Engel fridges and freezers have long been the go-to option for camping and road-tripping, providing an off-grid solution for keeping food(and beers!) cold without access to mains power.
Of course, they’ll need to be powered somehow, and unless you want to run your car battery flat within a day, the best course of action is a small solar panel and battery set up specifically for the purpose.
But exactly what size solar panels are needed to run Engel fridge freezers?
As a general rule of thumb, you’ll need a panel of around 100 watts at the very minimum for a 40-liter fridge, but a 200-watt panel is ideal.
This answer depends on a variety of factors; the size of your Engel fridge-freezer, how long you want it to run, and the temperature you’re running your fridge at.
In this article, we’ll be covering the following:
- Calculating your power requirements
- Factors affecting power consumption
- The ideal solar panel size
If you want to know the exact size of the solar panel setup you’ll need to run your Engel fridge freezer, you’ve come to the right place! Read on below for our in-depth guide.
Factors that Affect Power Consumption
Before we jump into the article, it’s important to understand that various factors affect the power consumption of your fridge and not just the power rating stated on your Engel.
Let’s take a look at some of these factors below.
How many amps per hour does a 40L Engel fridge draw?
According to the specifications on the Engel website, Engel’s fridge-freezers can run on 12 or 24 volts DC with a variable power draw from 0.7-2.7 amps (12V DC).
However, this “variable” power draw is somewhat misleading, as the fridge will draw a fixed current (2.7 amps) whenever it is running the compressor.
So, your fridge will draw 2.7 amps per hour with the compressor running continuously, or 0.7 amps when the compressor is not needed much.
Ideally, your fridge will be running somewhere in between these two extremes, with an average of 1 amp per hour without the freezer.
- Remember that no matter the settings your fridge is on, lowest or highest, its efficiency will still be subject to the ambient temperatures around the fridge.
So what this means is that your fridge will typically run far more efficiently in cooler temperatures than in warm temperatures.
Of course, your thermostat setting will also have a large part to play in the power draw and the size of your fridge-freezer.
Keeping your fridge in a cool, well-ventilated place will help reduce consumption as this will reduce the need for the compressor to kick in and keep it on the lower “fridge” setting as much as possible(perfectly cold enough for beers!).
Opening and closing your fridge constantly will also affect its consumption, and using the freezer setting will typically use around 25% more power.
How often should an Engel fridge cycle?
In light of everything discussed above, it should be clear that your Engel cycle rate will certainly affect its power consumption.
Under normal ambient conditions, your Engel compressor will typically cycle four or five times per day, depending on how often the door is being opened.
However, any fridge has no “normal” cycle rate because of all the factors affecting the temperature inside.
Calculating Your Power Requirements for an Engel
For most campers/road-trippers/off-grid enthusiasts, a 40-liter Engel will provide more than enough space for cold goods, and this is the most widely used model. As a result, so for the sake of brevity, we’ll be focusing on this fridge size for the bulk of this article.
The first thing you’ll need to consider — before your panel— is the battery you’ll be using to run your fridge.
You can choose between running your fridge with a separate auxiliary battery(highly recommended) or hooking up your panel and fridge to your car battery.
A separate battery used solely for your fridge is the best bet, as this will extend your battery’s life and avoid getting stuck with a flat car battery.
Also, having a separate battery/panel setup for your fridge will make it a lot more versatile. For a 40L Engel fridge, a single 100AH battery should do the trick.
How long will a 100AH battery run an Engel fridge?
The most commonly used lead-acid batteries nowadays have a 100 amp hour rating (AH), so we’ll use this for the following examples.
Since they have a depth of discharge(DoD) of 50%, you’ll be able to get 50AH from them before they need recharging.
Naturally, the larger the battery you use, the longer you can run your fridge, but you’ll then need a larger panel to charge it too.
- For example, let’s say your 40L fridge is running at a maximum power draw; 2.7 amps. This will mean that your fridge will be able to run off the 100AH battery(50AH DoD) for roughly 18 hours, or 70 hours at the minimum draw of 0.7 amps.
Of course, neither of these are real-world metrics as your fridge is subject to a variety of fluctuations (ambient temperature, opening, and closing, thermostat setting, etc).
In good ambient conditions, you can expect your fridge (not freezer) to draw around 1 amp per hour, or 12 AH per 12 hours.
Running it at the freezer setting will naturally give you less than that, around 25%, due to the compressor working so hard.
How many watts does a 40L Engel fridge use?
When calculating the wattage usage of your Engel fridge, it’s important to note that watts refer to “real power” consumption while volts and amps refer to “apparent power.”
This can be difficult to calculate since the AH draw of your fridge is variable depending on the compressor.
The transformer inside your Engel fridge is running at 12 volts, so the simple calculation of volts multiplied by amps will give you your rough answer.
So, at the highest draw of 2.7 amps per hour at 12 volts, your fridge will draw roughly 30-32 watts per hour, maximum.
How much power does a 60L Engel fridge draw?
According to the Engel website, a 60L Engel will draw 0.5–4.2 amps per hour, almost double that of a 40L fridge at its maximum.
At a maximum draw of 4.2 AH, your fridge will be drawing around 50 watts per hour.
If you are using a 100AH battery, you’ll have 50AH DoD at your disposal, which at the maximum draw, your 60L Engel will use in 12 hours, or 25 hours at the minimum draw.
Even in ideal, sunny conditions, a 100-watt panel and 100AH battery would not be enough to power a 60L Engel, and you are far better off with at least two 100AH batteries.
Calculating Panel Sizes
When deciding on a panel size to run your fridge, you’ll want to go for a panel larger than your calculated needs in ideal conditions.
So, back to our example of a 40l Engel drawing 12 AH per 12 hours.
If you are running your fridge off a 100AH battery, you’d need a panel of at least 100 watts in ideal conditions.
It’s important to remember that no solar panel is 100% efficient, so you’ll be charging at 85% efficiency at best.
Will a 100w solar panel run an Engel fridge?
As a general rule, a 100-watt, 12-volt panel running at the general efficiency of 85% (or 85-watts) would charge a 100AH battery in ideal conditions in a little over 14 hours.
This means that from flat (50% DoD) to full again, you’re looking at around a day and a half of sunlight.
Of course, this is the best-case scenario in almost constantly sunny conditions, which most of us do not have the benefit of.
Your 100AH battery will be drained by your fridge at a rate of around 24AH every 24 hours, of which your panel will only be recharging for half the time (during the day).
(100-watt solar panel)
In ideal conditions, your panel will be charging your battery at a rate of 1–4 amps per hour, so you’d be recharging your battery at roughly 10-50 amps per day.
If your fridge is using an average of 12AH per day, a 100AH battery with a 100-watt panel is certainly enough on paper, but in a real-world scenario, you’ll need more.
Remember that your fridge will draw more power depending on the ambient conditions and the thermostat settings, and so could theoretically draw up to 40AH per day, almost running your battery to its maximum DoD —every day.
Even in the best conditions, this will put a lot of pressure on your battery.
What size solar panel is best for a 40L Engel fridge?
Ideally, you’ll want a panel of at least 150-200 watts to make sure you never run out of power. This will factor in overcast days for charging and your fridge running at a high power draw.
Running a 200-watt panel charging two 100AH batteries is the ideal scenario, as it will then be highly unlikely that you’ll run out of power.
(200-watt solar panel – Bluetti)
At a minimum, a 100-watt panel charging a single 100AH battery will work, but your setup will constantly be working at its maximum capacity.
Remember — if you run your Engel fridge-freezer on the coldest or “freezer” setting, you can expect to use around 25% more power overall.
What size solar panel will run a 60L Engel fridge?
If you are looking to run a larger fridge, for example, a 60 or 80-litre fridge, you’ll naturally need a larger panel and more battery power.
A 60L Engel typically draws 0.5–4.2 amps per hour or roughly 2.5 amps per hour on average.
(300-Watt Solar Panel – AcoPower)
This would mean it will need 60AH on average over a 24-hour period, so you’ll need at least two 100AH batteries to run it, in which case you’ll have 100AH of power at your disposal.
Your batteries will need to be charged by a panel of at least 200 watts, preferably more, to keep up with the power demands of your fridge.
Engel Battery and Conclusion
If you are running a 40-liter Engel fridge-freezer, you could feasibly get away with using a 100-watt panel — but this would only work under ideal, sunny conditions.
The best size would be a 150-200 watt panel with two 100AH batteries, as this would provide more than enough power even under less than ideal conditions, plus it would not put much stress on your solar system.
With any solar setup, the golden rule is to have at least 25-50% more power than you need on paper. With this in mind, we highly recommend a panel of at least 150 watts to run an Engel fridge-freezer.