Off-grid solar: Costs, process, and best products in 2023

Going off-grid isn’t cheap. An off-grid solar solution might be practical for property owners with unusually low electricity loads. However, for most solar shoppers, going off the grid with solar is a much more involved and expensive process than you might initially think.

Going off-grid with solar requires more than installing solar panels and disconnecting from your electric utility. Costs, physical space constraints, and energy-hungry habits can make going off the grid daunting. There are four key steps to determine if going off-grid is feasible for your home, as well as how much it will cost:

1. Calculate how much electricity you use;
2. Determine how many solar batteries you will need;
3. Design a solar panel system to fit your needs;
4. And add up the costs of the combined solar plus storage system.

How much electricity do you use?

The first step in going off-grid is understanding how much electricity you use, also called your consumption or electricity load. To determine how many solar panels and solar batteries you need to go off-grid, you need to know how much electricity your home uses daily.

There are two primary ways to calculate your home’s daily electricity needs. The first and easiest is to find the monthly consumption number on your electric bill (expressed in kilowatt-hours, or kWh). To get daily electric consumption, divide your monthly usage by the number of days in the month. Since use can vary monthly, performing this calculation for multiple months is a good idea.

The second method for calculating your daily electricity load is a “bottom-up” approach: multiply the wattage of each appliance in your home by the number of hours you use it every day. Though you may not be able to find the specific wattage for all of your appliances, most large household electronics – like TVs or refrigerators – come with a yellow Energy Guide sticker that estimates yearly energy use. Divide that number by 365 to get these appliances’ estimated daily electricity load.

One of the best tools available for estimating energy use is the Department of Energy’s calculator. Based on that calculator, here are some estimates for the electric load of common appliances:

The above approach is a great way to review your historical energy usage, though it may not be as helpful to forecast future energy consumption. The second approach, on the other hand, is better at predicting what you may use in the future. Both of these approaches are estimates. If you’re planning to install solar and storage to go off-grid, it may be worth purchasing a home energy monitor or an energy management system to get a more precise estimate of your electricity usage.

How many batteries will you need?

To go off-grid, you need a way to store the electricity produced by your solar energy system at times when you’re not using it. Not every solar battery can operate independently of the grid, even if you feed it solar energy: You specifically need a battery that can “island” or form its own grid so that the panels will recharge the battery daily without a grid connection.

To determine the number of batteries you need to power your house for a single day, you need to know your daily electricity consumption and the amount of electricity stored in a standard solar battery.

The amount of electricity stored in a battery is called the “Usable Energy,” expressed in kWh. This is the amount of electricity you can get out of a battery after accounting for electrical losses and any energy needed to power it.

With these two data points in hand, calculating the number of batteries you’ll need is straightforward. For instance, the average American household uses about 30 kWh per day. Given the conversion losses associated with storing electricity, you’ll need enough batteries to store slightly more than what you use per day, likely closer to 32 kWh, depending upon the efficiency of the battery you select.

Two of the most common solar batteries are the Deep Cycle Batteries and the energy storage packs.

This is just the number of batteries you’ll need to power your house for a single day. In reality, you’ll want enough backup storage capacity to power your home for many days, or even an entire week, to ensure you still have electricity if you have a period of inclement weather or need more than your average daily usage in a single day.

How many solar panels will you need?

Next, you’ll want to design a solar energy system that’ll supply electricity to your property and a storage setup large enough to fill your battery every day.

The electricity your solar panel system produces directly results from the amount of sunlight your panels receive. The average home in the U.S. gets an average of 5 sun hours per day, which doesn’t represent the amount of time your panels are in the sun but instead measures the number of hours during which sunlight intensity is 1,000 W/square meter. Learn more about what your average sun hours are depending on your state. Other factors like shade and the angle of your panels relative to the sun also affect the electricity your panels produce.

To determine how many solar panels you need to fill your batteries every day, divide the amount of electricity required (in this case, 32 kWh) by the number of expected sun hours (5 in this example):

32 kWh / 5 hours = 6.4 kW

Thus, we need a solar panel array of about 6.4 kilowatts to fill up a battery bank with a capacity of 32 kWh daily.

The number of solar panels you’ll need for a 6.4 kW system depends on the power output (in watts) of the solar panels you use, which generally range in wattage from 250W to 400W:

Adding up the costs

The average cost of solar in the U.S. is $2.95 per watt, meaning our 6.4 kW system comes to $18,880 before incentives. A Tesla Powerwall battery costs between $14,600 and $16,850, so installing three Powerwalls would likely cost somewhere between $43,800 and $50,550 before incentives. Add that with the cost of your system, and you’re looking at a total installed cost somewhere between $62,000 and $70,000 before any rebates, tax credits, or other incentives.

However, remember that these are just the costs for a system capable of powering an average-sized (or slightly below average-sized) American home for a single, average day. In reality, not every day requires the same amount of electricity, nor is every day perfectly sunny. While the average daily usage in American households is 30 kWh, hot summer days with AC on full blast could use as much as 80 kWh.

Once you start considering seasonal and day-to-day weather variations, the prospect of going off-grid becomes more complicated. What happens if it rains for a week straight or if you live in a region with snowy winters? Just an hour of cloudy weather during the day could reduce the production of your solar array by up to 20 percent, meaning that if you only size your solar plus storage system to meet your average daily consumption perfectly, there may be many times throughout the year when your system doesn’t produce enough electricity to power your home. Going off-grid in nearly every case requires more than a day of backup electricity.

The only way to safely go “off the grid” is to ensure you’re ready for the most extreme situations possible because being left without power and without the electrical grid to pull from can be dangerous.