Solar panels are among the fastest growing forms of renewable power, and a great investment overall. 300-watt solar panels are one of the most common additions found in RVs and often come already installed.
But what can a 300-watt solar panel run, exactly?
Let us guide you through the ins and outs of solar systems found in RVs, including how to calculate your total power usage. Let’s get started!
Your RV solar power system is made up of several key components, as follows:
All these components work together to collect, regulate, store, and deliver power to your RV appliances. Many of these parts may be purchased separately or in full sets.
So how does the solar power in your RV work, exactly?
When sunlight strikes the solar cell’s surface, a charge carrier of electrons and holes are created. The internal field that’s produced would then separate some of the positive charges (holes) from negative charges (electrons).
Once the charges are separated, the circuits are passed and stored into the battery. This allows you to operate your machine even when the sun goes down.
The batteries in these solar cells would produce enough power to run DC (direct current) equipment. However, as DCs flow in only one direction, it’s used to only power low-voltage equipment.
To power high-voltage equipment, a system called solar photovoltaic is required, which is found in an inverter. Inverters change power from DC to AC (alternating current), which is what powers blenders, refrigerators, air conditioning, etc.
In summation, the solar power in your RV works this way:
Sunlight hits the solar panels → electrical current is created → electrical current feeds into a charge controller charge → controller goes through the battery → batteries produce DC power → inverter changes the power from DC into AC power.
If your solar panel is under direct sunlight for an hour, it will generate 300 watt-hours of electricity. 300-watt panels produce 240 volts, which equates to approximately 1.25 Amps.
However, a solar panel’s efficiency isn’t always 100%. Wattage is assigned according to each panel’s peak capacity for generating energy during optimal circumstances in laboratories, also known as STC (Standard Test Conditions).
But in the real world, you can expect a drop in performance. This is what’s referred to as PTC, or PVUSA Test Conditions. PTC ratings are more important than STC ratings when evaluating solar panels as it’s recognized as a more realistic measure of PV output.
A solar panel’s output is controlled by a number of variables. To determine the amount of electricity produced by a solar panel, you’ll need to consider the following:
The energy output of the sun often isn’t steady throughout the day, even during bright sunshine hours. It’ll produce less in the mornings and in late afternoons compared to mid-afternoons, where the sun is directly falling into the panels.
Solar panels won’t produce as much electricity when the sun is at an angle. Peak sunlight hours are generally between 9 AM and 4 PM.
Compared to Winter and Fall, the sun’s position during Summer and Spring allows for more power to be generated.
You can visit the National Renewable Energy Laboratories (NREL) to find the sun’s peak hours in your area. All you’ll need to do is to type in your address, or the location you’ll be taking your RV, and it’ll tell you exactly when it will be.
You can even download a copy of the file they’ll create for you, free, as a reference.
The make and model of your solar panel will have its efficiency rating listed. Solar panels with high-efficiency ratings convert more usable electricity compared to models with low-efficiency ratings.
The greater the efficiency, the less surface area is required to meet your energy requirements. But, of course, it’ll come with a higher price tag.
Standard solar panels have an efficiency rating of 15% and 20%. Some modules exceed this written percentage, especially if they’re made of higher quality.
Under the same conditions, a panel of an efficiency rating of 20% will produce 33.3% more kilowatt-hours (kWh) than that of 15%.
The way the panels are installed is crucial to getting the optimal energy output.
Shades of any type may disturb the output of solar panels, whether it be from cloudy days or overhanging tree branches. As the cells are linked together, shade on one cell directly affects the efficiency of the rest.
Like everything ever made, the more your panel ages, the more the overall system efficiency depreciates.
Most home solar panels have power output ratings ranging from 250 to 400 watts, with 400 watts being the highest available for RVs.
A 300-watt solar panel is considered to be one of the higher power scales and generally are quite powerful. They’re also manageable and come at an attractive price. This is why 300-watt solar panels are often bought by those who have RVs, vans, or boats.
300 watt solar panels are big enough to power a full home use. It’s important to note, however, that solar modules aren’t always 100% efficient. Realistically, it’s more about 85%, which makes your wattage around 255 Watt. This means you can run appliances up to 250 watts during the day.
Here are some examples of what ~300-watt solar panels may operate:
To calculate how much solar power you need, you’ll need to first write down every appliance you’d like to use in your RV with your solar set up. Once you’ve done so, you’ll need to find out how much wattage every appliance uses by the hour.
If you’re not quite sure what your appliance’s watt power is, you can use a Wattmeter that can be bought in any electronic store.
Simply unplug your electronic device from your wall or power strip and replace it with the wattmeter. Once your wattmeter is plugged in, you can go ahead and plug in your electronic device and it’ll start its calculations.
When you’ve written everything down, you’ll now be able to calculate your watt usage on a given day. Use this simple equation: watt x hours/day.
For example, if you’re running a laptop for 4 hours a day, and its watt usage is 90W, your total watt is 360.
If you’re using it only for a few minutes, for example a coffee pot, you’ll need to divide the minutes to 60 (as there are 60 minutes in an hour). If your coffee pot has a wattage of 600, you’ll be multiplying 600 with 0.17, which equals to 102W.
Add the total number of watt usage you have for all the applications in your RV. This will allow you to determine what solar panel you need, or if your existing panel is sufficient.
You also need to take into consideration the power that’s inverted from DC to AC as you calculate the wattage.
Some devices pull in a surge of power at start up, like air-conditioners and refrigerators. AC devices draw about 10-15% more energy than what the actual it actually requires.
If you’re not too fond of manual calculations like I am, you can instead use an online watt calculator.
To avoid calculations altogether, you can instead ask yourself what type of camper you are. We’ve split these categories into three parts to make it a bit easier.
For those who just need to power DC appliances such as LED lights, fans, and charge small electronics while camping, you’ll only need a low-power solar system of 100W.
If you’re looking to watch TV, run coffee makers, and power other AC devices for a few hours at a time, a medium power solar system of 250-300W is your best choice.
If you’re looking to use a large amount of power and operate multiple appliances for long periods at a time, you’ll need an extreme solar kit of 400W.
There are a variety of RV solar panels out there, each with their own unique pros and cons.
In the RV world, you’ll find three types of solar panels.
These panels are made from individual cells of thin wafer-like silicon crystal. They’re often thought of as a premium solar product because of its high efficiency and great looking aesthetics.
Mono-Crystalline panels come with the following features:
Poly-Crystalline, also known as Multi-Crystalline, are solar panels that consist of several smaller silicon crystals in an individual PV cell. Because they’re made up of multiple photovoltaic cells, each cell functions as a semiconductor device.
Poly-Crystalline solar panels are more ecofriendly than Mono-Crystalline panels because of the silicon that’s used during production. They’re also much cheaper than the aforementioned panel.
Poly-Crystalline panels come with the following features:
The only downside to this solar panel is that it has a lower heat tolerance compared to Mono-Crystalline. When faced with higher temperatures, they’re not as efficient.
Amorphous solar panels are constructed of thin-film silicon panels that are attached to a backing material. This enables solar panels to be more flexible and lightweight.
Compared to the other two panels, Amorphous solar panels require twice as much surface area just to get the same output as a monocrystalline panel.
Amorphous solar panels have an efficiency rate of ~7%, while mono- and poly-crystalline panels range anywhere between 14% to 20%+.
Amorphous panels come with the following features:
Now that we know the difference between the three, what’s the best solar panel? The answer depends on what best fits your needs.
Amorphous panels are the cheapest, but they’re twice the size of poly and mono-crystalline. Mono-crystalline is highly efficient, but also the most expensive.
Poly-crystalline is a balance between the two; they take up half the space of Amorphous panels, produce slightly less power than mono-crystalline panels but more than Amorphous panels, and are greatly affordable.
The choice rests on your hands!
While RV solar panels aren’t always necessary, they boast a ton of benefits. Not only do they help extend your RV’s battery life and cut down on the use of generators, but they also save you money in the long run.
Here are some other benefits of using a solar RV.
A 300-watt solar panel can run a multitude of appliances. They’re the “sweet spot” of RV owners; they’re not too expensive, and they produce just enough power to run almost all your RV appliances.
As long as you position your panels right, you’ll be able to enjoy all the benefits a solar panel brings!
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