San Diego California Campground Sunset

RV Solar Series: Inverters

RV Solar Series: Inverters change Direct Current (battery power) to Alternating Current (house power) so that you can use house appliances inside your RV.

Some RVs don’t have any inverters and some RVs have huge inverters. Some, (usually older) RVs don’t even have a battery (this is very rare). My RV has a small inverter, intended just to run the televisions.

Camper or Tour Bus

Our RV design was more of a camper than it is a tour bus. I used to be able to say that you can tell the difference by the refrigerator. (that indication has changed because RV manufacturers have blurred the lines)  If the refrigerator is AC electric only, then you have an RV intended to be in an RV park. If the RV refrigerator operates off of propane, then you have a camper.

This, however, isn’t true anymore because RV manufacturers are putting AC only, residential refrigerators in most RVs that would normally be considered a camper.  My RV is a camper that looks like a park model RV.  Why do I say that?  First, our RV has an expensive look but is on a school bus frame.  More expensive RVs are on city bus frames. We have a gasoline engine. More expensive RVs have diesel engines. We have the same brake system and suspension as an old truck. More expensive RVs have air brakes and air suspension.

The most expensive RVs you see driving down the road don’t usually camp like I do. Typically they will go from RV Park to RV Park, from electricity site to electricity site.  Their battery limitations and my battery limitations are similar. Overnight, not too often. I would say that in camping style I have more in common with trailers than I do with the most expensive RVs.

Go Bigger

The reason I go into this detail is that electric power needs are different for trailers and luxury motor coaches. You can put solar on a luxury motor coach but you are going to have to go bigger. I want to go bigger, to increase the enjoyment of my camping style.  My RV has a microwave. I paid for an RV with a microwave — and I want to use it. 

I have been pushing the camping envelope for quite some time. In 2017 we went several days in a row without solar power and only used the generator to recharge the battery.  Last year (2018) we spent multiple stops with several days without outside electricity and measured precisely how much electricity we used.  This year (2019) I just finished 10 days in a row with solar doing all the re-charging.  Each night the temperature dropped into the 30-degree range, it was just like winter camping. The heat came on just like you would expect.

Battery Limitations

The limitation electrically is battery power will only take us overnight (not a problem if the sun shines the next day) and a small inverter.

Almost as a side note, my inverter, and any inverter that I would consider is called a pure sine wave.  The opposite would be a far less expensive modified sine wave inverter. Without going into much detail,  pure sine wave inverters are the only way to go. Many devices such as my air conditioning fans, compressors, microwave, televisions, and computers are not going to be happy with a modified sine wave inverter and will either die early if they do work or refuse to work. 

Inverter graphic
RV Solar Series: Inverters graphic

The inverter is the device that changes battery power (DC) to alternating current (AC) and we like AC throughout the motor home to run typical appliances, like my computer or televisions. The few appliances that we have that would consume lots of battery energy are in the kitchen.  The microwave/convection oven is the number one energy hog that would kill my battery as it currently stands.


Killing my battery with the microwave is not a possibility because it is not hooked to my 750-watt inverter.  Good thing because the microwave has the ability to draw 1500 watts. The only devices hooked to the inverter are the televisions that I have already described.  I usually keep the inverter off because of overhead power draw – even if it isn’t actually powering anything.

To run the microwave I need a bigger battery bank and a bigger inverter that has the ability to power the entire coach.  There is little reason to have a massive battery bank and double the solar if all I do is carry the batteries for extra cloudy days.  The big inverter is on the list.

The layout of my RV AC power system:  The first step along the list of items associated with my AC electrical system besides the cord is an automatic transfer switch.  This device selects generator power when the generator is on and selects to shore power (RV park power) when the generator is off.  Both the generator and shore power are AC sources and big enough to run everything in the RV.  If the generator is off and the shore power is not plugged in, then the only source of AC power is the inverter which takes DC power from the battery and enables the entertainment system to run.

If I had a bigger inverter or added a second inverter to the system, I could operate the entire coach AC electrical system from the batteries; not just the entertainment circuits.

Multiple Inverters?

Having two inverters also have advantages.  My inverter and anyone that I would buy has a built-in battery charger that takes AC power from the generator or shore power and re-charges my battery.  If I had two inverters I could then recharge lithium batteries at a much faster rate than a single inverter could supply.  This is not a good idea with my AGM battery but would be a great idea with lithium batteries.

Additionally, almost as a side note, my engine alternator also recharges my batteries but at a very slow rate. When I drive, my solar will also charge my battery at the same time.

Besides the question of do I change my inverter, or add a second inverter is coupled with the question of do I stay with 12-volt battery storage or convert to 24-volt battery storage? 

RV Solar Series: Inverters change the way you live and what you can do in your RV. It isn’t a simple question of just an inverter size of both the inverter and the battery both create a balanced answer.

Update: April 10, 2020, Our old RV had a 750-watt inverter. Our new RV has a 2800 watt inverter. Our new inverter powers our refrigerator and can run one of my air conditioners.

Update: September 15, 2020, Our new inverter and our lithium can run both our refrigerator and one of our air conditioners — both at the same time powered only by our battery. Here is the story. Air Conditioning on Batteries and Solar

We created this site to help our friends with their RV questions. Feel free to ask questions or comment and we will address them to our best abilities.


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