I'm back in from playing with the Nebo solar panels. My first effort was just to ensure the "used" one actually worked. I think so.

I had some problems with the MC4 connectors from the first panel, so I bought a couple other ones with barrel connectors and adapters. They had oppositely colored wires on the male and female connectors, so I figured at least one of them would have the right polarity.

Nope. Wire color has nothing to do with polarity in these products. The two latest ones each included a strip of paper with a warning to check polarity as different solar panel manufacturers do things differently. So do different cable manufacturers.

What can I say? This is my first rodeo.

What I can say for sure is that center is positive on the barrel connector, shell is negative on the Nebo 100 watt solar panel. And in direct current, conventionally, red is positive, black is negative. It was astonishing to me how confusing that could get dealing with different connectors, and different colored wires that had nothing to do with polarity.

What I can also say is that each of the MC4 to barrel plug connectors had the male MC4 plug (Which is itself a matter of some confusion or debate. At the moment, I'm convinced that the gender of the connector corresponds to the electrical part of the connection, not the plastic shell.) wired to the positive center. The Bluetti XT60 to MC4 cable also had the male MC4 connector wired to the positive connector in the XT60. So maybe that's a convention of some kind. In any event, the positive voltage from the panel was present at the same type (gender) of connector as the positive voltage input to the AC70 (Which has the XT60 connector. Confused yet?), which means I couldn't connect them without reversing the polarity, which could be bad ("Don't cross the streams!"), or just result in not charging. (Luckily, it's not "bad" since I did connect them that way when I was futzing around the first time a couple of days ago. I think Bluetti designed the product such that it has reverse polarity protection, probably a diode. Lucky me.)

Anyway it's a good thing I bought a crimper and some extra connectors. (Note to self: Buy a better wire stripper.)

So I swapped the MC4 connectors on one of the cables, and let me add quickly that it's a really good thing I could look at the color of the insulation in the discarded connector, because I immediately forgot which one was which and, naturally, I cut them both off at the same time.

So, after taking a lot of deep breaths, I got the connectors swapped and went out to try again.

Success. I'm getting about 75 watts from the first panel and 55 watts from the "used" one. I suspect it's a matter of them not being oriented exactly the same. There's a little gimmick device you can buy to check that too, but I was more or less relying on their shadows. But looking at them after swapping the cables around, I could see the original one I bought was a few degrees off from the used one.

Both were putting out roughly the same voltage, so I'm pretty sure it's fine, but I'll play with it some more.

Well, I'm going to declare victory and award myself a meritorious afternoon off.

And take a nap.

Originally posted at Nice Marmot 13:26 Saturday, 13 April 2024