BAC Forum
General Boards => Technical Support => Topic started by: Ryan Sneller on April 29, 2016, 06:08:04 PM
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New member here, first post too! so here goes...
We have a 2008 PT without factory solar, id like to install solar on it. I have a 250w solar panel that I had lying around that wasn't used on another project. Problem is..... its 24v output. My good quality Charge Controller I have purchased it 24/12 v auto sense on the input side. I have also purchased (way cheaper than a new solar panel) a DC DC step down converter to take my 24v to 12. Now here is my question, does anyone see any issues with installing it (dc dc converter) on the above side between the panel and the solar controller or should i install it on the lower side between the controller and the batts. In my pea brain I could do either since the controller/charger is auto sense 12/24 as mentioned and I would assume it would output the same V as is inputted into it, just gotta get that 24 to 12 before it hits the batts. I just thought id get another opinion or two or six. Thanks Guys!
Ryan
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Ryan,
I would convert to 12V as soon as you can, that is before the charge controller. There are slightly less losses at 24V then at 12V regarding wire losses but that is only important if there are long wiring runs or if the wire gauge you are using is limited in some way and not adequate. I say convert early in the chain as possible because I think it will add another layer of protection from ever getting 24V or some other odd voltage as an output to the battery bank if something was to fail. That could be messy. I would also check the conversion losses of the DC to DC converter and see that it is not consuming a significant portion of the solar panel output. You have to overcome those losses with the panel quantity and configuration. I would run this whole set up a few days on the ground with a 12V battery with some load I could vary on it. "Burn in" this set up and see that you have consistent and sustainable results. If something does not hold up or is not working as you expect, better that happens off the coach.
Later Ed
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Thanks Ed! That's the info I was looking for.
Ryan
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Says its 85% efficient.
Ryan
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Ryan,
That means 15% of the energy gets turned into heat so be sure in your install to plan on a good open space for mounting, ventilated if needed, to get rid of the heat. When you are testing all this on the ground you can get a sense of how warm the converter gets and plan accordingly. It may be that with the output of the panel being low amps that even with 15% loss the converter remains quite cool.
Later Ed
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Hello, Ryan! I too have a 2008 PT without factory installed solar. I also would l8ke to install solar. Mt question is « Where did you run the wiring? I assume you mounted the panel on the roof, and have wiring to charger controller. I’m at a loss to find a route from the roof to the battery compartment. Any advise would be appreciated
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I have a 10 Watt panel which is supposed to charge the chassis batteries. The wire is broken somewhere inside the coach so I am also looking for another route. I am thinking of running it down through the vent opening for the fridge, thence down to the storage bays and then back to the battery compartment.