An electric water heater in a skoolie is the most ideal situation when the goal is to reduce the number of fuel sources on a skoolie down to two, electric and the fuel used for powering the engine.
We believe future skoolies will be down to one power source when electric school buses start hitting the aftermarket and get converted to skoolies.
Electric is going to be needed for your fridge, air conditioner, lights, electronics, and other appliances. Even though electric hot water heaters do pull a good amount of amps, they do not run for too long when they turn on.
We wanted to see if going electric was the best skoolie water heater option and figure out what was the true power consumption of the most popular electric water heater on the market.
We performed a test on the popular Bosch electric water heater that we detail out in this guide so you know exactly how much power these units may consume. Then, we dive into is the skoolie electrical scenarios where an electric skoolie hot water heater works best.
Skoolie Electric Hot Water Heater Power Requirements
The Bosch hot water heater is the most popular hot water heater installed into skoolies. This skoolie hot water heater consumes 12 amps per hour at 120V AC, or 66.24 amps per hour at 24V DC, or 132 amps per hour at 12V DC. This is the power ratings and not how much power the water heater will actually consume per day.
We have a Bosch 4 gallon electric hot water heater that we installed in 2021 after using a liquid propane hot water heater for the first 2 years of living full-time in our skoolie. This change was made after investing an additional $7,000 into our skoolie solar power system a few months prior.
This 4 gallon is the mid-sized unit of the Bosch electric hot water heaters that are the most common electric hot water heaters used in skoolies, RVs, and van conversions.
All of the Bosch hot water heaters come with the same power consumption parameters. Here again is the amp ratings of the Bosch electric units:
| 12 amps per hour @ 120v | 132 amps per hour @ 12V DC | 66.24 amps per hour @ 24V DC |
This looks like a good amount of power will be consumed, but the hot water heater will not be consistently running and once it is up to temperature the first time it will consume less energy to maintain the temperature.
There are a few things that affect how long and how often the hot water will run to maintain the temperature:
- How often hot water is used: As hot water is being consumed the unit will replenish with fresh water from your fresh water tank and need to heat back up to temperature.
- How cold the incoming water temperature is: Colder incoming fresh water will take alot longer to heat up that warm fresh water.
- What the temperature of the hot water heater is set to: If you have the temperature set very high, it will take the unit longer to heat the fresh water coming into the unit to the desired temperature than it would if the unit was set to a low setting.
The Test: Skoolie Electric Hot Water Heater Power Consumption
We know how much power the unit is rated to consume, but it doesn’t really tell us how much power is consumed by an electric skoolie hot water heater. So, I put a meter on my unit to test it.
I want to make a note that your water consumption may be different than ours as we did not shower in our skoolie during this test, bathe our dog Cali, or do any other higher random water consumption events.
The results from this test should be used as a general guideline for calculating the power consumption of a skoolie electric water heater.
Testing Duration
I put a power consumption meter on the plug for the hot water heater for 3 days, checking it every 24 hours to see how much power was consumed throughout the day. We used water regularly when washing hands, doing dishes after we ate, etc.
Unit Tested
As previously mentioned, we have the 4-gallon Bosch electric hot water heater. They also have a 2.5 gallon and 7 gallon that may run more or less than our unit to maintain temperature due to the amount of water it holds and how often the water temperature drops to kick on the heating element.
Temperatures During Test
It was the middle of winter in Wisconsin when we did our test. This is our highest power consumption period for a hot water heater. The water in our fresh water holding tank is cold. We are almost always using a bit of hot water mixed with the cold holding tank water to wash our hands, otherwise, our hands would freeze. The skoolie is being heated by our diesel heater, but the ambient temperature around the water heater is colder than it is in Spring, Summer, or Fall.
- Outside Temps: 14 – 23° F during the day and 4 – 11° F at night
- Fresh Water in Holding Tank: 40° F
- Inside Temp by Water Heater: 70° F
How Much Power Does a Skoolie Electric Hot Water Actually Consume?
An electric water heater in a skoolie is one of the most power-consuming appliances, third to an air conditioner and a fridge. The popular Bosch electric consumed an average of around 1.01 KWh per day when the ambient temperature around it was 70° F. This is roughly 25.5 Ah on a 120V per day, which converts to 281 Ah on 12V or 140 Ah on 24V battery bank systems.
Electric Hot Water Heater on Solar Power
It is definitely possible to use an electric hot water heater on solar power in a skoolie. The two ways to accomplish this are with a large solar power system including an adequate battery bank, or a smaller solar power system with an added DC-to-DC charger to charge the battery bank when driving.
However, having a large power system with a DC-to-DC charger is the best electrical setup for powering an electric water heater in a skoolie.
Large Solar Power System
If you are one of the many planning to spend a good amount of time in your skoolie traveling, I would personally go with an electric hot water heater if you plan on having an oversized solar-powered electric system and do not want/plan to have propane for any other purpose.
Small Solar Power System + DC-to-DC Charger
You could get away with an electric hot water heater by having a smaller solar power system with a DC-to-DC charger to charge the house batteries when you drive. I would only go this route if you plan to be driving on a regular basis.
Large Solar Power System + DC-to-DC Charger
Having a large, oversized solar power system with a backup DC-to-DC charge to supplement the solar system when the sun is not present for a few days would be the best option.
Sarah and I personally plan to have multiple options for every utility including having a large solar power system with an oversized battery bank with a DC-to-DC charger.
Final Thoughts
Adding on a hot water heater onto your skoolie’s electrical system might not really be a big deal as long as you have a properly sized inverter to withstand the power draw. Also, make sure to have a properly sized battery bank to store enough power for the water heater to run throughout the night as needed.
If you are nervous about running out of power, make sure to have a battery meter on the battery bank and a DC-to-DC charger hooked up between the main bus batteries and the interior electrical battery bank so you can use the skoolie’s engine to replenish power when the battery is low.
