Solved: Fronius MPPT1 dropping production

Published by derek the solarboi on December 14, 2023

I’ve been fighting with two identically installed Fronius Symo Advanced (10kW) inverters over the last month, and I think I’ve finally fixed it. It’s very strange, and seems to be an issue in the firmware of the inverter, itself.

The installation looks like this. They are two carports (only one is pictured), identically oriented, with north, south, east, and west arrays. The east and west arrays are smaller and hooked up to a Fronius Primo 3.8 on each carport, obviously using different MPPTs for different arrays. The same thing is the case for the north and south arrays: they’re hooked up to a Symo Advanced 10.0 at each carport.

The problem is that MPPT1, hooked up to the north array on each carport, drops off during high irradiance days. Check it out.

You can see when it starts producing in the morning, drops to nothing, then later in the day, it jumps back up and starts producing. Sometimes it takes until after noon, and sometimes, like pictured above, it comes back up when the irradiance dips and MPPT2 produces less for a bit.

This only happens on higher irradiance days with good, bright sun, and on both carports. On cloudier days, both north and south arrays on both carports produce equally, as you’d expect with diffuse sun.

Fronius tech support was no help with this one. We made sure firmware was up to date (fro34310 at the time, for those following along), but beyond that they were extremely confident that there was something wrong with our wiring or our array setup, but couldn’t give me proper direction. It may have simply been the one tech I was talking to, but he was extremely frustratingly not budging on his assessment. It doesn’t help that there are no error codes triggered with this problem.

In troubleshooting, I couldn’t nail any issues to our set up for rapid shutdown devices; everything on site is rated to work with each other and is set up properly. Had some previous issues with dueling RSD transmitters tripping arc faults that I got sorted, so very confident that’s not an issue any more.

When I was onsite, however, I was able to shut off DC to the inverter and turn it back on within about 10-20 seconds, and the inverter jumped up to the proper production on all strings, so it would seem there’s nothing instantaneous in the array that’s causing MPPT strangeness.

Finally, I swapped MPPTs between arrays, putting the south array (highest producing) on MPPT1 and the north array (lowest producing) on MPPT2. After giving it some time, I think this one change solved my issue.

You can see in comparison to the first graph, that the north arrays seem to have no more issues with dropping off in production. The south arrays didn’t have the irradiance on this day that they had in the previous graph, but it’s enough that the north arrays would have dropped off if they were wired as they were originally.

My reckon is that this is directly related to the inverter wigging out when MPPT2 gets 5x or more the production of MPPT1, and only resets when MPPT2 stops rising. I’d imagine that most installations would put the main and highest producing arrays on MPPT1 by default anyway, so this issue would be very rarely seen. If you’re having this issue, try making sure MPPT1 gets the most production between the two, and it might fix it for you.

Weird weird issue.

Solar Adoption in Rural America

Published by derek the solarboi on November 22, 2023

From Mike De Socio at CNET:

“We were able to find that adoption of these technologies is highly related to income,” Mayfield said. “We also find that education is also a main factor of these technologies.” In other words, rural Americans with higher incomes and more education are more likely to put solar panels on their roof or buy a heat pump.

I mean, yep.

And the big “solution” many companies turn to for low-income and low-education folks, is leasing. I’ve met maybe a handful of people who were a big fan of their lease, but they were markedly at the beginning of the craze in the early 2010s when the deals were much better. However, most leaseholders I’ve encountered, especially in recent times, have become cynical about solar, mainly due to poor service.

Solar leasing companies historically have very few service people available, and it often takes months of hassle to get people to come out. The usual scenario involves residents reaching out to the leasing company for months without a response or with dismissive gestures. As a last resort, the resident stops paying the monthly bill, finally grabbing the attention of the company. However, instead of getting someone to fix the system, the company contacts someone like me to disable the system outright until payment continues.

Every single one of those kinds of jobs I’ve seen are on low-income housing. When these leasing companies mess up, it reinforces the belief that solar is a scam. Paired with fast-talking salesmen with no morals, leasing is the fastest way to introduce solar to low-income Americans — and a recipe for alienation.

Best way to educate, as with anything you want to incentivize, is to increase the accessibility of ownership.

Electric DramaticElectric Dramatic logo

Electric Dramatic

Published by derek the solarboi on August 28, 2023

Because I’m incapable of not starting side projects, welcome to Electric Dramatic, where we get you up to date, baby!

This is actually born out of a previous side project called RVTheory, where I used electrician beef with some RV technicians to parody the “comment electrician”, who always knows so much in their head but probably have never been called on their bullshit. RVTheory was ultimately unsustainable and too niche, but it did feel like a stepping stone to something else, I just couldn’t figure it out. And also I probably got distracted with something more important.

However, step in Cy Porter, a home inspector on all the social media platforms. Cy Porter is fairly well respected, but showed his colors recently as an attention hog in his videos. The whole saga is pretty thick, and I realized what people need is not a parody by someone who can’t keep up with it, but an explainer site for the occasional drama that happens in the electrical social media community. And so, Electric Dramatic was born with its first post: Bye, Cy.

Solar, but in space!!!

Published by derek the solarboi on June 16, 2023

From Corey S. Powell at WSJ:

In this age of wireless everything, engineers are trying to perform the ultimate act of cord-cutting: generating abundant solar electricity in space and beaming it to the ground, no power cables required.

The idea and how it works is basically putting a huge solar array in space, and beaming it the power via microwave like a huge wireless charger, which is genuinely cool. But it’s not like we’d suddenly be getting rid of large power farms on earth:

Bringing space-based solar power to the masses will require not just a lot of satellites but also a lot of antenna farms on the ground. Two gigawatts of beamed power would require about 25 square miles of receiver, according to a Solaris-funded report by the research firm Roland Berger.

Doing some googling, 2 GW of solar farm would likely also require close to 25 square miles of land use, but you’d get less interruption due to weather since microwaves don’t give a fuck about clouds. And I’m sure a lot of this tech will continue to miniaturize over time.

Regardless, this kind of tech development excites me, even though it’s still in early stages.