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Sizing Your RV Solar Power System

Sizing Your RV Solar Power System

How much RV solar do I need?

One of the top questions we get from readers is how much solar they need on their RV. We call this question because when users spend time in an RV, they begin to see the potential and rewards of being off the grid. A little further away from your neighbor, a little less in the city, and a little more peace and tranquility. Camping more remotely means removing the power cord and ultimately going off the grid. Your RV will be carrying your water and food and creating your power. Generating and storing your energy will keep your modern gadgets and technology alive in the wilderness. This article will discuss the factors that weigh on the size of your RV solar power system and what that means for each portion that builds the off-grid solar power.

Updated 01/07/2023

Sizing your RV solar power system

Sizing the RV power system is an essential part of succeeding in your long-term goal of having off-grid power or providing a certain amount of run time for remote devices in your Recreational Vehicle. To properly size the system, we must first understand the components we will need to measure so we can discuss the portions individually:

  • RV Solar Panels - these solar panels are either rigid or flexible and take sunlight and turn it into usable power. They can be portable, but most larger systems install on the RV’s roof.
  • Solar Charge Controller - this is the part of the system that protects your batteries from overcharging and can also, in some models, allow your system to use more available light.
  • RV House Battery Bank - these batteries provide power to all the 12-volt loads in your RV. Usually, this bank is where the solar array stores the power it generates. Today, these banks typically contain either AGM or Lithium batteries.
  • Accessories and safety gear - this is an essential part of the RV solar system as it makes clean installs and provides safety items like fusing, disconnects, and breakers.

The budget always controls the size of the RV solar array

Your budget is the most significant limiting factor for some RVers on how much solar they choose for your RV because you may want to limit your financial output. A good RV solar panel system with batteries will cost between $500 to $15000 before installation. When you set off to size your RV solar system, set a realistic budget for your total spend on the system. The areas that have cost components are:

  • Solar panel
  • Batteries
  • Inverters
  • Wiring and Installation kits
  • Fuses, Breakers, and Buss Bars
  • Chargers
  • Installation Services
  • Installation Accessories (Sealant, Bolts, Screws)
  • Shipping
  • Sales Tax

The solar panels

Anytime you want to figure out the maximum number of solar panels that can permanently install on your RV, it is critical to understand how much usable roof space you have on your RV. Each solar panel will take up a certain amount of area on the roof. There are already other items on the roof that will affect your solar panel configuration. Everyday rooftop items that impact RV panel placement are:

  • vent pipes
  • fans
  • skylights
  • air conditioners
  • luggage racks
  • antennas

To help lay out the panels on your roof, check out our RV solar panel layout guide.

Once you have the usable space calculated on your RV roof, you can determine the maximum square footage available for panels. Every solar panel on the market will have different dimensions and efficiency ratings. Some solar panels will produce more power per square inch than others. Panels also get more efficient over time. Solar panels made just a few years ago in a 140-watt configuration today are built to produce 200 watts in the same footprint. An extra 60 watts per panel on the RV roof from more efficient PV cells. If you have room for ten solar panels on the roof, with more efficient panel choices, your RV solar array is going from a 1400-watt to a 2000-watt solar array. That is a huge difference, so shop panels based on price and efficiency.

Solar panels are rigid rectangles of PV power that do not bend or fold around roof penetrations like air conditioners or vent pipes. So keep the obstructions in mind when laying out your solar panels. A reader once told me they call them “Solar Panels,” not “Shade Panels,” sho don’t block the sun because they don’t produce the same power when shaded. Funny but very accurate because shade certainly will impact power production.

Want to connect to the cable entry plate on the roof of your RV?

This cable entry plate is the best way to make permanent solar panel connections that are out of the way and mostly safe from theft. The CEP-25 has MC-4 connector attachments that allow for quick connecting solar wires to the panels. MC-4 cables will extend usually 18 inches from the panel. These should be fine to conenct to cable entry for a single panel install that is close to the cable entry plate. If you want more than one solar panel or you cable entry plate is far from panel install, ordering a couple of extra MC4 extension cables can make wiring easier on the roof. These cables are almost always ordered in pairs, so get two of them.

When adding panels this is where MC-4 branch connectors will come into play when wiring in a standard parallel configuration. Most of the expansion kits will come witht these although you can order them as matched pairs.

Panels and kits if you have a charge controller installed

A 30 amp controller can typically handle up top three of these 190 watt panels.

Go Power 190 Watt RV Solar Expansion Kit
MC4 Extension Cables

Full RV solar kit if you still need the solar controller

You can add up to of the expansion kits above to a the base solar kit below.

Go Power 190 Watt Overlander RV Solar Kit
Go Power 30 Amp Controller

More power-hungry devices and loads require more extensive solar power systems in RVs. Get as much solar as your budget and roof can support. One way to overcome the roof space limitation is to add portable solar panels to your solar array in your RV. Even these portable panels take up room and stow when not in use so these panels will have a cost and a limit.

Connecting to the solar port on the side of your RV

The port on the side is connected directly to the battery in most wiring setups. Check your Rv's manual to make sure this is the case.
This port has a standard connector in many portable solar kits. Commonly referred to as an SAE connector. Portable kits usually have the charge controller in line or on the back of the panel. This is why the port usually is wired directly to the battery.
If there is a side connection, a customer needs to look at our portable solar units and our portable solar guide for more information.

Many of the portable solar kits come with a wide range of connectors. This allows easy connecting to your RV and also other equipment.

Go Power 200 Watt Solar Kit
Go Power 130 Watt Portable Solar Kit
Renogy 200 watt portable solar kit
Go Power 90 Watt Portable Solar Kit

The charge controller

The charge controller is an expensive piece of the solar power system in an RV. It impacts the size of a solar array because there is an amperage limit on how many amps of solar it can handle. Some controllers allow linking, so more than one controller can take the production from larger arrays on motorhomes and fifth wheels and distribute it to house batteries.

Time to add more panels or look for a more power controller capable of hanadling series and series parallel wiring? Go Power's MPPT controller might be the one for you. [Go Power MPPT 60]( This controller has been the workhorse of many RV solar arrays. For larger arrays it offers great power and fleability. With tons of input and output voltages and even bluetooth connectivity. Take a hard look at this particular controller for your RV.

Shop the controller within your budget. PWM controllers are more budget-friendly and OK for smaller arrays, but the more expensive MPPT controllers are required for larger, more complex solar arrays.

The RV battery bank

RV battery banks are often left out of the planning for a solar system, but they are one of the most expensive and essential parts of the equation. Adding the batteries early in planning will allow you to consider their cost, capacity, and weight in calculating how much RV solar is needed.

There are a few choices for battery types in a solar array, but the most commonly used today are AGM and Lithium batteries. Lithium batteries are the standard for new banks as they last longer and have many power storage benefits.

Large RV 250 Ah lithium battery that is designed to operate at 12 volts

Go Power 250 Ah Lithium Battery

Go Power quality in a large amp hour 250 lithium battery

Lithium batteries are expensive and will be a considerable part of your solar system’s size and budget. Read Are RV lithium batteries worth the cost article to understand the cost versus features of lithium.

Saftey gear and wiring

Always remember the safety of your RV solar system when calculating cost and size. Never skip safety gear, and always use proper wiring for solar arrays. Larger arrays often operate at higher voltages which can be dangerous and may require professional support.

It is always best to hire a professional to install an RV solar system. You need to become more familiar with electrical systems’ risks and dangers as you set off to explore the world. The cost of a professional is worth your safety. Ask the installer to explain RV solar system operation, system safety, and safe troubleshooting. A straightforward way to disconnect all portions of the system individually is essential. Where necessary, check with local building codes to see if a permit is required for your RV solar power system.

### What is the right sealant for your solar intall? ** Always read installation instructions before installing your solar panels on your RV** Several factors go into choosing the right sealant when installing solar panels on your RV roof. - What kind of RV roof do you have? - How are you installing the panel to the RV? Screwing it dropdown - What color do you want the sealant? - How much sealant do you need? More than you think. Some intalls also recoommend buytl tape for placing in the holes. We have found more narrow pieces of buytl tape easier to workj with, but your mileage may vary.

An example of a larger solar array kit with controller is:

The answer to your off-grid refrigerator might just be the Go Power AE-6 kit

Refrigerators in Class A, Class B and Fifth Wheels have gone to residential types. These residentials types will not runn off of your battery bank alone. You need an inverter, a large battery abnk and solar panels to operate seamlessly. A generator on board is always a good choice as well.

Go Power AE-6 Solar Kit

Designed for refrigerators and larger loads

More power from the sun for faster recharge times

Just add a battery bank of 500 to 1000 amp hours, and this kit will usually support your fridge off-grid. There will always be low light weeks where a short generator run or plugin will kepp you going. The AE-6 has the power to keep it charging and running. The six in the name is for 6 solar panels.

There are also simple power stations that can offer simple solar power systems for your RV

Ecoflow Delta Power Station

Additional reads

Check out these articles for more information from Outside Supply.
12 Volt LED Cabin Lights
12 Volt LED Cabin Lights

Want to add light to your cabin? 12-volt LED may be the trick A simple round cabin 12 volt light fixture. 12-volt lights in a cabin can be the easiest way to provide lights without needing inverters or other equipment. In an RV, the lights run on 12-volt house batteries. When you flip the light switch, battery power flows to the lights without the need to turn on an inverter.

Sizing RV Battery Bank
Sizing RV Battery Bank

SIZING RV BATTERY BANK Choosing a battery bank size for your RV is crucial in having enough power to go off-grid camping. The first thing to consider when you are sizing RV battery bank is to determine how much space and weight carrying capacity you have available. Most battery types are heavy and take up a decent amount of room. Extra weight in your RV may require the need to be balance loads in your trailer or motorhome.

MC3 MC4 Solar Expansion Panel
MC3 MC4 Solar Expansion Panel

Which do I have, MC3 or MC4 Solar Expansion Panel? Do I have the MC3 or MC4 connectors on my existing RV Solar kit? A lot of times it is really easy to determine, you just need to have access to the connectors on the existing system. Once you have the connectors visible, you should be able to see the side of the connector for the MC3 or MC4. An MC4 connector on the end of the solar power cable has locking tabs on the side.