RV solar sizing is an important consideration for those who want to travel off-grid with their RV. One of the key factors in determining the size of a solar system is estimating the electrical usage of the RV. There are several ways to estimate electrical usage, each with its own advantages and disadvantages.
- Use a kill-a-watt meter
- Calculate device consumption and usage (with spreadsheet)
- Measure battery voltage
For an overview on RV solar sizing check out our post What Size Solar System is Right for my RV?
Understanding Why We Need RV Solar Sizing
RV solar sizing is an important aspect of designing a solar power system for your RV. It involves determining the size of the solar panels, battery bank, and inverter required to meet your electrical needs. In this section, we will discuss why RV solar sizing is important and the factors to consider when sizing your RV solar system.
Why is RV Solar Sizing Important?
RV solar sizing is important because it ensures that your solar power system is capable of meeting your electrical needs. If your system is undersized, you may not have enough power to run all of your appliances and devices. On the other hand, if your system is oversized, you may end up spending more money than necessary on equipment that you don’t need.
Factors to Consider When Sizing Your RV Solar System
When sizing your RV solar system, there are several factors to consider. These include:
- Electrical Usage: The amount of electricity you use each day will determine the size of your solar panels, battery bank, and inverter. To estimate your electrical usage, you can use a power meter or look at your past energy bills.
- Location: The amount of sunlight your RV receives will affect the size of your solar panels. If you travel to areas with less sunlight, you may need larger panels to compensate.
- Battery Voltage: The voltage of your battery bank will determine the size of your inverter. Most RVs use a 12-volt battery bank, but some may use a 24-volt system.
- Climate: The temperature and climate of your location will affect the performance of your solar panels. In colder climates, you may need larger panels to compensate for reduced efficiency.
- Power Draw: The amount of power your appliances and devices draw will determine the size of your battery bank. To estimate your power draw, you can use a power meter or look at the specifications of your appliances and devices.
Three Ways to Estimate Electrical Usage
When sizing an RV solar system, it’s important to know your electrical usage so you can determine how much power you need to generate. Here are three methods to estimate your electrical usage:
Method 1: Use a Kill-A-Watt Meter
A Kill-A-Watt meter is a device that plugs into an outlet and measures the power consumption of the device that’s plugged into it. To use this method, simply plug your RV appliances into the Kill-A-Watt meter and record the power consumption over a period of time. You can then use this data to estimate your daily power consumption.
Method 2: Calculate Device Consumption and Usage (with Spreadsheet)
This method involves calculating the power consumption of each RV appliance and estimating how long you use each appliance per day. You can find the power consumption of each appliance on its label or in the owner’s manual. Once you have this information, you can use a spreadsheet to calculate your daily power consumption. Be sure to include all appliances, including lights, fans, and electronics.
Math Formula you Should be Familiar With
There is a formula that you’ll need to get all your devices into watts, it’s Watts = Volts x Amps.
You’ll need to find the watts of each device, watts is a measurement of electrical power we can use to estimate the size of our battery bank and solar system. If your device doesn’t show the watts, you’ll need to look for the volts & amps to then calculate the wattage using the formula above.
Here is a spreadsheet to help. Or go here and copy the document to use it on your own. Wattage Calculator Spreadsheet
Method 3: Use an Online Calculator
There are several online calculators available that can help you estimate your RV electrical usage. These calculators typically ask you to input the number and type of appliances you have, as well as how long you use them per day. The calculator will then estimate your daily power consumption based on this information.
GoalZero has a basic calculator that can come in handy – https://www.goalzero.com/pages/wattage-calculator
No matter which method you choose, it’s important to be as accurate as possible when estimating your electrical usage. This will ensure that your RV solar system is sized correctly and can provide you with the power you need while on the road.
Determining Your RV Solar System Size
When it comes to RV solar sizing, it’s important to determine the right size for your RV solar system to meet your electrical needs. Here are four sub-sections to help you size your RV solar system.
Calculating Your Daily Energy Usage
To calculate your daily energy usage, you need to know how much energy each of your appliances uses. You can find this information on the label of each appliance or in the owner’s manual. Once you have this information, you can use a spreadsheet or an online calculator to add up the total energy usage for each appliance. There are resources above to help you out. This will give you an idea of how much energy you need to generate each day.
Sizing Your Solar Panels
The size of your solar panels will depend on your daily energy usage. A general rule of thumb is to install enough solar panels to generate 1.5 to 2 times your daily energy usage. This will ensure that you have enough energy to power your RV even on cloudy days. You can use an online solar panel sizing calculator to determine the right size of solar panels for your RV.
You can also take the total wattage calculated from one of the methods above and divide that by the total amount of direct sunlight you estimate to received. If you live in a cloudy areas and get 8 hours of sunshine, you likely get 4 hours of direct light. Say for instance you live in Michigan and the days are 10 hour long sunny days (in the summer). Michigan is very cloudy so you should estimate between 4 and 6 hours of good sunlight for those days. Winter time in Michigan will be a whole new calculation as it’s very cloudy with short days.
Once you have the total wattage and your hours, divide the total wattage by hours. Total Watts / Hours of Sun = Solar panel wattage. Say you need 1000 watts of power for a 24 hour period, and you get 5 hours of good direct light. 1000 / 5 = 200 Watts.
SIDE NOTE: Understanding how much good sunlight is critical. But if you can’t, tack on an additional 20% to what you estimate. So 200-watts would be 240-watts, etc. Then round up for solar sizing from there.
Sizing Your Battery Bank
Your battery bank should be large enough to store the energy generated by your solar panels. The size of your battery bank will depend on your daily energy usage and the number of days you want to be able to go without charging. A general rule of thumb is to install a battery bank that can store at least two days’ worth of energy. You can use an online battery bank sizing calculator to determine the right size of battery bank for your RV.
Batteries are sized in amps. It’s common to simply use your daily wattage calculation, double it, and divide it by 12 (volts) for the total amps needed. So if you need 1000 in a 24 hour period you would use 2000-watts, and divide by 12 (volts). 2000 / 12 = 166 amp battery at the least, I would just say go with 200 amp-hour battery bank.
SIDE NOTE: If you have a 24-volt battery system you’ll want to use 24-volts for your calculation. You will also need to have many other different devices to charge and use the power from this bank. It’s a whole new topic.
Dive Deeper Into Batteries with our Battery Basics Guide
Sizing Your Charge Controller
Your charge controller is responsible for regulating the amount of energy that flows from your solar panels to your battery bank. The size of your charge controller will depend on the size of your solar panels and battery bank. A general rule of thumb is to install a charge controller that can handle at least 25% more current than your solar panels can generate. This will ensure that your charge controller can handle the maximum amount of energy generated by your solar panels.
By following these four sub-sections, you can determine the right size of RV solar system to meet your electrical needs.
RV Electrical Usage Guides the Whole System
It is important to estimate an RV’s electrical usage for an RV solar panel system because it helps determine the number and size of solar panels needed to power the RV’s electrical needs. Without an accurate estimate of electrical usage, the solar panel system may not be able to provide enough power to meet the RV’s needs, leading to battery depletion or the need for a backup generator.