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How much solar power do you need to go off grid? Making the leap to off-grid living can be daunting, and calculating your energy needs can be confusing. Take a look at what you need to consider before making the move to off grid solar.
If you’re considering going off the grid with solar power, there are a lot of important questions you need to ask yourself before choosing a system.
But if you’re looking for a cut-and-dry “you need X watts of power for your off grid home” type of answer, then you need to keep reading. Every home is different and your needs will definitely vary.
In our old home on the grid, we used upwards of 900 kWh per month. In our new off-grid home? We’ve reduced our power needs enough to get by with the following:
6 solar panels producing roughly 1100 watts, 4 batteries equaling 500 amp hours at 24 volts, and a 4000 watt MagnaSine inverter
How? Keep reading to find out how we figured out our needs and designed a system to match.
First, if you’re unsure of how off-grid solar works check out this comprehensive beginner’s guide to going solar here.
Estimating Your Solar Needs: Start With Where You Are
Every household’s energy needs will vary widely. If you’re currently living in a normal, grid-connected home, chances are pretty good you don’t consider how much energy each appliance uses and how often you use it.
Before we built our off-grid house, we lived in a normal little mid-century ranch. We used electric for everything except the stove,furnace, and water heater, which were powered by natural gas. Our normal kWh usage per month ranged from 750-1000 kWh per month as stated on our bills.
If we were going to try to provide that same level of power to our house now, we’d need at least 6250 watts of solar panels (or more)! And that doesn’t even take into account the amount of batteries we’d need, not to mention the cost of mounting hardware, conduit, wiring, battery housing, and so on. A system this size could easily cost in the $20-30K dollar range. This might be okay if you have lots of money to throw at such a large project, but if you’re like us you’re on a budget.
How To Figure Out How Much Solar Power You Need To Live Off Grid
1. Look at your current energy consumption.
Look at your power bills for the previous year. How much power do you use month by month? How do your needs change through the seasons? What kind of climate do you live in?
Our old house ranged anywhere from 650-1150 kWh each month depending on the season. We managed to reduce our energy needs so that we can easily rely on a 1.1 kWh solar system by following these next guidelines.
2. What uses the most electricity?
If you live a normal “on grid” lifestyle, the majority of your electrical usage can probably be traced back to:
- air conditioner
- electric furnace
- water heater
- clothes dryer
The good news is that ALL of these big items can be reduced, replaced with a different fuel source, or even eliminated altogether. Take stock of the energy hogs in your home.
3. What electrical loads can you shift or remove?
Your refrigerator, water heater, clothes dryer, and stove can ALL run on propane if you so choose. There are also some pretty cool low-power ways to replace or reduce your needs for these big items, like line-drying clothes, hand-washing dishes, creating a solar water heater, building a root cellar, and so on.
Instead of a traditional forced-air furnace, consider a wood stove or radiant heat.
And air conditioning? Try going without it! I realize that my southern readers are probably not happy with this thought, but hear me out (we’re in Kentucky, so while we don’t get the crazy heat you might have in Mississippi, it still gets pretty darn hot).
We can go without AC because our cordwood house’s design keeps it cooler naturally.
Our cordwood home uses its thermal mass to keep the temperature stable day and night. We also utilized some passive solar principles to make the sun work for us, keeping the house cooler during the summer and warmer during the winter.
Note: AC is certainly a safety concern for some people in different health statuses, climates, and building scenarios, but you CAN size your system for this. Just understand that you may want to either size a dramatically larger system or opt for a grid-tied solar system instead. You may also explore natural cooling options such as earth bermed home designs.
4. What smaller electrical loads do you have?
Smaller electrical loads add up as well. I’m talking things like computers, phones, wireless routers, small kitchen appliances, lights, etc.
Leave your TV or other electronics plugged in all day? Use a power strip and then turn it off or unplug it when not in use to eliminate phantom loads.
Think you need a microwave and toaster? You totally don’t! Sure, you could get a smaller microwave for your off-grid kitchen, but I’m willing to bet that if you’re like us the microwave makes it easier to make poor food choices.
There are tons of ways to save power around the house if you just look! Practice saving energy BEFORE you make the leap.
5. Assess your usage with a Kill-a-Watt
The Kill-a-Watt is a pretty cool, inexpensive way to see what your appliances are REALLY using. I’ve plugged in everything from my flat iron and computer to our front-load washer and television.
One of our goals was to really understand what everyday items really use, and not just rely on estimates. Some of my findings were really surprising!
For example, I thought that our 14-year-old front-load washer might use 1000 watts to run a cold wash, but when I plugged it in I found its peak wattage was only 110 watts or so, with most parts of the cycle using 40 watts or less and the entire cycle taking only .1 kWh to run! I would never have known if I hadn’t tried it out.
6. Can you design your house for efficiency?
If you’re building a home from scratch like we did, you have a golden opportunity to design an energy efficient home.
Use passive solar design principles like:
- orient your home to the south (if you’re in the northern hemisphere)
- place most windows on the southern face of the house, fewer on the east and west, and few to none on the north
- insulate and seal your home as much as you can afford
- use thermal mass (ex: our cordwood walls, insulated concrete slab) to regulate temperature
Once you’ve assessed your power needs, you’ll need to design a system to provide your power. But how do you start designing a system?
Getting Help With Your Solar System Design
Once we determined what electrical loads our off-grid house would have, we started looking for the most cost-effective way to get our solar components. Even though we had experience with wiring a house and had a pretty decent idea of what off-grid solar components do, we didn’t know exactly how to put together a system that would meet our needs AND meet code.
Reasons to talk to solar professionals
There are many nation solar wholesalers and smaller local companies who are highly knowledgable about all of the solar components, installation procedures, and subtle details that go into designing a system from scratch. They are also committed to helping do-it-yourselfers like us do the best job possible without breaking the bank.
We ultimately chose a wholesaler called Mr. Solar, for several reasons. Their prices seemed the most reasonable of any companies we checked, and they were able to work with us to design as a system that could meet our needs.
We worked with our rep for over a year before we made our purchase. He was patient with us, occasionally giving us price updates and advice whenever we asked. He’s also been able to give us great assistance in figuring everything out as we’ve been installing everything and cooperating with our local electrical inspector. Whenever we’ve had changes to make, he’s been super helpful!
Save time and money by talking to solar providers directly
Do your research to find companies that best suit your needs. If you’re comfortable with installing electrical components, definitely give wholesale companies a try. They will design a system and ship you the components to install yourself. If you need more guidance or don’t trust your skills, look for knowledgeable companies and private installers in your area.
And of course, we could have gone out and purchased all of our components separately, but we would have spent more money overall and we wouldn’t have gotten the personalized help we’ve received so far.
If you’re going to DIY a solar power system, talk to real people in the business and get honest, personalized advice before you make such a large purchase.
Thinking of building your own homestead? Grab our free quick-start guide here:
Check out our homestead progress and find out more about our cordwood homestead project here. You should also join us on Facebook, Twitter, and Instagram. I’m always pinning lots of great ideas on Pinterest too! Thanks for reading!