Solar for my van - Checking my shopping list and wire questions?

[zuren]

I think I've reached the point where I want to mount solar to the Thule rack on my van for extended trips and the infrequent power outage at home. I just want a review of my shopping list and thoughts.

I have only performed rough calculations but based on my reading, the couple LED lights I have and no big draw items (van is setup as an ultralight/weekender campervan), a 60w panel is overkill for what I have and the way I use it. The house battery is an isolated Diehard Platium Group 31M.

This is what I'm considering for a very simple, reliable, safe and expandable setup. I'm hoping those who know solar better than I can check my work:

- one 60w Solar Cynery panel
- Morningstar Sunsaver SS-10 charge controller
- Wires from panel to controller (type, awg???)
- Wires from controller to battey (battery cable, 4awg)
- Quick disconnect between panel and controller (???)

Ideally, I would want to be able to disconnect the panel and store it inside the van between trips. I'm considering the 10a controller rather than the 6a in the event I want to expand to a 2nd panel.

My biggest unknown is the wires from the panel to the controller. I'm looking at different sites with kits that have cables that I'm not certain I need, in lengths I absolutely wouldn't need. One these kits is the 95w Snapper. There is wire with MC4 connectors, "tray cable", etc. I'm drawing my info and choices from www.solarblvd.com.

I'm trying to get an understanding of cables with male/female MC4 connectors. Some places list them for panel-to-panel connections and others seem to suggest that it can go from panel to controller (cutting them). Does it matter? It looks like tray cable (8awg) could be run from a single panel to the controller but I would have to wire in a disconnect. Wires from the controller to battery look to be straight forward.

I plan to speak to a sales rep at Solarblvd but want to be educated on my choices so I don't get talked into something I don't need or wouldn't be happy with.

Thanks!

 

[wirenut]

Even though a 60 watt panel is more than you need it may be no more money to go to a larger one. The larger a panel you buy the cheaper it gets on a watts/dollar basis. Almost all cables with MC4 connectors are 10 AWG which should be fine for your usage. I would get one cable with a male on one end a female on the other end that is twice as long as you need. You cut the cable in the middle and there's your two wires.
The charge controller you list will do the job but doesn't give you a volt or amp meter. A Morningstar PS-15 would give you that but it is more money.
The MC4s will give you a quick disconnect between the panel and controller. Just don't disconnect them under load.
I wouldn't remove the panel. They're pretty durable. Leaving it on the van will allow it to keep your battery ready to go all the time.

 

[zuren]

Even though a 60 watt panel is more than you need it may be no more money to go to a larger one. The larger a panel you buy the cheaper it gets on a watts/dollar basis. Almost all cables with MC4 connectors are 10 AWG which should be fine for your usage. I would get one cable with a male on one end a female on the other end that is twice as long as you need. You cut the cable in the middle and there's your two wires.
The charge controller you list will do the job but doesn't give you a volt or amp meter. A Morningstar PS-15 would give you that but it is more money.
The MC4s will give you a quick disconnect between the panel and controller. Just don't disconnect them under load.
I wouldn't remove the panel. They're pretty durable. Leaving it on the van will allow it to keep your battery ready to go all the time.

Is this the controller you are talking about? - Morningstar PS-15M


The Solar Cynergy 60w or 80w fit the space I have perfectly. The number of watts/dollar are the same so, by my estimation, it boils down to my needs and the money I want to spend. Although, as the panel ages, the decline on larger panel will be less noticeable that starting with a smaller one...

 

[wirenut]

Yes, that's the controller I was talking about. I guess I forgot the M. It's basically the same circuitry as the controller you listed but gives you the metering which is nice to have.

 

[dwh]

You won't need #4 from the controller to the battery with that PWM controller.

The amperage from the controller to the battery won't be more than the amperage from the PV to the controller.

So if you use #10 from the PV to the controller, you can use #10 from the controller to the battery.


If you used an MPPT controller, then the amperage on the output side could be more than the amperage on the input side, but that won't happen with a PWM.


Standard practice is to do what wirenut recommended - get one long MC4 extension cable (male on one end, female on the other) and cut it in half.

But, if you want to make it disconnectable, you can buy a short MC4 extension and cut it in half, and splice the two ends to a twist-lock connector and use a #10 contractor's twist-lock extension cord. That's basically the same as "10/3 SJO Cord", but yellow. You can usually find 10/3 SJO by the foot at Home Depot.

Just make sure that the connector at the PV is female - you don't want hot live connector tips sticking out where they can bite you when the PV is in the sun. You would use a male at the controller.

Like this: controller->>-extension cord->>-PV



Also, MC4s are not really quick disconnects - they require a special set of tools:

http://www.solar-electric.com/ditoformc4co.html