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How Many Solar Panels are Needed to Power a DIY Camper Van Electrical System

Solar panels take the energy from the sun and send it down through a charge controller where it will eventually recharge the batteries in your Camper Electrical system.

Quick note before we get started.  This is just one part of a overarching “How to Install a DIY Camper Van Electrical System” series.  If you’ve just stumbled on this article directly without seeing that, there are likely some things we’ve already covered.  If you want to check out that step by step guide, you can do that here: https://www.explorist.life/diy-campervan-solar

Also, we have interactive solar wiring diagrams that are a complete, A to Z solution for teaching you exactly what parts go where, what size wires to use, fuse size recommendations, wire lug sizes, and all kind of other stuff to help save you time and frustration.  You can check that out here: https://www.explorist.life/solarwiringdiagrams/

“How many solar panels do I need to power a camper”?

First off… Stop thinking in ‘number of solar panels’. Solar panels are measured in watts. There are 100, 170, 200, 225, 265, 300, 335, and 360 watt solar panels.

I missed a few, but the point is, there are MANY different sizes of solar panels on the market and 3, 100 watt solar panels will have the same output as a single 300 watt solar panel.

So: The number of solar panels doesn’t matter.

What DOES matter is the total wattage of the entire solar panel array, which is the wattage of the individual solar panel multiplied by the number of solar panels you have.

3 x 100 watt solar panels equals a 300 watt solar array

How Many Watts of Solar Panels are Needed to Power a Camper?

Now that you are thinking in terms of the size of the solar panel array, it’s time to determine how many WATTS of solar panels you need.

You’ve already figured out how many amp hours of batteries you need from your solar power audit. We will be working off of that number. More specifically, we will be working off of the USABLE amp hours of your batteries.

You need your USABLE battery capacity to determine wattage of solar panels.

Your batteries should be sized for your electrical demands. Your solar panels should be sized to recharge your batteries.

*Don’t think about your solar panels running your electrical devices. Your BATTERIES run your devices. Your Solar Panels re-charge your batteries*

How Many Watts of Solar Panels do I need to Recharge my Batteries?

  • 100 Amp Hours of Useable Power from a battery contains roughly 1280 watts of power (100ah x 12.8 volts = 1280 watts of power)
  • The average hours of sunlight per day in the continental US is 6 hours.
  • battery holds about (100ah x 12.8 volts =) 1280 watts of power roughly.
  • To charge
  • 100 Amp Hours (useable) or 1280 watts of battery in 6 hours, you will need 213 watts of solar panels. (213 watts of solar X 6 hours = 1280 watts of stored power)

Key Takeaway: Estimate 200 watts of solar panels per 100 amp hours of useable battery capacity (100Ah Lithium or 200Ah AGM). BUT KNOW THIS: More solar panels are just going to charge your battery faster, or more adequately in low light conditions. If you have 400 watts of solar, you will charge twice as fast. Increasing the number of solar panels will also help compensate on cloudy days.

Key Takeaway #2: If you want more battery capacity than you have roof space for solar panels, that’s fine! You will ALSO be charging from your alternator and you will also have the option to charge as needed from shore power, or a plug-in at, say, a house, campground, or even a generator. This system is all about being versatile.

Spare me the labor and just give me the baby:

 I recommend 200 watts of solar panels per 100 useable amp hours of batteries as a base guideline.

Once you know the total wattage you need, you can divide the total wattage up into the individual solar panels you would like, which will likely be based on roof space available.

Common Battery & Solar Panel Combos

Now that you know how many and what kind of solar panels you need for your DIY Camper Van electrical system, it’s time to learn if you should wire your solar panels in series or parallel (and why we recommend series in 90% of scenarios). Check that out here:
https://www.explorist.life/solar-panels-series-vs-parallel/

Everything that you are learning here is put to use in our FREE Interactive Solar Wiring Diagrams.  If you haven’t yet, check them out as they are a complete solution for a camper van electrical system.  Check them out here: https://www.explorist.life/solarwiringdiagrams/

Remember, this is just one part of a full camper van electrical educational series.  To see all of the individual guides, click here: https://www.explorist.life/diy-campervan-solar


Keith Cuddeback

Thursday 10th of March 2022

Nate, you seem to be the most knowledgeable person I’ve run across around camper electrical systems. May I ask you for your opinion on current situation which is replacement of my batteries?

My Sprinter came equipped with 8 220Ah 6v. golf cart batteries wired into a 24v bank and a 5 kw inverter. This gives me 880AH of power with 440AH useable, if I’m understanding the system correctly. The solar panel is a small 240w unit which i know is too small to charge depleted batteries but does keep up with the batteries when storing the van.

I saw on one of your videos that you can swap out AGM for lithium and simply change charging parameters on the inverter and solar controller. An RV tech I discussed this with says I’d need to also swap out my UHG, inverter… everything. True?

So, my question is; can a swap be the easy way to go and would I need 2 or 4 lithiums in order to keep my current equipment in a 24v setup?

Thanks so much for all your great videos and any advice you can offer on my situation!

Cheers!

Keith

Ged

Wednesday 2nd of March 2022

Hi. Thank you for your very informative you tube channel. I want to create a 48v system in my camper running a 10kv iverter/charger. My method of thinking for the solar is 2 strings of 4 400watt panels connected in parallel. My maths tells me I would have about 3.2kw of solar, is this correct? Best regards Ged

Kevin

Thursday 9th of December 2021

What’s the best battery to get there is so many out there and they’re so high priced so I heard there’s a new battery out that and I don’t know if it’s being manufactured yet or not but so what’s the best battery to get and how many

Nate Yarbrough

Thursday 9th of December 2021

I recommend Battle Born batteries. They are a great battery, but more importantly, they have phenomenal customer service that will be there for you when something goes wrong. Check the wiring diagrams at https://www.explorist.life/solarwiringdiagrams to see how these look in a full system.

For 'how many', you need to do a power audit. Here is a tutorial for that: https://www.explorist.life/what-size-of-solar-system-is-needed-to-power-a-camper/

Daniel

Thursday 14th of October 2021

What size panel do I need to run my 3 120amp batteries that will be all connected as 1

Jim

Sunday 29th of August 2021

I was hoping to use flexible solar panels on my pop-top. What is your experience with them and do you recommend any that are equivalent to rigid solar panels for quality and reliability?