FAQ: How Many Solar Panels Do I Need to Run A Fridge? - Goldin Solar, LLC

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People often ask how many solar panels are needed to run a fridge or other common Florida appliances like microwaves, air conditioners or pool pumps. This post aims to give you a good idea of how many panels you’ll need for a few of the most common appliances in your Florida home or RV. You can also find an equation used to calculate how many panels you will need to power any appliance.

How To Calculate How Many Solar Panels You Need

To determine how many solar panels you need to power something, it’s important to understand the basics of how solar works.

First, solar panels only produce power when the sun is shining. If you want solar to power your appliances when the sun isn’t shining, you either need energy storage (usually a battery like a Tesla Powerwall) or you need to trade energy credits with your utility through net metering. We will assume you have such an arrangement and can save your solar energy for later to power appliances at night. 

A typical roof-mounted solar panel (3’4” x 5’8”)  will produce about 250 watts DC at peak operating conditions. We generally assume that, accounting for efficiency losses of the inverter system, a solar panel can produce four hours of peak production per day. Thus a typical solar panel connected to an inverter will produce 1 kWh of energy per day (250 watts*4 hours of peak production). 

Some appliances are run continuously (air conditioners, refrigerators) and others only for a short time (dishwashers, microwaves). To find how much energy they use in a day, we multiply their wattage by the amount of time they are turned on, in hours. This gives us a result in watt-hours which we divide by 1,000 to get their energy requirement in kWh per day (some appliances, like the fridge below, tell us their estimated usage in kWh per year. We divide by 365 to find its usage per day). 

Finally, to calculate the number of panels needed to power that appliance for its daily usage, we divide by 1 since each panel is producing 1 kWh per day. 

Now we are equipped to determine how many solar panels are needed to power common appliances in Florida and beyond. 

How Many Solar Panels Are Needed to Run Common Appliances:

How many solar panels do I need to run a fridge?

This fridge takes about 399 kWh to run for a year. Each panel can produce 1 kWh per day. Thus you need 1.1 solar panels to run a fridge.  

How many solar panels do I need to power an air conditioner?

This window AC unit takes 450 watts. Powering this air conditioner for 24 hours per day requires 10.8 solar panels. Powering an air conditioner for 8 hours per day requires 3.6 solar panels. 

How many solar panels do I need to power a space heater?

This space heater takes 750 watts on low power. It takes 18 solar panels to run this space heater continuously. 

How many solar panels do I need to power a pool pump?

A 1.5 horsepower pool pump consumes 1180 watts. It takes 28 solar panels to run a 1.5hp pool pump continuously. However, pumps have starting loads much higher than their operating loads, so 28 panels will not be sufficient to turn the pump on.

How many solar panels do I need to power a microwave?

A microwave typically consumes 1,000 watts. If you use the microwave for 10 minutes per day it will require 0.17 solar panels.

How many solar panels do I need to power a blender?

A blender uses 500 watts. If you use a blender for 5 minutes per day you need .04 solar panels.

How many solar panels do I need to power a coffee maker?

A coffee maker uses 1,000 watts. To use a coffee maker for half an hour a day you need 0.5 solar panels.

How many solar panels do I need to do laundry?

A clothes washer takes 800 watts and a dryer takes 3,000 watts. If you run them each for 1 hour per week you will need 1.1 solar panels. 

How many solar panels do I need to run a dishwasher?

A dishwasher uses 1,300 watts. To run a dishwasher for an hour per day you need 1.3 solar panels.

How About Powering My House, RV, or Battery with Solar?

People also wonder about powering entire systems with solar panels. Next, we will consider how many solar panels you need to power houses, RVs, and batteries.

How many solar panels do I need for a 1,000 square foot home?

The average home in the United States uses 750 kWh per month and will need about 25 solar panels to meet its energy needs.

But, it’s not that simple. The square footage of your home is not the most important factor when it comes to your energy use. Other factors to consider include your home’s efficiency and your consumption habits. The best way to determine how many panels your home needs is to get a quote from a provider in your area. A provider will look at your last year’s energy bills to see how many kWh you use in a typical month. Then they will use software (we use Helioscope) to determine the solar exposure of your roof and calculate more accurately how many panels are needed and where they should be placed to meet your energy needs. 

To get a rough estimate instead, you can divide your monthly kWh usage by 30, since each panel can produce about 30 kWh per month. However, this is not an exact estimate because it will not take into account your local solar exposure, weather conditions, and other factors like the angle of your roof. 

How many solar panels do I need to power my RV?

The peak load an RV is expected to consume is 2 kW. However, assuming you aren’t running all major appliances at once, you can probably assume it uses about 500 watts at any one time. To keep this power maintained 24/7, you will need 12 solar panels. However, the details of RV power systems, startup power, and battery power mean that it isn’t quite as simple as just getting 12 panels for the RV. You can learn more about powering an RV with solar here

How many solar panels are needed to charge a 12-volt battery?

Charging a battery is slightly more complex than using solar to power an appliance. To charge a battery with solar requires a device called a charge controller which is connected between the solar panel and the battery. The charge controller monitors the charge of the battery and the output voltage of the solar panel and adjusts voltage to charge the battery efficiently and safely. 

The length of time to charge a battery will also depend on the storage capacity of the battery. A 12-volt battery can be small enough to fit in your pocket or the size of a car battery. While they provide the same voltage, they are capable of doing so for different lengths of time. The storage capacity of a battery is generally measured in Ah. Many 12-volt batteries are rated 100 Ah. A 12-volt, 100 Ah battery can store 1.2 kWh of energy. Thus, based on the calculations and assumptions outlined above, such a battery would require 1.2 solar panels to charge over the course of a day. With more panels, the battery will charge more quickly.

The Equation to Calculate How Many Solar Panels You Need for an Appliance

You can calculate the number of panels needed to power an appliance using the following formula:

number of panels = appliance wattage*hours running the appliance/1000

Find your appliance’s wattage by checking its spec sheet, looking on the label, or looking up the average for its type in this table of appliance and tool wattages

Learn More About Solar:

Learn if solar is right for your home

The basics of solar in South Florida

The complete guide to solar risk and return in Florida

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