24v Panel --> 12/24v PWM Controller --> 12v battery??

[wlai]

Is the above arrangement workable?

I can get really inexpensive 24v panels, and was going to grab a cheap 12/24v PWM inverter ($15 eBay specials) and hook it up to a single 12v AGM.

It's for a small sailboat that doesn't have any electronics other than a few cabin lights, nav lights, and a depth sounder. It came with a 100wh AGM that was charged only occasionally when docked, but I'd like to have it be topped up automatically. To be honest even a 10w trickle charge panel could do the trick, but wanted to get my hands wet with solar and start learning with a cheap setup. Thanks.

 

[snoobler]

You want to put a 24V panel on a PWM controller connected to a 12V battery?

PWM controlled panels are essentially shorted to battery and forced to operate at a lower than optimal voltage, so the maximum output from the panel will be about 30-40% of rated.

Of greater concern is the 100Wh AGM battery. 100Wh/12V = 8.3Ah. You typically don't want to charge at a rate greater than 0.2C or 1.66A in this case, which would be a 12V panel at about 30W. You're likely going to charge the battery too fast and shorten its life if you go with a higher output panel.

 

[Forbisher]

Of greater concern is the 100Wh AGM battery. 100Wh/12V = 8.3Ah. You typically don't want to charge at a rate greater than 0.2C or 1.66A in this case, which would be a 12V panel at about 30W. You're likely going to charge the battery too fast and shorten its life if you go with a higher output panel.

He probably meant 100Ah AGM not Wh.

 

[Goombah111]

Is the above arrangement workable?

Saw your post on reddit. Glad you were able to figure it out. Best of luck to you