What I've learnt about the solar panel over the past week

As mentioned in my last post, the weather has been terrible for testing the solar panel.

We've had enough rain over the past few days that various parts of Birmingham have flooded, and my own route into town, via one of the tunnels under the ring road, required some parkour to traverse without getting my feet wet.

But interspersed among all the rain we have been lucky enough to have a few sunny periods. So in my quest to see the battery get fully charged, during every such period I set-up the solar panel - which in turn allowed me to make some interesting discoveries about it.

First off, it appears that even the smallest amount of shadow on the panel has quite a profound effect on the amount of energy it can produce. My balcony has a metal railing with shadow-casting vertical bars that span down to the floor. The simple act of moving the panel back a few inches, out of the shadows cast by the bars, doubled the reading on the multimeter.

Second, I think I had the cheap multimeter on the wrong setting. I discovered this when I temporarily replaced it with my new one (which is autoranging) - the numbers showing across the two devices matched, but the location of the decimal point didn't. Based on this, I've moved the dial on the cheap one to the 20m setting, and now they're in line with each other.

Third, unless I'm totally misunderstood the readings from the multimeter, it seems that the maximum output the panel can produce is 0.5 amps. This reading was taken during a break in the clouds, with the panel sitting in direct sunlight. The fact that I think they're amps is based on the output of the new multimeter, despite being registered on the old one. I'm hoping to confirm this reading the next time we've got some sun.

Finally, after a week of the weather alternating between sun and rain, the "full" LED on the charge controller lit up. I did a jump for joy and immediately plugged in Android tablet into it to charge.

That's all for now. I'm away this weekend, but with some luck, we'll have some sun next week, and I'll find some money for the next project.


Update: a couple hours after I initially published this post we had a break in the clouds. This resulted in a lot of glorious sunlight reaching the earth, which I took as an opportunity to properly break in the new multimeter. I did this by hooking it into the system, then holding the panel out over the ledge of my balcony and pointed it directly at the sun.

The result was a maximum reading of 1.5 amps.

This is the highest reading I've ever seen produced by the panel and knocks the previous readings out of the park. I think the difference was caused by a better positioning of the panel, making it face the sun directly, rather than at an angle like it was before. I'll experiment more in the coming weeks.