Greeting from the solar stone age. I built tiny 100 watt 12 volt system in 1985 and have been using it ever since as sole source of juice. Now expanding to 400 watts. I'm hoping to use the same wire I installed way back: 10 gauge copper running 50 feet to six golf cart batteries wired up as 12 volt bank. Can I successfully do the expansion by wiring the panels to pump out 24 volts into a new controler, the new fangled kind, mmpt, the kind that takes in 24 volts and puts out 12 for the battery? Or is there another better way to do it? Also, any controler recomendations? thanks, Nick
expanding tiny system 100 watts up to 400
- Thread starter nick20
- Start date
Rider
Solar Addict
Basically, yes. 400w at 24VDC is about 17A, so the 10 gauge wire should be fine, but stranded is preferable. Take a look at Will's vids on solar controllers, he recommends a few like Victron, EPever, and a couple more. A 30-40 Amp or MPPT would be fine.
D
Deleted member 783
Guest
Wow, your 1985 components are still working? Surely you've replaced the batteries a couple times? I hope my gear lasts that long.
yes the two 50 watt Arco brand (later became Siemens) panels are now charging rolling power cart with battery/inverter on bicycle wheels. New expanded system has four new Renogy 100 watters. The old Siemens were about $320 each. I'm on 4th set of batteries. First two sets were each six golf cart 6 volt wired up as 12 v bank. These were all used and cost $15 each. Third bank consisted of four 12 volt marine deep cycles which were free. I sold all these, when lead was high and got back more money than I'd spent on them. Now running 4th set, again golf cart batteries. Having a big bank and small amount of load really lets the lead batteries last.
Does anybody know if these mppt controlers will accept 48 volts from the four panels and then step it down to charge 12 volt bank? Or is the 24 volt panel array charging mppt 40 amp controler a good way to go for charging 12 volt bank?
Does anybody know if these mppt controlers will accept 48 volts from the four panels and then step it down to charge 12 volt bank? Or is the 24 volt panel array charging mppt 40 amp controler a good way to go for charging 12 volt bank?
Rider
Solar Addict
Most of the mppt controllers accept up to 140VDC. Each one is a little different, so you need to look at the specs to make the right choice based on your panel config.
Thanks everyone for your replies. I'm wondering now about DC fuses and what is better about various DC fuses compared to car fuses. Don't all the 30 amp fuses blow at 31 amps? And, when I wire up my four 100 watt 12 volt, 5 amp panels in series to get 48 volts heading down 10 gauge wire 50 feet to the 40 amp mppt controler, the current in the wire will be 5 amps, right? And now what fuse should I use in the positive 10 gauge wire, a six amp? And the fuse can be located on the board right near the controler? And finally, what fuse in the positive cable (l've got 0 gauge mono or 2 gauge stranded to choose from) running 12 volts from controler down to 12 volt battery bank 6 feet away? 30 amps? And again, what exact type of fuse? Thanks for your attention and any thoughts.
offgriddle
"FOREVER BEGINNING"
There are many MPPT controllers on the market that either automatically sense, or can be configured for 12, 24, 36 or 48 VDC input. I am happy with my recent decision to upgrade from the Pulse With Modulation charge controller to a more modern and more efficient Maximum Power Point Tracking solar charge controller. I also wired my twelve volt panels in series to produce 24 volts because higher voltage transports more efficiently over wires, (see my simple diagram). I also replaced my older technology lead acid batteries with lifepo batteries, which deliver amazing performance, however, the battery change was the most expensive part of my upgrade. Upgrading to an MPPT controller and transmitting your voltage at 24 vdc alone will yield improvements and in case your not ready or you do not wish to change your batteries, MPPT controllers can be configured to properly charge and maintain caveperson lead acid batteries, (of course check controller specs. to confirm before you purchase). Have the fun, peace.
