Getting solar power into my truck

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I have a simple solar panel, that i plan on using to keep my battery topped off while away from AC power.

I have a battery in my camper shell storage. Now I open a side window on the shell to bring an AC cord in to charge the battery. I don't foresee needing a full-time panel on the roof, rather I plan to set up a solar panel on the roof or on the ground to follow the sun when needed. How and where should I put an outlet to be able to bring power into the truck? Attached is a photo of my truck shell, the battery power department is in the left corner of the photo.

I just got a crimper and some MC-4 connectors I may be running as long as a 50-foot power cord. What type of wire should I use, and what gauge?

 

[dreadlocks]

Tinned, Marine Gauge Wire.. jacketed.. something like this: https://www.ebay.com/itm/Marine-Gra...per-USA-Made-AWG-Gauge-All-Sizes/132261116037

I put anderson powerpoles on everything, made 4x25ft lengths and stuffed em all on a reel.. I used 12awg, but I have high voltage panel (60v) so wire gauge was not really critical, you might wanna do 8-10awg on 100ft w/a 18v panel.. put the controller in the truck, run the higher voltage on the long run and not the 12v like if controller was w/the panel.

 

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I think I am going to need 8 gauge to offset low power panels. Because the ebay link is out of 8 gauge, I was thinking of buying these cables.

https://www.amazon.com/gp/product/B07NH9HKRR/ref=ox_sc_act_title_1?smid=A3CCBPRC9BFHC9&psc=1

Then making a pigtail from MC-4 to Anderson connector.

Any suggestions on where to mount the APP inlet on a truck bed?

When you say you have 4x25' cords, do you use them together as needed? Add all 4 to get 100 feet or just use one to get 25 feet?

 

[dreadlocks]

They have other sellers of that type of cable, thats just whom I bought mine from so I suggested it.. I wouldent get individual wire strings, 100ft of that would end up in a big christmas light ball of knots.

I only use whats needed, if I put it right by the trailer.. 25ft of wire on it.. if I move it far away.. I use whats required and no more, for minimal voltage drop.

I would just put the plug inside somewhere and run it through that window personally..

What kinda panels you using? how many? If you have two 18v panels you can put em in series and make em 36v..

 

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Right now I have this panel I "stole" stole off my sailboat. My power needs are very minimal. I end up using a lot of things with rechargeable batteries. I go 3 days without barely touching my SOC on my 24 series deep cycle. The plan is to use this 50watt panel for now. I will add a small panel for my boat to keep the power topped off when not onboard. This 50W panel will travel with me from truck to boat when needed. I do want to design this system with a future panel upgrade in mind.

I just burned a hole in my credit card with orders from Amazon, Powerwerx and Home Depot. I have an MPPT controller coming, 30 foot 8 gauge MC-4 cables, Anderson Power Pole adapters and hopefully everything else needed to wire up some solar for the truck on the way.

 

[dwh]

You won't need #8 for a 50w panel. A 50' or 100' roll of #12 landscape cable would be overkill.


https://www.homedepot.com/s/low%20voltage%20landscape%20wire?searchtype=suggest&NCNI-5


Best thing about that stuff is it's got a tough insulation, so stepping on it or dragging it over rocks and sand won't hurt it much if at all.

 

[dreadlocks]

100ft 12awg 17.5v @ 3.17A = 5.75% drop (~16.5v at controller) (~3W loss)
100ft 10awg 17.5v @ 3.17A = 3.62% drop (~16.9v at controller) (~2W loss)
100ft 8awg 17.5v @ 3.17A = 2.28% drop (~17.1v at controller) (~1W loss)

The losses on a 50w panel are so small, yeah 12awg is fine despite the 5% drop.. but you need to check that 16.5v is suitable for firing up your controller.. many mppts require a minimum input voltage over output voltage before they can fire up.. PWM's I dont think care as long as its > output voltage.

 

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Great wire, but its going to be miserable stuff to laydown for portable solar array.
Notice, its ’specs, 7 strand copper with XPLE insulation. (Each strand is about 18AWG. XPLE is crosslink polyethylene, stiff plastic. Much like PEX waterpipe)
That stuff will handle like a coiled spring or concertina wire.
It will work, but nobody will be happy laying it out and coiling up again, never mind tripping over its loops.

Too late it's on the way. Worse case scenario I can use the cable to create something more permanent mounted on my roof when I replace it with something more workable.

You won't need #8 for a 50w panel. A 50' or 100' roll of #12 landscape cable would be overkill.

This is the panel I am using now, I like to overbuild for future growth potential. I keep my power use to a minimum but would consider a chest fridge freezer down the road, so may need more panels someday.

 

[dwh]

but you need to check that 16.5v is suitable for firing up your controller.. many mppts require a minimum input voltage over output voltage before they can fire up..

At that point there would be no load, so no voltage drop.

PWM's I dont think care as long as its > output voltage.

PWMs don't actually have an output voltage. When the switch is closed and the PV is connected to the battery, the PV operates at battery voltage.

 

[dwh]

(~16.5v at controller)

And...that's a misconception. Voltage doesn't drop from one end to the other. A circuit is a circle, and a circle has no ends. Voltage drops around the entire loop.

 

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The losses on a 50w panel are so small, yeah 12awg is fine despite the 5% drop.. but you need to check that 16.5v is suitable for firing up your controller.. many mppts require a minimum input voltage over output voltage before they can fire up.. PWM's I dont think care as long as its > output voltage.

I have a 100 V 20 A Victron MPPT charger coming. If the panel does not put enough voltage to start it up I will look at a large folding panel to use.

The question I should have asked before ordering the charge controller is.... Is a 100V 20A charger enough to future proof my needs? Except for a refrigerator my electrical needs are minimal. I would think a set of panels equalling 200Watts would be all I will ever need at least for my truck.

 

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And...that's a misconception. Voltage doesn't drop from one end to the other. A circuit is a circle, and a circle has no ends. Voltage drops around the entire loop.

Do you mean a 100 foot run needs to be computed as 200 feet of wire?

 

[dwh]

Do you mean a 100 foot run needs to be computed as 200 feet of wire?

No, I mean the voltage at the panel, and at the charge controller, and at all points in between...is the same.

You can fool yourself with a meter. Put the probes at the charge controller and see say 16v, and then at the solar panel and see say 18v. Makes you think there's a 2v drop from one end to the other.

That's wrong; there are no ends.

When you see that 18v at the panel, you are actually bypassing the charging circuit and reading the full potential of the panel, not the voltage of the charging circuit.

The charging circuit which is actually at 16v all the way around.

 

[dwh]

20a (Victron max) x 14.8v (or whatever you bulk the battery to) = 296w.

So yea, the 100|20 can handle 200w no problem.

 

[dwh]

Now, what actually happens is the MPPT is going to sweep - raise and lower the operating voltage of the solar circuit - to find the sweet spot where it gets the most watts (the panel's Vmp right this minute).

So it doesn't actually matter if the wiring theoretically causes say a 2v drop under load. The MPPT will still find the operating voltage to get the most watts.

So you can calculate the voltage drop and assume the solar loop voltage will be 16v, but if Vmp is 18v right this minute, the MPPT will be operating the solar loop at 18v.

No matter if you use #8 or #16 wire.