How Many Solar Panels Can I Install?

[Desiday]

I have a 2015 Newmar Dutch Star that is prewired for solar. It was prewired with 10 gauge wire. How many 100W panels can I comfortably install using a MPPT controller? How much "juice" would that provide my 8-12volt house batteries? Would it be a big help?

[TravelSolo]

Originally Posted by Desiday

I have a 2015 Newmar Dutch Star that is prewired for solar. It was prewired with 10 gauge wire. How many 100W panels can I comfortably install using a MPPT controller? How much "juice" would that provide my 8-12volt house batteries? Would it be a big help?

Depends on how you wire the panels, their expected output for the climates you are expecting them to see sun (they are temp sensitive) and how many panels you can fit/afford/need/want.

I run four 100W Rich Solar panels in parallel to a 40A MPPT controller. There are various MPPT controllers on the market that will handle different voltage and amperage inputs so you need to size according to the power needs you have and what you can fit on the roof and afford.

[Desiday]

Originally Posted by TravelSolo

Depends on how you wire the panels, their expected output for the climates you are expecting them to see sun (they are temp sensitive) and how many panels you can fit/afford/need/want.

I run four 100W Rich Solar panels in parallel to a 40A MPPT controller. There are various MPPT controllers on the market that will handle different voltage and amperage inputs so you need to size according to the power needs you have and what you can fit on the roof and afford.

Is this using a 10 gauge wire?

[TravelSolo]

Originally Posted by Desiday

Is this using a 10 gauge wire?

From panels to controller is 10awg since my max amps at coldest temps from the 4 panels is 28amps. From controller to batteries is 6awg

[Rocketman3]

The 10 ga wire will handle 30 amps of current.

My 200watt Hightech panels can produce 9.5 amps - so you could run three in parallel for 600 watt array.

You can increase the amount of panels by running them in series ( this increases voltage). You could run 6 panels in a 2s3p or a 3s2p arraignment for 1200watts of power. You will need a mppt like the Victron 250/85.

If you have the roof space - You could probably get eight 200watt panels 4s2p with a Victron 150/100 - 1600watts on the roof - but the controller would clip it to 1450 watts when you have perfect conditions - that’s all through a 10 gauge cable.

Now how many panels do you want/need and can fit.

The 10 gauge cable is just one item you will need to design around.

The cable from the mppt to the batteries will need to be MUCH bigger.

After posting I saw you wanted 100watt panels all the calculations are the same - just twice as many panels.

[astrocamper]

My Artic Fox 22G was prewired for solar to the roof but I didn't make use of the wire for solar. I removed the small Zamp controller and used that 8 AWG cable for other purposes such as powering my audio, TV inverter and some 12 volt/USB outlets.

I put 2 pair of 6 AWG cables from a roof junction box to my pass through storage area where my DC bus bars and inverter are located. I have 1440 watts of solar on the roof using three 300 watt and three 180 watt panels going to two MPPT controllers. I have 640 watts from four thin flexible portable panels mounted to polycarbonite twinwall for lightweight stiffness running to another MPPT controller. I use the portable panels only in the hottest months when running my air conditioner on the inverter/charger while camping off the grid.

[SteveJ.]

Originally Posted by Desiday

I have a 2015 Newmar Dutch Star that is prewired for solar. It was prewired with 10 gauge wire. How many 100W panels can I comfortably install using a MPPT controller? How much "juice" would that provide my 8-12volt house batteries? Would it be a big help?

First things first, do you know how much power you want/need?

If you don't have one get a shunt based battery monitor. Amazon has them for about $45. This is an invaluable tool for boondocking/dry camping. This gizmo will count and show total amp hours available so you can figure out exactly how much battery capacity you have remaining. It will also show charging and discharging rates. By simply looking at the gauge you will know exactly how much power you have used in a certain time period and use that figure to size your solar system.

In our case we use about 30-40 AHs/day, more in heat or cold for fans or furnace. Two 120 watt portables fed through a Victron Smartsolar 100/30 MPPT controller does us just fine. The suitcase portable panels are re-wired to have each pair of panels be in series to up the voltage, reduce wire size, and perform better under marginal sun conditions, i.e. hazy/cloudy days.

We do have an absorption fridge, BTW.

We like the portables as they are a bit more efficient and you don't have to park in the sun to use them, a huge factor right now in the Pacific NW. Currently camped at relatively cool Tollgate, OR. but it still got up to 90 yesterday, much better than the 115+/- at nearby Pendleton.

As an aside, do watch out for voltage drop on the cable run, there are calculators out there. Less drop is better, obviously. Do try to keep it at 5% or less. Here is a calculator that I've used:
https://www.calculator.net/voltage-drop-calculator.html

[sailorman1]

Originally Posted by Desiday

I have a 2015 Newmar Dutch Star that is prewired for solar. It was prewired with 10 gauge wire. How many 100W panels can I comfortably install using a MPPT controller? How much "juice" would that provide my 8-12volt house batteries? Would it be a big help?

Assuming you use a MPPT controller and your panels have a voltage of 30v at max power power point, and the 1 way distance from the panel to the controller is 15'; you could install 7 100W panels in parallel that would be 23amps and if it all with through a 10awg wire would be 2.7% voltage drop. I wouldn't size for anything more than 3%

MPPT controller would drop that 30V to 12V and assuming an minimum voltage of 12.5V at the MPPT would produce 56ampss and if 10' from the controller to the batteries would need 4awg from controller to batteries.

In end the amount of solar you can install is going to be where in the system that 10awg wire is and how long the run is.

I have 640W solar, 10awg for about 8', then 8awg for 15' to controller, and 6awg for 5' from controller to batteries. I have never seen 640W produced and think most I have ever seen is low 400s. In summer conditions I can except around 200-220 Ah of "juice".