How many solar watts should I get?
Thinking of investing in some portable solar panels but once again, I'm confused by the amount of product diversity out there. And my knowledge on the topic is minimal. :h So to understand what I'...
Forum Discussion
Solar Blvd is selling a 75 watt panel for $93.75 plus shipping and tax (link). This panel weighs 15 lbs. which would make it easy to handle and store.
To start with, I would advise buying two 75W panels and no controller. When I helped a fellow camper hook up his panel I used a standard 3 wire 50ft. 12 gauge extension cord. I then chopped a short cord in half and wired the female end to his battery and the male end to the panel. Since only two wires are needed you can tie the green and white wires together which gives you less resistance and thus less voltage drop. Connect black to positive and green/white to negative.
If you monitor your battery condition closely you can get by without a controller. Also it would be a good idea to unplug the panels at night to prevent possible discharge through the panels. Some panels have diodes to prevent this.
If this works well you then can think about a controller. The cheapest approach is a PWM controller. The most efficient and more costly would be the MPPT controller. With two panels you could connect them in series which would give you a nominal 24 volts (closer to 40 volt actual). This gives you less voltage drop between panels and controller. The MPPT controller knocks 24 volt down to the proper charging voltage.
To start with, I would advise buying two 75W panels and no controller. When I helped a fellow camper hook up his panel I used a standard 3 wire 50ft. 12 gauge extension cord. I then chopped a short cord in half and wired the female end to his battery and the male end to the panel. Since only two wires are needed you can tie the green and white wires together which gives you less resistance and thus less voltage drop. Connect black to positive and green/white to negative.
If you monitor your battery condition closely you can get by without a controller. Also it would be a good idea to unplug the panels at night to prevent possible discharge through the panels. Some panels have diodes to prevent this.
If this works well you then can think about a controller. The cheapest approach is a PWM controller. The most efficient and more costly would be the MPPT controller. With two panels you could connect them in series which would give you a nominal 24 volts (closer to 40 volt actual). This gives you less voltage drop between panels and controller. The MPPT controller knocks 24 volt down to the proper charging voltage.
