The email that started the inspection
A customer emailed me once with the subject line: "Quick question about my solar system." The question was: how many moons does our solar system have? I had to look it up. According to the International Astronomical Union's latest counts, the answer as of spring 2025 is somewhere north of 400. Saturn alone got a bunch of new ones recently, which is a fun fact you can use at parties.
But that wasn't the solar system we needed to talk about. He had an off-grid cabin with a Victron Energy inverter charger, and the battery bank was underperforming. The moons question was a detour. It's also a perfect example of what I call the blind spot problem: people spend time on interesting questions and miss the boring ones that actually break things.
I see that blind spot every day in my quality inspections.
What I do (and why it matters)
I'm the quality / brand compliance manager at a renewable energy distributor. My job is straightforward: no Victron Energy inverter charger and no Victron Energy charge controller leaves our warehouse without a full pass. I review roughly 200 unique items every month. Four years of that, and I can tell you the same three mistakes show up over and over. None of them are on a spec sheet. All of them are preventable. In 2024, I rejected about 11% of first deliveries. Usually small stuff. But it adds up.
Let's walk through the three biggest issues I've caught recently. You might recognize one of them.
The inverter charger with someone else's settings
First, the Victron Energy inverter charger issue. Most buyers pick a unit based on wattage and surge rating. That makes sense. But those numbers don't mean much if the firmware settings inside are wrong.
In our Q1 2024 audit, we flagged a batch of MultiPlus units. The boxes had the right specs. The model numbers matched the purchase order. But when we connected them to a test battery, several showed a charge voltage of 13.8V instead of 14.4V. That's a big deal for a 12V system: the battery would never fully charge.
Where did that come from? Someone had used the units in a previous install and changed the preset. When they were returned and restocked, nobody reset them. We shipped two units before we caught the pattern. The customer didn't notice immediately; the batteries just died a little faster every week.
That was a communication failure more than anything. The warehouse staff said: "They're new, they'll be fine." I heard: "Don't bother checking." I know better now. Even a new Victron Energy inverter charger is a computer plus a power stage. You wouldn't install a computer without checking the OS version. The inverter deserves the same respect.
We ended up rejecting 6% of that batch and made the vendor reset every unit at their cost. It took a day. But that sort of issue never shows up on a spec sheet—until your customer's inverter just stops charging properly. Now every MultiPlus gets a 30-second settings check. That one rework taught me more than any manual.
The charge controller with a loose screw
The second issue was on a Victron Energy charge controller. Actually, it's the issue that shames me the most because I almost skipped the check.
We had a 50-unit order for a community center. The controllers were SmartSolar MPPT 150/35s. Same model we've installed a hundred times. I was doing the final inspection, and I thought: "Do I really need to torque-check these terminals again? We've never had a problem."
The answer was: yes. Of course yes. That's the definition of overconfidence bias.
I tested one unit anyway. The thermal camera showed the positive DC terminal at 140°F after ten minutes at full load. That's warm. Not "melt your jacket" warm, but not "let it ship" warm either. I pulled the cover and found the screw in the main battery fuse holder was a quarter turn loose. Not missing. Not stripped. Just loose enough to create resistance.
We stopped the line, checked every one of the 50 controllers, and found four more with the same issue. It cost us a full day of rework. The fix took four seconds per screw.
The thermal image is still on my phone. It's a good reminder: I skipped a step that "never mattered," and the odds caught up with me. 5 minutes of verification beats 5 days of correction. That's not a slogan; that's a time log.
The solar module connector that cost us a field trip
The third issue is the one people hate hearing about because it's boring: solar module connectors.
Everyone asks about the controller and the inverter. Nobody asks about the little MC4 connectors that join the panels together. But those connectors are a hotspot for voltage drops. We tested a batch of aftermarket connectors that looked exactly like genuine MC4s. They measured a 1.1% voltage drop under load. That doesn't sound like much. In a 48V system, it's half a volt lost as heat. Over a long string, it's enough to make a charge controller behave oddly or trigger a shutdown.
The worst case was a field failure that cost us a $2,200 service call. A system was losing power at night. The battery was fine. The Victron Energy charge controller was fine. The problem was a connector between two panels: the crimp was 1mm too short. It had worked for months, then slowly started arcing. By the time we got there, the connector was charred.
It wasn't even a bad connector. It was just assembled by someone in a hurry. A 20-cent part. A $2,200 trip.
So when someone calls and asks, "do you have a solar controller near me?" I always ask what connectors they're using. That question gets more silence than anything else.
So, about those moons
Back to the moon question. The answer changes every year because astronomers keep finding more. But the real lesson from that email wasn't about moons. It was about distraction.
The customer's actual problem was that he had undersized battery cables and was losing 2% of his system's power as heat. The moons were a fun fact; the cable gauge was the fact he needed.
I've come to believe that every field issue I've caught boils down to the same pattern: someone skipped a check because the check seemed unnecessary. The moons were unnecessary. The torque check wasn't. The connector crimp check wasn't. The preset reset wasn't.
My checklist now has 12 points. It takes about 12 minutes per unit. One day of rework cost us more time than 250 standard inspections. That math is obvious if you bother to do it.
So the next time you're tempted to ask about something interesting, save it. Ask about the boring stuff too. Your solar system will thank you.