Sizing Solar Cells for Couple Full-time Boondocking

[SendIt]

There’s no easy way to mount a fourth.

Also, All panels would be flat and the roof is somewhat curved, so all three will never be incident to the sun.

 

[SendIt]

I’ll check back in with specs tomorrow

 

[SendIt]

Ok, I finally got my specs: https://a1solarstore.com/var/attachments/product/17086/Phono_Solar_PS545M6H-24_TH_Data_Sheet.pdf (545 watt variant)

Isc: 13.75A
Voc: 45.45v

So looks like I’m gonna wire them parallel into the 150/100…

Would be nice if I could add a fourth and do two strings of two, but the mounting would be a major pain to get height I need over the features on the roof.

 

[HRTKD]

In series you would have less than 15 volts of buffer before you exceed the Max PV Input Voltage, something you never want to do. If you use the Victron MPPT calculator and plug in the temperature coefficient of you panels and your lowest temperature, you may find that series is OK. The calculator will tell you if it's OK or not.

 

[SendIt]

Is it safe to put a shut off switch between the solar charge controller and the battery?

I think I remember hearing that could damage the charger if it’s hooked up to panels with no output, but wanted to double check.

 

[RoadTurtle]

Is it safe to put a shut off switch between the solar charge controller and the battery?

I think I remember hearing that could damage the charger if it’s hooked up to panels with no output, but wanted to double check.

why do you need a shut off between SCC and BUSS BAR (not battery)? If you shut off inbound solar energy, there's not reason for a separate shut off

 

[zulu]

On solar my advise (espically if not tilting), is to put as much as you can on the roof.

x2

 

[HRTKD]

why do you need a shut off between SCC and BUSS BAR (not battery)? If you shut off inbound solar energy, there's not reason for a separate shut off

For some, covering panels may not be an easy thing to do. MC4 connectors are not to be disconnected under a load. A dual pole breaker is an easy and safe way to cut off PV power into the solar charge controller.

 

[Rednecktek]

For some, covering panels may not be an easy thing to do. MC4 connectors are not to be disconnected under a load. A dual pole breaker is an easy and safe way to cut off PV power into the solar charge controller.

Right, but usually it's from the panels to the SCC, not the SCC to the battery. There's no reason you can't and it would provide protection between the SCC output and the battery, but not necessarily needed.

 

[SendIt]

I found some inexpensive breakers and went with that option.

 

[HRTKD]

I hate to say this, but I think those are AC breakers. You need DC breakers. The Chtaixi DZ47N-63 breaker has an AC rating and no DC rating.

 

[Rednecktek]

I hate to say this, but I think those are AC breakers. You need DC breakers. The Chtaixi DZ47N-63 breaker has an AC rating and no DC rating.

Correct, at least according to the Amazon posting they're AC only.

 

[SendIt]

Oh man, good catch!

 

[ill.behavior]

If you are going full-time in that rig, ( and don’t think you will change rigs), I would make a frame of aluminum and have the roof completely covered. That way you have panels over the vents and A/C’s. This will keep the sun off the roof (cooler and no sun damage) and you can use larger (cheaper per watt) panels.

This is awesome in theory, but my 37' rig is already 13.25" tall and I don't think I could add any additional height without creating my own atmosphere

 

[SendIt]

I ended up replacing the breakers with DC. Thanks everyone for the help! Here's a link to the final design:

Designing Victron System for Keystone RV Travel Trailer

99% of trailers with electric brakes only have a mini sla battery that just charges off the 7 pin including those with a power tongue jack. Not travel trailers but just everyday flat or enclosed trailers. If your chassis battery isn't lasting more than a couple weeks you have something else...

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