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Advice on sizing a solar system for a van build

Majten

New Member
Joined
May 8, 2021
Messages
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Hi,

So we're building van that will be used for year around living, mostly in warmer climates. I've been doing a lot of research for the solar system and landed on using the DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT from Renogy, as it seems to be an easily installed and intuitive option for someone who doesn't have that much experience.

However, I've seen in several places that it's recommended to use this with a solar array of max. 400W (instead of the rated max. 660W) and understand that this is due to the low max. input solar voltage of 25V of the Renogy, which requires you to install your panels in parallell and have high amperage. The issue is that I'm not sure 400W will fully cover our need, and as we'll be working remotely and I really want to make sure we have enough power. It's not that big of a difference, but bumping it up to 500W-550W would probably be preferable. So, my question is really related to that. What would it take to be able to connect say 3 x 175W panels to the battery charger? Thicker wires and adapters? Would it be worth it, or should I look into getting an MPPT and a charger separately instead?

Thanks a lot,
M
 
Having a solar controller capable of accepting higher panel volts than the 25v of the DCC50S would allow you to use the more cost effective large, 300 watts plus, panels that have a higher working voltage.
Having separate units gives a degree of redundancy in case of failure. There are mixed reviews on Renogy products that you may wish to consider, there are number of discussions regarding the DCC50S on the forum and reviews on YouTube.

Using 600 watts of lower voltage panels feeding the DCC50S in parallel is not a huge problem with just over 30A into the controller. The usual MC4 connectors are rated at 20A max so it would be advisable making the parallel connection on buss bars ( rather than using the 20A limited MC4 parallel converter, this current limit is the major thinking behind the 400 watt limit), and feed heavy gauge cable from this point to the controller.

Reliability of equipment could be important if your travels put you in a position where replacements are not easily available.

Solar panels themselves (not the flexible type) are very reliable and should a solar controller fail, there are workarounds to use the panels directly to charge the battery ( with manual control of the charging process). There are similar procedures in an emergency to charge direct from the alternator.

I suggest you continue with your plans to use the DCC50S with 175 w panels at this stage, since as you have said, its a less costly and complex method of getting a usable system compared to alternatives. If your requirements change in the future, that need an alternative solar controller, you still have a alternator based charger rated at 50A with the DCC50S.

Mike
 
Having a solar controller capable of accepting higher panel volts than the 25v of the DCC50S would allow you to use the more cost effective large, 300 watts plus, panels that have a higher working voltage.
Having separate units gives a degree of redundancy in case of failure. There are mixed reviews on Renogy products that you may wish to consider, there are number of discussions regarding the DCC50S on the forum and reviews on YouTube.

Using 600 watts of lower voltage panels feeding the DCC50S in parallel is not a huge problem with just over 30A into the controller. The usual MC4 connectors are rated at 20A max so it would be advisable making the parallel connection on buss bars ( rather than using the 20A limited MC4 parallel converter, this current limit is the major thinking behind the 400 watt limit), and feed heavy gauge cable from this point to the controller.

Reliability of equipment could be important if your travels put you in a position where replacements are not easily available.

Solar panels themselves (not the flexible type) are very reliable and should a solar controller fail, there are workarounds to use the panels directly to charge the battery ( with manual control of the charging process). There are similar procedures in an emergency to charge direct from the alternator.

I suggest you continue with your plans to use the DCC50S with 175 w panels at this stage, since as you have said, its a less costly and complex method of getting a usable system compared to alternatives. If your requirements change in the future, that need an alternative solar controller, you still have a alternator based charger rated at 50A with the DCC50S.

Mike
Thanks a lot for your reply, Mike! That really answers my question. I think I'll stick with the DCC50S for now then and go for the 175W panels connected on buss bars.
 
I've been trying to figure out what kind of combination of solar panels I should be using for my setup, and it seems like either five or six 100W panels from Renogy would be my best option financially, instead of 3 x 175W like I mentioned in my original post. I'm having trouble working out how I would connect this setup to my DCC50S though, taking the MC4 limitations into account. Could anyone perhaps elaborate on this and give me a hand? Like using a busbar, as Mike suggested above?

Thanks!
 
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