How Many Solar Panels Do I Need For My RV?
In total, for a standard Class C RV I would install 500 watts of solar panels with a lithium phosphate battery bank of 360Ah. This is the kind of power you need if serious about boondocking in your RV and you can upgrade from there.
I was prompted to write this post after coming across an article describing the new Dethleff Electric RV.
A solar electric RV seems to be the answer to a boon-docker’s prayer, and it’s advertised as an autonomous option, but it’s far from that.
Class C RV with solar panels
I’m a firm believer in reverse engineering existing good solutions to any technical problem and naturally took this approach when looking at the very common question of how to work out how many solar panels are needed for the average RV.
Incidentally, the Dethleff electric RV is not a good candidate for this approach.
Video – How many solar panels do you need on your RV?
In a previous post I looked at charging EVs with solar in some detail.
It is viable with around 2000 watts of solar panels, say 7 x 250 watts, to charge an average EV such as a Nissan leaf, but this assumes an average American commute of 30 miles a day, not the full range or capacity of the battery.
The Dethleff Electric RV boasts a 150 miles range without fitting out with its camper trim, so it will be less than this.
Also, the 3000 kW of solar panels is not going to provide nearly as much power as you might think. Look at the panel orientation:
- Top – in flat orientation solar panels lose 10 to 15% power output
- One side could be considered on average to be facing the sun at 90 degrees angle. This is not an efficient angle and power output will be down between 25% to 30%
- The opposite side can be considered to be facing North (the very worst orientation) and so output from this array will be down at least 30%
In short, covering an RV with solar panels is a bad idea and little more than a sales gimmick.
It is much more efficient to mount an optimum amount on the top of an RV where there is always a reasonable amount of sunshine.
How Many Solar Panels Do I Need To Power My RV?
More and more people are considering bugging-out and living off-grid in these difficult times when the future is pretty uncertain.
Some of the bigger RVs are ideal for couple or small families and autonomy becomes key.
We need to be less dependent on outside sources of almost everything, including electricity.
Solar PV systems and RVs go together hand in glove and it’s natural to wonder about the generation capacity of standard solar panels.
The standard approach is to gather all the energy requirements that you have or intend to have and work out the solar panel sizes you need.
I’m going to begin at the other end, by reverse-engineering existing systems available in the marketplace.
Are solar panels for an RV worth it?
Solar kits for RV are available on platforms like Amazon range from 20 watts to 300, so it isn’t surprising an RV owner can get confused.
Exactly how much solar do you need to power an RV? The key word is ‘exactly’. You really don’t need exact figures.
They are difficult to get anyway and all solar installers I know work on estimates for sizing and pricing.
How many amp hours do I need for my RV?
The average RV uses about 600kWh per month, so why not use this figure instead of doing all that complicated calculating? I do it anyway because this is a DIY solar blog but it isn’t really necessary.
(It isn’t a good idea to be using AC with solar in your RV while boondocking – it will really deplete those batteries!)
Let’s use this figure of 600kWh/month and the average Ah battery capacity is 180 (2 x 90Ah) at 12 volt which converts to 2160 watt/hours (W/h).
If you work on this basis you can always adjust up if needed.
How many amp hours is Boondocking?
2 days is a good amount of time to be free of all constraints so you will need enough solar panel capacity to keep those batteries topped up.
We need to assume some level of irradiance, which of course depends on your State.
Solar designers use the STC solar panel rating (its output in watts at an irradiance of 1000 watts/m2) multiplied by 4 hours of sunshine.
- A 100 watt solar panel will generate about 4oo watt/hrs per day = 12 kW/month
To completely cover all your needs you would need 50 x 100 watt panels! Clearly not an option, but of course the real situation isn’t like this.
The RV engine charges up the batteries while running (always an option) and naturally you cut down on energy usage.
How many hours would you like to be autonomous i.e. be boondocking?
If not running AC this figure comes down to 10 kW/day. Let’s look at the system again:
- Energy usage 10kWh/day
- 180 Ah Battery supplies 2.160 kW/h (if lithium phosphate used at 100% Depth of Discharge(DOD)
- 100 watt panels supplies 0.4 kW/h
How many solar panels does my RV need?
For minimum requirements I would:
- Increase battery Ah capacity to 360Ah (4320kWh)
- Install 500 watts solar for 2kWh/day
and adjust energy usage accordingly until you approximate 2 days boondocking.
The very best method for assessing your energy needs is to go RVing for a day or two and measure your energy consumption while you’re out. It easily done with a simply-connected DC energy meter.
I don’t advise using any kind of battery capacity monitor based on voltage. These are only useful if the batteries have been standing for several hours and are relatively stable.
MPPT Controller For RV Solar Panels
Whatever size solar array you decide on for you RV, you absolutely must control the battery charging with an MPPT controller.
The are two main type of controller, PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking.)
Without going into the technical details, the MPPT type is up to 30% more efficient, meaning you’ll get 30% more power out of your solar array.
Best RV battery for boondocking
For many years AGM or other types of deep-cycle batteries have been the main-stay of serious RV life but this is changing rapidly.
Lithium phosphate technology is changing the way we think about batteries. They are lighter and last much longer. The only drawback at the present time is the price, which can be more than twice as much.
Number charge/discharge cycles
2000 (100% DOD)
500 (80% DOD)
60% less than Pb
Inherently deep cycle
New RVs Class C size come with a 120Ah lithium phosphate battery, which is a good basis to begin with.
A good example of the kind of package you’re looking for is the Scandinavian Affinity Camper Van with 360 watts solar panels and a 120Ah battery – you can always add some!
Are flexible solar panels any good for RF roof mounting?
I’ve often seen it recommended but I wouldn’t do it myself. After all, they are made for fixing on uneven surfaces while RV tops generally have large enough flat areas to mount rigid solar panels.
Rigid is always strongest, although 4 to 5 times heavier, which isn’t really an issue with a camper van.
Buy individual components, rather than a kit. Kits just come more expensive IMO. Panels are cheap nowadays and a good MPPT controller isn’t going to break the bank.
The biggest expense is going to be the LiFePO4 batteries, and they are for life. Go RVing!
Renogy Solar RV Resources
Deep-Cycle Solar Storage Batteries
Can a wind turbine run an RV?
For sure, wind turbines can be a great option for RV life and boondocking. There a few things to keep in mind:
- Constant wind is best – think plains or coastal areas
- When wind speed doubles power output multiplies by 8
- Wind power is strong! Ensure fastenings are to manufacturer’s specifications
- Between 250 and 400 watts is a good size to begin with
- Don’t run a wind turbine while driving
- Wind power plus solar is the perfect combination – when one is low, the other is high
- About half the cost of solar panels
- Can be noisy – may need to be disabled in high winds
- Protect against lightning
Solar Direct Wind Power Products
Web Story – Can A Wind Turbine Power An RV?
Are solar panels for an RV worth it?
Solar panels have come down in cost considerably in the last few year and they are considered a great addition to an RV. 2oo to 300 watts of solar panels with 180Ah of lithium phosphate will go a long way towards extending your autonomy.
How much does it cost to install solar panels on an RV?
A kit consisting of 200 watts of solar panels and a basic PWM solar charge controller, including all the wiring shouldn’t cost more than $300, assuming DIY mounting and cabling.
What type of solar panel is best for RV?
The standard rigid monocrystalline type is suitable for all RV installations. Flexible models are not easily fixed and don’t last as long.