I'm working on rewiring my solar setup on my bus, which consists of five 100-watt panels connected in parallel. These are older BP panels, and when I test them individually with a multimeter, they're generating between five to nine amps each. However, once I connect them together, the total output drops to about 6 amps, despite being in full sunlight. I've confirmed good output from each panel, but it seems like there's a significant drop at the junction point before it reaches my controller. I'm still learning, and it's a DIY project, so I'm looking for some help to figure out what's going wrong. I'm using two 100 amp-hour Renogy batteries and a 30 amp Victron controller/charger, but it looks like I'm losing power in the wiring itself. Any advice would be greatly appreciated!
2 Answers
It sounds like you might have an issue with your connections, especially at the junction point. If all the individual panels are showing good amperage, but it drops when they meet at the bus bars, there could be a problem with the connectors or the bus bars themselves. Make sure they’re clean and securely connected. Also, check if the bus bars are sized appropriately for the total current you're trying to draw. Sometimes, insufficient gauge wire can create resistance that leads to a drop in current. You might want to measure right at the bus bars to see if the problem persists there.
You mentioned the panels are wired in parallel correctly, which is great. But have you double-checked the total output at your solar charge controller? Try covering the panels partially to see how it affects the amperage. If with all panels exposed you’re only seeing 6 amps, it may indicate the batteries are almost fully charged, causing the current to taper. Understanding the load on your batteries also helps, as a nearly full battery can limit incoming current. And yeah, be sure your multimeter is working right—sometimes it can be a faulty reading.