How Big Of A Solar Generator Do I Need?

When the power goes out, we want to have a source of back-up power. Food needs to stay cold, and our devices need to be charged. You might not have access to fuel in an emergency, but you always have the sun. So how big of a solar generator do you need? 

The size solar generator you should have is determined by your needs. A small generator (under 1,000 watts) will power small appliances like laptops, phones, and lights. Generators between 1,000 watts and 3,000 watts can power larger devices such as a refrigerator or microwave. Powering an entire house requires larger solar generators with over 5,000 watts of power.    

A solar generator is quiet, doesn’t require gas, and is almost maintenance-free. However, the market is full of generators, and many manufacturers boast that their generators can power your home in an emergency. Read on to learn what a solar generator can actually do.

What Is A Solar Generator?

First things first—the term “solar generator” is misleading because it does not generate energy. A traditional generator uses fuel—gas or diesel—to create energy. It converts the energy from the gas into electrical energy through an engine that powers a turbine.

A solar generator doesn’t generate the energy — the sun does that. It does not capture the energy either — the solar panels do that. Nor does it need solar panels since most portable units can be charged via a house or car outlet.

Instead, the generator contains batteries that store the energy.  So why isn’t it called a battery?  

Along with housing a battery, a solar generator also contains an inverter, charge controller, and battery monitor, each with a specific function:  

  • The inverter changes the energy to alternating current.
  • The controller regulates the current and voltage.  
  • The outlets let you plug in your appliances and devices.

Some prefer to call them a power station, but it is most commonly called a solar generator. Here are the best reviewed solar generators for your home or RV.

Types of Solar Generators

Solar generators broadly fall into one of two categories—back-up and portable. Let’s examine the advantages and disadvantages of each type before going into the specifics.

House Back-Up Solar Generators

Generators to back-up a house are large units with enough juice to power many appliances in your home. Because they are not gas-powered, solar generators can be stored and used inside. Their large size lets you power more appliances for a longer time.

There are several disadvantages to the largest units:

  • Size. Units this size are bulky and not designed to be portable.  
  • Price. Large generators contain numerous batteries, increasing the price substantially. You can easily spend upwards of $5,000 for a 3000-watt system, before labor.
  • Installation difficulties. Installing a generator to power appliances such as water heaters or heating or cooling systems requires qualified electricians to modify or replace electrical panels. If you already have a system and use net-metering, then you will be required to have a transfer switch so that power from your system does not enter the grid.

Large, whole house solar generators are significant investments. Consult with a solar expert to find out what it would take to install a whole house generator.

Portable Solar Generators

Smaller solar generators are less expensive, can be moved, and will power several appliances. They require little maintenance, and an electrician is not needed for installation. Think of them as plug-and-play devices that will keep your phones charged, give you some light, and power a few appliances.

These generators can also be used in non-emergency situations. Outdoor uses include camping, boating, and RVs.  

Solar panels for portable generators are smaller than those for rooftop installation. Lugging solar panels around is unnecessary for a camping trip, as many portable chargers can be plugged into a car charger.

To pick a solar generator that is right for your needs, ask yourself these questions.

How Much Power Do I Need?

When purchasing any generator, you need to decide what your power needs will be. Do you want to power your devices and a few lights? Besides keeping your refrigerator running, do you also want to use a microwave or power up some tools?  

Plan Out What You Need

Planning out what you need is a three-part process:

  1. Decide what you want to power.
  2. Know how much energy your appliances use.
  3. Figure out how much power the generator will provide.

Let’s investigate each of these in more detail.

Know How Much Energy Your Appliances Use

First, make a list of all the appliances you would like to use. Only include those that can be plugged into a regular household outlet. Appliances like water heaters that are wired directly to a fuse box will not work. Neither will something like an oven that needs a 220-volt outlet.

If air conditioning or heat is essential due to your location or a medical condition, consider buying a small a/c or portable heater.

After making your list, the next thing you need is the power requirements for the appliances. This information is listed on the appliance, usually in watts. If the equipment lists just the amps, multiply that amount by the voltage. A small space heater that runs on 120 volts and draws 12.5 amps uses 120 x 12.5 or 1500 watts.

Next, decide how long you plan to use each device. For example, you might want to use three 60-watt light bulbs, but only in the evening. So then multiply the total watts times the number of hours to get the watt-hours.  

In this case, 3 x 60w = 180 watts, and 180 x 4 hours equals 720 watt-hours per day.

Find Out The Watt-Hours Of The Generator

Knowing how many watts your devices will use tells you how many you can run at one time. Let’s say you plan to use a 700-watt refrigerator and want to cook a meal in a 1,500-watt microwave. A 500-watt generator would not be able to power either one, and a 2,000-watt generator can do one or the other but not both at the same time.

Watt-hours is a measure of how long a generator holds a charge measured in hours. The 700-watt refrigerator constantly running uses 700 watts per hour. A generator with a battery capacity of 7,000 watt-hours could run a continually running refrigerator for 10 hours before the battery is drained.

Luckily, a refrigerator does not run continuously. To get an approximate run time for an appliance that does not run continuously, divide the amount of energy it uses in a year by 365, and you will know how much it will use in a day.  

Combine Wattage And Watt-Hours

In preparing for a situation where you need a generator, it’s best to over-prepare. If you buy a system that could run a few essentials for 24 hours, but the skies are overcast for two days, your battery will drain, and your food will go bad. Plan for 2-5 days with insufficient light to be on the safe side.

How Big Of A Solar Generator Do I Need?

Now that you know how much wattage you need from your solar generators, it’s time to size your generator. So what size solar generator do you need? Here are options based on three types of appliances that you’d like to power.

Small Appliance Solar Generator

This bucket is useful if you would like to power smaller devices for a couple of hours per day. Many of these appliances use less than 100 watts of solar. Some examples of these appliances include:

  • Cell phone or tablets
  • Laptop computers
  • Modems and routers
  • LED lights
  • Small TVs (under 45 inches)
  • Mini refrigerator

For these appliances, a 300 watt solar generator will provide enough power for several hours. You will need to charge it with either solar panels, a wall outlet, or your car. This makes it a great option for camping or providing solar power to your RV. We recommend using the 100 watt portable solar panel to charge the solar generator.

Critical Appliances Solar Generator

You will want this medium-sized solar generator for emergency scenarios. It could be a small power outage from a storm or hurricane. Or a tree fell on a power line cutting power to your house for half a day. Here’s a list of appliances this solar generator can power:

  • Refrigerator
  • Smaller air conditioning units
  • Some medical equipment
  • Emergency lights
  • Larger TVs (Over 45 inches)
  • Pellet grills

A slightly larger solar generator, like the 1000 watt Jackery Explorer, works best for these appliances. It can power refrigerators during small power outages. It can also be used for camping to power your pellet grill while powering your football game on the TV. You will need to have solar panels to charge the solar generator. We recommend using a portable 100 watt solar panel.

Entire Home Solar Generator

Powering your entire house would require a larger solar battery system that includes an inverter and charge controller. But you could get away with powering most of your house through a series of larger solar generators. They can be used in parallel with each other. And you could plug certain appliances into different generators.

We recommend using the Goal-Zero 2000 watt solar generator. It can be used to power smaller homes by itself. Larger homes can use two or three of these to power the most important appliances, lighting, and air conditioning. The manufacturer recommends powering it from your house or through 600 watts of solar panels. You may need to power it from your house if you would like to use it during a storm. Solar panels are ineffective without sunlight.

Features To Look For In A Solar Generator

Once you have calculated your essential power needs, it is time to look for generators. Since a solar generator has several components, you need to also investigate those.  

  • Battery. We have already discussed that your battery needs to have enough watt-hours so you can use the generator when it is dark, when sunlight is limited, or when you are using more power than your panels are bringing in. Look for at least 2,000 watt-hours if you plan to use the generator for back-up power for a house.  
  • Solar Input. The more energy the generator can take in, the quicker it recharges. If it inputs 200 watts an hour, then it needs 10 hours of sunlight to fully charge. Between assuming you didn’t drain your battery and you probably will not get 10 hours of maximum sunlight, 200-watt input should be the minimum.
  • Charge Controller. Solar generators come with one of two types of charge controllers—Pulse Width (PWM) or Maximum Power Point Tracking (MPPT). An MPPT controller increases a generator’s efficiency by up to 40%, so opt for one that uses an MPPT.  
  • Inverter. If you plan to expand your system in the future, you should buy an inverter to handle additional watts. A 600-watt inverter will never be able to run more than 600 watts, and inverters cannot be upgraded.

Bottom Line

If the power goes out, having a generator can be a lifesaver. A solar generator does not require fuel, is quiet, and can be used indoors. Portable generators are not powerful to power an entire house, so you will have to plan out what appliances are essential.  

If nothing else, look for two numbers—the watts it can handle at one time, usually in the name, and the watt-hours.    



I'm trying to make the world a bit greener every day, whether that's through my day job or helping others make green choices for their homes.

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