RV Solar Installation: How we power our home with sunshine
February 24, 2021
Original post written by Kevin and posted in May 2020
Post modified by Kara and published February 2021
Our motorhome, Pippi, is powered by the sun. In 2019-2020, we completed our RV solar installation including roof-mounted solar panels and new lithium batteries.
One of the fascinating things about living in our RV is its self-sufficiency. Our solar panels convert sunlight to electricity and the energy is stored in lithium batteries allowing us the freedom to live off the grid in our RV with more flexibility.
What does self-contained RV mean?
Our rig is completely self-contained. That is to say, we have full functionality without the need for external services such as water, sewer, and electricity.
We have an 85-gallon fresh water holding tank to supply onboard water. Our sink and shower water drains into a grey wastewater storage tank. Our toilet flushes into a black wastewater storage tank.
We eventually need to dump our wastewater somewhere appropriate and refill fresh water. There is no real way around those limits however we can live conservatively for more than two weeks before needing to dump wastewater or refill fresh water.
How does an RV get electricity?
We already have an abundant power source with our onboard generator. It runs off the same fuel tank that powers the diesel engine pushing our home around the country.
Our fuel tank capacity is 125 gallons. As you might imagine a fill-up at the pump can be painful to the wallet.
The generator can run for two to three hours on a gallon of diesel depending upon the power needed. So, we can use the generator for a very long time before needing to refill diesel.
RV Generators Aren’t Perfect
However, diesel fuel is a non-renewable resource and we try to live an eco-friendly life.
The generator hum, while relatively quiet, is not ideal in picturesque natural destinations. Also, the smelly exhaust can force us to keep our windows closed when we would otherwise be enjoying the fresh breeze.
We decided to make some electrical upgrades to limit our reliance on the generator while camping off-grid.
How does an RV store power?
Power storage is typically the limiting factor in many stock RVs.
Most RVs have propane on board, and some have a fuel-powered generator because both are energy-dense storage options.
There is also a primary need for12-volt electricity for a lot of functions in an RV, such as lighting and various electronic controls. Therefore, batteries are standard equipment in every RV.
Standard RV batteries are similar to the batteries in an automobile but sturdier to handle the constant draw. These wet or flooded lead acid batteries are the limiting factor of power storage mentioned earlier.
What is a Flooded Lead Acid Battery?
Battery technology has been around for hundreds of years. Standard batteries, also known as, flooded lead-acid, were invented in 1836.
Flooded batteries have a lot of downsides and the main ones are:
Long charging times due to internal resistance
Voltage sag can limit the capabilities of large loads
Require annoying mandatory maintenance
Limited life expectancy (4-5 years)
Must be fully recharged with every cycle
Can only use half of the stored energy to maximize the useful life
In other words, they are not ideal and haven’t changed much over the years. That is until relatively recently. Electric cars have become more common and that is a direct result of advancements in battery technology.
Benefits of Lithium Battery
We chose to incorporate these advancements into our motorhome energy storage solution with Lithium Iron Phosphate (LiFePO4) batteries.
The benefits of lithium versus standard batteries are:
Fast charging due to very low internal resistance
Half the weight of standard batteries
Insignificant voltage sag even with high loads
Twice the life expectancy of standard batteries (10+ years)
Doesn’t care if it is fully charged during the cycle
Can use almost all of the stored energy without risking lifespan
Lithium batteries maintain an almost constant voltage no matter if they are fully charged or near-empty which is better for the items using the electricity. The density of power storage is higher in lithium which means more storage capacity in the same space.
The negatives of lithium are primarily the high upfront costs and limited cold weather functionality. Lithium batteries do not like temperatures below freezing but neither do I.
Why upgrade to lithium batteries?
With our lithium battery upgrade, we got 140% more usable stored energy in essentially the same space at half the weight of the old batteries.
The project was extensive as we needed to rebuild our battery bay after years of acid deterioration from the typical venting of the old batteries. Thankfully, lithium won’t do that.
We also had to make some electrical modifications to the coach so the batteries would play well with the various systems. We did some re-configuring of the battery tray and tie-down system to accommodate the different layout of the batteries. I also built new battery cables.
RV Solar System
We also incorporated a solar array into our new RV power system. We added 800 watts of solar panels on the roof as Phase I of the design. Phase II is another 800 watts but that phase has been postponed as a result of COVID-19 and the subsequent delays of production coming out of China. Update: We were able to finish the Phase II of the installation in December 2020, once panels were available.
RV Solar Installation
This project involved more time researching and planning than the actual installation. Once it was designed and parts ordered, the install was a matter of securing panels to the roof, phishing some cables, and making various wire connections.
Can I add solar panels to my RV?
If you have roof space and a bit of a DIY spirit, you can add solar panels to your roof.
Again, planning is key to a successful installation. Measure your roof including any obstructions to create your panel layout. Avoid installing panels in areas that are shaded by roof air conditioners, vents, or satellite dishes. Direct sun is the key to optimal solar production.
How do I convert my RV to solar power?
The actual RV solar installation was not very difficult if you have basic electrical experience. However, the research and proper design were crucial. I designed my system based on guidance and assistance from others including several online tutorials and solar forums.
How many solar panels do I need to run an RV?
When it comes to RV solar installations, one size does not fit all. Our design includes 1640 watts of solar (eight panels) and a 540 amp-hour lithium battery bank. However, there is no single ideal RV solar solution.
How many watts of solar do I need?
Solar capacity will correlate with a properly sized battery bank. Once you know the battery bank size you can plan a solar array that is 2x-3x the battery bank. For example, a 500 amp hour battery bank would be happy with a 1000-1500 watt solar array.
How much RV battery capacity do I need?
Battery bank size will vary based on your power usage and how frequently you want to run your generator. If you want to minimize the generator usage a battery bank typically should be the equivalent of a couple days power usage. This will help in the event of cloudy days. Some people can survive with a smaller system especially if their kitchen is powered by propane and they don’t use a lot of electricity.
We spent several weeks measuring and calculating our power consumption to properly size our system. We used a Killawatt (TM) meter on individual A/C powered items, such as kitchen appliances. It measures actual usage when you plug into it. If you have large D/C power demands, a battery shunt can be used to measure these loads and will be helpful in monitoring your batteries as part of your new system capabilities.
We used the collected data to determine our true needs. Based on our study the main power users in our motorhome were: our residential refrigerator, electric induction cooktops, and microwave/convection oven.
How much does it cost to put solar on an RV?
Again each RV solar installation will widely vary in price. We’ve seen campers with small RV solar systems consisting of a single $200 ground deployed solar panel. At the other end of the spectrum are those who pay $20k-$30K for professional RV solar installation including all new electrical controllers, inverters and lithium batteries, with the higher end reserved for capabilities of running air conditioners without a generator.
Our solar panels were about $200 each but wiring and accessories added to the overall costs. I would recommend building your system in phases as you can afford it. The key to a phased approach is building to easily allow for future expansions.
Should I add solar to my RV?
If you spend the majority of time with electric connections in campgrounds, then RV solar is probably not a wise investment, except maybe a small setup as a battery maintainer while in storage.
We like camping on public lands without shore power available so solar made more sense for us. But honestly, I enjoy watching the output of the solar array knowing it is feeding into those batteries for our future use. It is great to know we are able to live comfortably off-grid.
Our RV solar system has also come in handy in less remote places. For example, we spent four days at the Albuquerque Balloon Fiesta where we had no electrical hookups. We only ran the generator once although the rigs around us ran theirs for hours on end each day.
Do I need an RV generator?
Thanks to our RV solar installation, we are now able to park in remote places and not need to run our generator very often.
During the summer months, our solar produces excess power, sometimes even enough to charge our plug-in electric hybrid car. During the long days of summer, we only run our generator to exercise the engine as recommended by the manufacturer . However, during shorter winter days or multiple cloudy or rainy days, we supplement solar energy production with our generator.
Having redundant systems while living off-grid is important to ensure functionality is not lost when a primary system fails. We enjoy having the option of running our generator if needed or if caught in an unexpected heat wave for our air conditioners.
Is RV solar worth the money?
None of the improvements we made to our RV electrical system including solar panels and lithium batteries were necessary.
It can be debated whether the improvements are economical since we can cheaply run our diesel generator. It can also be debated whether solar is environmentally sound, but most agree in the long run it is better than the alternative.
Our electrical upgrades were significant and pricey. However, the modifications and resulting increased capabilities have greatly improved our quality of life.
Our RV solar installation also provides the freedom to be self-sufficient. We look forward to parking in some remote places with beautiful backdrops and not giving up our amenities or having to listen to our generator.