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if you look up “how much solar power do I need for my camper”, you will probably find something like “x number of solar panels”. But the number of solar panels is not nearly as important as the size of the solar panel, and this is measured in watts.
A typical camper needs a 200 watt solar panel for every 100 usable amp hours (ah). The more watts your solar panel has, the quicker the charge. Having additional solar panels also speeds up charging when it’s cloudy. The more appliances you decide to run, the more power required.
How Many Watts Do I Need?
The most common portable solar panels are 100 watts, but 50, 80, 150, 200, 300, 350, 400 watts etc are available. You can also add more panels to an existing solar panel to form an array, so a single 400 watt solar panel produces the same as four 100 watt solar arrays.
First you have to find out how many battery amp hours you use. Take your camper out for a drive and check how much ah you use in a day. Use this method to find out what battery size you will need. keep the following in mind:
- Lithium batteries have full nominal capacity. if it’s 100 ah, 100 ah may be used. If it’s 200 ah, 200 ah can be used and so on. However, many suggest recharging before the energy level drops to zero.
- Lead acid and AGM have a 50% nominal capacity. That mean a 100 ah lead acid battery must not go below 50%, a 200 ah battery is usable down to 100 ah, 300 ah it is 150 ah and so on.
- Your batteries should correspond to your power needs. Power hungry appliances like a refrigerator requires a lot of batteries.
- Your solar panel wattage must correspond with your battery’s usable ah to recharge it. Remember, the solar panels draw energy from the sun. This is stored in the battery and you use the battery to power your camper. Wen the battery runs low on power, you use the solar panel to recharge them.
Popular Solar Panel and Battery Combinations for Campers
Here are some of the combinations that campers use. These are popular, but you should mix and match them to suit your requirements.
- 1 x 100 watt solar panel 100ah AGM battery
- 2 x 100 watt solar panels 200ah AGM battery
- 2 x 175 watt solar panels 200ah AGM battery
- 2 x 175 watt solar panels 100ah lithium battery
- 1 x 300 watt solar panels 100ah lithium battery
- 3 x 175 watt solar panels 200ah lithium battery
- 2 x 300 watt solar panels 200ah lithium battery
For more power and capacity, you can try the following combinations. While these examples use lithium ion, you can opt for their lead acid equivalent.
- 4 x 175 watt solar panels 300ah lithium battery
- 2 x 300 watt solar panels 300ah lithium battery
- 5 x 175 watt solar panels 400ah lithium battery
- 3 x 300 watt solar panels 400ah lithium battery
- 6 x 175 watt solar panels 500ah lithium battery
- 4 x 300 watt solar panels 500ah lithium battery
- 7 x 175 watt solar panels 600ah lithium battery
- 4 x 300 watt solar panels 600ah lithium battery
What Appliances Can Run on Solar Power Camper?
The table below tells you that for small appliances, portable soar panels will suffice. For power hungry appliances like a refrigerator, washing machine, microwave etc., you need a lot more power. The list also shows you can use these appliances for only a specific number of hours in a day. You can use the small ones together but not when running a fridge.
|Appliance||Watts||Usage Per Day||Daily Consumption (Wh)|
|Mini fridge||200||24 hours||4800|
|Light bulb||60||6 hours||360|
Many campers and RVs are advertised as “solar ready”, but not all are meant for heavy duty use. Solar ready means the RV or camper has been configured so installing a solar panel system is easy. They do not include solar panels. A typical solar ready camper has enough power to operate:
- Propane powered fridge (a few hours)
- Furnace (limited time)
- Vent fans
- LED lights
These devices can be run for short periods after sundown. Afterwards you need to recharge the batteries again. If you’re a weekend camper then this will suffice. But if you want to deck your camper with full blown appliances and live off the grid, you have to make batteries last longer or buy a higher capacity battery.
How to Run Large Appliances in Solar Power
A 12V battery is not enough to run large appliances in a camper, so get more power. Second you need an inverter to convert the power to 120 volt AC to run appliances. A portable inverter is suited for charging laptops and mobile devices, but for microwaves or an air conditioner you need a more powerful inverter. You will also need:
Solar panels: For power hungry appliances you should get 400 watt solar panels. You have two choices: monocrystalline and polycrystalline solar panels.
Monocrystalline solar panels are 10% to 15% more efficient in converting sun energy, but they are also more expensive than polycrystalline. However the difference in price can be minimal depending on where you buy. it really depends on how good the solar panel was designed, as well made poly panels can still do a good job.
Display Monitor: an indispensable tool. With a monitor you will know right away when your system requires a recharge or if it is full. There are apps available so finding one should not be a problem.
Inverter: a portable inverter is fine for that laptop, but to run that big screen TV you have to sacrifice portability. A 3000 watt inverter is just about right. These inverters can be quite large, but again you have to give up portability for power.
Solar Charge Controller: the solar charge controller serves as the voltage current regulator. It ensures your battery gets the maximum amount of power without overheating or overcharging. Bottom line: get the best battery charge controller you can afford.
The most widely used inverter types are MPPT (Maximum Power Point Tracking) and PWM (Pulse Width Modulation). MPPT is going to cost more but it converts extra volts in amperage. The higher the amperage, the quicker your batteries recharge. This feature is particularly important during cloudy days and more so during winter.
Batteries: suffice to say that for power hungry appliances, the bank capacity must be large. Calculate how many amp hours you need (discussed earlier) and use that as guide to find the right battery.
Three choices are available: lithium, AGM and lead acid. Lead acid is the most popular but because lithium has 100% nominal capacity, it has an advantage. Lithium batteries also weigh less. more amp hours plus portability are huge pluses.
Lithium batteries are more expensive, but they have a longer lifespan. There is no venting required so you can place it in your camper or RV. The advantage of lead acid batteries is they are cheaper and more widely available.
What You Can Run With a 400W Solar Power System
A 400W solar system is ideal for most campers. With this you can comfortably run a good number of appliances and devices. You could easily run the following for instance.
- Coffee grinder
- Coffee maker
- Hair dryer
- Game console
- Wi-fi router
- Apple mini server
- A couple of 40 in TVs
You cannot run a refrigerator or space heater without turning off the other devices. You can probably do it with power management, but the battery will run low quickly. As to how long the battery lasts, it depends on how much you use the appliances and how energy efficient you are.
How Many Solar Power Watts Do I Need to Recharge Batteries?
100 ah usually has 1280 watts and a standard battery has 1280 watts too. A typical day in the US has 6 hours of sunlight. To charge 1280 watts in those 6 hours you need six 213 watt solar panels. If you can get a 400 watt solar array you can cut the charge time to 4 hours or less.
Whether you get a single 200W / 400W solar array or connect several 100W cells is up to you, and usually it comes down to how much space is available. If you want to go off grid full time, get a good sized solar panel or set up an array.
It is cliché, but the answer to the question “how much power” is “it depends”. For basic camping, a couple of portable panels will do, but if you want a fully rigged camper, you have to amp up the power. As we have shown above there is quite a bit of planning to do, but that’s part of the fun of living of the grid.