I was at the local tender center this weekend and spotted a good looking portable solar panel. It was a BP solar 150W, made in USA, polly panel with the usual cheap PWM regulator stuck on the back and a longish cable with an anderson style plug. Quite a lot of lookers while I was there. A bargain at $50 reserve and sold for $90 + expenses. At first site someone should be happy BUT......
The panel was a good quality one but is actually a 24V nominal panel with a Vmp of 34.5V and Imp of 4.4A. Good if you want a portable panel for a 24V system and I hope the buyer wanted that. But if they have a 12V system then they will be disappointed. Why is that you ask. Well they will only get the 4.4 amp current no matter what and so at the max battery voltage of 14.4v they will be getting only 63 watts. Possibly be good in very low sun though. Another punter saying this solar is **** I dunno why we bother
The best answer in this case is to fit a genuine MPPT regulator and 'hey presto' that 4.4 A will jump up to 8-10 A in good sun. Some panels can be rewired as two 12V halves in the junction box but this one could not be modified easily.
So just a cautionary tale for new players to learn from Good quality will not help if it is the wrong panel for your job !!
Jaahn
-- Edited by Jaahn on Sunday 31st of March 2019 09:03:21 PM
Ages back one of the on line solar mobs were selling 24v seconds panels for 50c/watt. I modified them to 12v panels by cutting the joiner strip at the bottom of the panel and soldering a second set of wires to those ends. This way the negative original cable at the top and the new cable at the end ribbon on that side of the panel became 12v positive. The other end of the now cut ribbon became a negative and the original positive cable was now 12v positive rather than 12v negative.
I mounted 4 of these modified panels on the roof of my Mazda T3500 and time gave me 750w @ 12v for $375 back when solar was still around $1.50/watt. That was probably 6 yrs ago or maybe more, they still work fine, so with a bit of hands on work, bargains can still be found.
T1 Terry
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Another punter saying this solar is **** I dunno why we bother 
