Here is an excellent article about comparing the real deal Solbian with genuine SunPower Cells vs the Chinese knock offs. Must read for anyone considering going this route if you want to make an informed decision.
Essentially there are a lot of panels that look like the SunPower Cells but they are not all made with the same quality controls and they don’t handle the bending as well. Articles like this is why we struggle with the decision to go with a lesser brand vs. the Solbians. In the end we went with Renogy semi-flex panels ordered from Amazon that were Prime eligible for free shipping. We paid $197 each for two 100 watt panels. More panels will be added in the future but these are the two to go on the bimini.
One thing my research pointed to was that testing the panel once you get them is imperative to getting good performance out of the array. On line I have read reports of people ordering two panels and getting one in excellent shape while the other had oxidation and damage. Others had received panels that looked the same but performed very different. So I did a thorough inspection of the panels when I got them. One thing I noticed right off the bat was that the connection on the Renogy panels, compared to the Solbians I had seen at the boat shows, were a little underwhelming. The Solbians have a nice junction box but the Renogy had a cheaper plastic connection filled with sealant to make it waterproof. I like the Solbian approach better but you get what you pay for.
After I was satisfied with the initial inspection, I moved on to testing the performance. It took a couple of weeks to finally get
decent enough weather to do the test. It was cold and very sunny when I set up the panels for testing. Using a saw horse I angled the panels towards the sun and ran a couple of tests. The open voltage readings (multimeter connected directly to the MC4 connectors for the panels) on the panels were 23.4 and 23.5 volts. Next I hooked them up to a Group 27 AGM battery we had for work. The battery had been depleted to roughly 50% state of charge. The negative lead for each panel was connected directly to the negative battery post. The positive leads went to a cheap “A/B” style switch I had for work stuff. The common side of the switch was connected to a multimeter positive lead and the negative lead was connected to the battery post. A second multimeter was connected to the battery to get voltage readings. This setup allowed me toggle between each panel and see if they were performing the same. (Sorry, its unlike me but I forgot to photo the setup.) For both panels I was getting 16.2 volts at the batter with a current of 6.3 amps. I let each panel run to the battery for about 15 minutes before recording the reading.
These results put my readings slightly above the I-V Curve published by Renogy. I wasn’t too surprised to out perform their curve because it was only 20 degrees F when I was doing the test. The published curve is for 77 degrees F. And since heat reduces the efficiency of the panels I expected to be on the high range of the curve, being just outside the curve gives me some hope to get close to the curve in a real world application.
Next step will be to mount the panels to the bimini and wire them up with the charge controller. Unfortunately that will have to wait another month or two. My Bride has been working to replace the window in the bimini that broke last year. That is complete and she has repaired some other areas as well. But we can’t put the bimini up to check the panel placement until we take down our winter biodome (aka clear shrink wrap). In the mean time I can work on installing the charge controller (I was able to get one of the last Rogue MPT-3048 charge controllers available thanks to Compass Marine) and getting the rest of the install ready.
In the meantime, onto to other projects on the Epic To-Do List. This weekend I will be changing the macerator pump. That will be a shitty job (pun intended).