So how many solar panels do you actually need to to go off grid!? Well…here is the REAL answer. Asking how many solar panels you need to run your off grid home is like asking how many gallons of gas you need to travel in your car. Without giving any other information, there’s not enough information to answer the question accurately. The short answer is… It depends.
It depends on the total energy your electrical appliances and electronic devices use and how much you use them.
FIGURE OUT YOUR TOTAL WATTAGE NEEDED
Add up all the max Wattage used on every single device and appliance you will need to run. Then a good general rule of thumb is to triple that Wattage number. 3X the Wattage gives you a good number. Perhaps that’s a 3000 Watt system. Perhaps it’s only 1000 Watts. Either way it’s likely going to be between those two numbers. On average.
NOTE: This is a very general rule and NOT how you should really calculate things, but it will get you in the ballpark of where you need to be with the total wattage of the solar power system you’re building.
Your next issue is batteries.
How many batteries do you need to run your (AC, Fridge, Fan, etc.) all night?
This answer is a little more complicated than calculating a general total wattage you need.
“According to the United States Energy Information Administration, the average American household consumed 10,632-kilowatt hours (kWh) of electricity last year. The average kWh per month was 886, while the average kWh per day was 29”
Figure about 10k Watt-hours of annual usage. Divide that by 365 days, that’s a daily usage AVERAGE of 27.39 Watt-hours per day. Not too bad.
Then you have to convert Watt-Hours to Amp-hours (the measurement everyone uses for batteries) to figure out how many batteries you need.
Here’s an excerpt explaining how it works:
“How Long Will A 100Ah Battery Run An Appliance That Requires 400W? (Example 1)
A lot of people who own RVs or caravans are interested in how long will a 100Ah battery last if you run a 400W appliance with it.If you’re looking at 100Ah alone, it’s impossible to figure it out.
However, when you calculate the battery capacity of 100Ah and get 1,200Wh, you can quickly figure out how long the battery will last:
You have a 1,200Wh battery.
Appliance draws 400W.
You simply divide 1,200Wh by 400W and get 3 hours.In short, a 100Ah 12V battery will run a 400W appliance for 3 hours.”
SOURCE: https://learnmetrics.com/how-long-will-a-100ah-battery-last
If you’re running a small “beer fridge” that draws 400 Watts in an RV, tiny home, or off grid cabin, and your battery is 100ah, you can run it 3 hours, but you’ll drain your battery and that’s not healthy. So the calculations get a little more complicated because you have to factor in the safe discharge percentage of your batteries.
Assume you have a 10 200ah batteries in your battery bank. That’s about $5k worth of batteries and enough power to run that fridge for about 60 hours total. Again, you’re fully discharging the batteries when you do that and that kind of usage will shorten the life of your batteries.
Battery drain should be limited to around 50% or so but this number is subjective and relative to who is saying it and where the information comes from. I’ve seen the general 40/80 rule, which says you shouldn’t discharge less than 40% nor charge over 80% but in all my reading I haven’t seen much scientific data to support that rule.
50% is a good happy medium in between all the “expert advice” out there that’ll tell you 80% or 40% or 60% or whatever other number they pull out of the air. Yeah I pulled that 50% number out of the air, but I have no incentive to give you any bad information, and I’m not selling you anything. I’m giving you information based on what I look for if I’m building a solar power system with a battery backup energy storage system.
NOTE: Keep in mind that a lot of those “EXPERTS” out there also have an agenda and a monetary incentive to tell you these numbers to UPSELL you if they work for a solar panel installation company. They’re going to try to upsell you on the batteries and solar panels knowing full well you don’t want to do all the calculations necessary to figure out how much power you actually need. Not saying you’re lazy or not smart enough to figure it out, but it’s a lot of technical jargon and people are busy and don’t feel like dealing with it. Just be aware that when you ask an “EXPERT” ask yourself if they have a monetary incentive to tell you the number they’re telling you.
So…How Many Solar Panels Do You Need To Run Your Off Grid Homestead?
As many as it takes to run all your electronic devices and electrical appliances. That’s how many.
Do the math. Or hire an “expert”. That’s your choice.
The IF Game Is Infinite
If you’re needing to know a good average, then A 1500 Watt solar panel system with 3 200ah batteries should be sufficient. That should give you a good amount of energy to run your fridge and stove and microwave and charge small electronic devices like your laptop, smartphone, and tablet.
If you need more power, double that number to a 3000 Watt system with 6 200ah batteries.
If it were me and I were running a full house with all the bells and whistles and a 2500 square foot home, I’d build a 220 Volt, 3-phase, 10,000 Watt solar panel system with a 20 200ah battery backup system with 2 10k Watt sine wave inverter/charge controllers, meters, and breaker box.
Ok Enough Of This IF game
But for your RV or camper trailer, tiny house, or off grid cabin in the wilderness, all you will probably need is a 1500-3000 Watt system with 3 to 5 good quality 200ah deep cycle batteries, a good quality 5kw inverter/charge controller, charge/power meter and breaker box. Be sure to have a qualified electrician install it for you. It’s worth the peace of mind to have it installed properly.
How Much Will My Solar Power System It Cost?
About $2500 to $5k on average. Prices of solar power systems with battery backup energy storage systems have come way down to less than $1/Watt installed.
NOTE: A solar panel system is NOT COMPLETE without the batteries because you need to run your equipment 24/7/365 on cloudy and stormy days and at night when the sun isn’t shining. To supplement your charging ability add a 500 to 1000 Watt portable or permanent wind turbine to your system. When it’s cloudy and stormy the wind usually is blowing so you’ll always be charging your batteries.
Shop around. You have the power.
Solar power is the way to go.
