Off Grid Solar Power System Battery Bank Sizing! You MUST Do This!

How has your energy consumption changed since this video? In this example you consumed 30,570 W in 12 hours, or 2,547.5 W per hour, which is quite high, especially for overnight when household activity is usually lower. I'm guessing it was your electric hot water heater. I currently average about 18kWh per day, or about 750W per hour, in a much bigger house with 2 people in SE Michigan. My average always-on is currently 217W.

I am nearing retirement and will be returning to East Texas (I was born in Tyler) where I have rural property I am in the process of building a retirement home on and would like to be fully off-grid if I can swing it. FWIW, I am planning on a timber frame + SIPs for my house. My brother built a SIP home in East Texas back around 2005 or so. His SIP house was at 73F inside when power went out during that snowmaggedon craziness and he went to stay with our parents in Tyler to make sure they were OK. He returned 7 days later, still no power, no heat, and the inside of his SIP house had only cooled to 53F over that 7 day period of no heat. He does have some solar gain designed in which certainly helped a lot but this is essentially what I'm planning on except I like having a timber frame skeleton inside the SIP envelope.

Your videos are useful and informative. Good to see the progress you've made since you started.

You need insulation for hot water heater....then a timer. Even the grid i had a timer it was a hour a day for me so i could take a shower. It also had a bypass if hour wasnt enough. You really need one for an solar power solution.

Can you add a winder turbine to assist when sun is down?

once water is heated up it stays hot when turned off for at least 24 hrs. granted you can't take a shower like that but washing hands etc it will be hot . you can just heat it up when taking a shower, washing dishes, clothes if you wash with hot water.

Thank you for posting. We are currently configuring an off grid power system in Northern Nevada. I have saved this video for future reference. We will have a generator back up so we will have ability to charge when the sun is not producing power through the solar array(s).

Where in east Texas?
Im in east Texas

Thank you for a very informative overview 😊

I HIGHLY recommend in buying 2.5-3.5x more solar KWH then what your daily consumption is to Help maintain enough energy being put into your battery bank storage and into your home that even when cloudy theres still enough energy getting to your home use and keeping your batteries charged

Hi, very nice video. Couple of suggestions.
1. I like to monitor my usage using "SOLAR ASSISTANT". It runs on a Raspberry Pi and provides a timeline graphing of solar generation and loads. It's relatively easy to figure out what appliance is on at a particular time.
2. I think for most people 3 days of autonomous power yields a battery which is unaffordable. So perhaps you might define two or more modes depending on the weather forecast. Modes could be abundant solar, and no solar. If you know that tomorrow or the next day will fully charge your batteries you may want to keep all 3 mini-splits on. But if you know it will be overcast, switching to two or even one might be more appropriate.
Of course a generator may be the only source of power for those weeks when there is no solar.

Awesome explanation!!! I'm just lost on how to do this for my ice cream truck here in hawaii😮...I need 10000 watts surge power..but only 8000 watts running...and the most I need it for is 8 hours. I need help...I need help...I'm dumb...lol...Mahalo for all your info..love your channel!!

Great video no wasted time just pure analysis that’s what I like to see

So what do we add first? Panels or Battery, how should we step up?

Additionally, with laundry, use cold water and a clothesline. You live in a warm climate you really don't need a clothes dryer. Burning through 2000 kWh/month => ~60kWh/d that's 5 to 6 times what I use in my home. Do you have other commercial loads?

I think 72F at night is far too warm and wastes energy. Use an extra blanket. I live 300 km north of Toronto and I set my night thermostat at 14C. The home is well insulated and even at -10C the furnace often does not come on.
If you want figure out your HWH, then turn it off at the panel for a few nights when you are only running refrigerators and then turn it back on. You should get a decent estimate.
Your dog doesn't need a bed heater. It's an animal they'll figure it out.
Part of all of this is using less energy ... period, not just buying more batteries.

If power is non negotiable and you wana prep for improbable things? Id also get a 1kw diesel generator and store a few drums of diesel. It sucks but hydro carbons are very dependable.

Great explanation, thanks

I saw on the web site sizing chart that it mentioned several voltage amounts for the systems (12, 24, 36, & 48). what is the most efficient for longer battery use in a days time?

Dude I live in the Pacific Northwest your problem is simple you do not have enough solar panels if your charge controller can except 2500 W of panels do you need 5000 so you actually run at full power I have a 3000 W charge controller all in one hybrid I run 7500 W of solar panels

You don’t have enough solar panels if you cannot charge your system from 0 to 100% and five hours in full sun you do not have enough panels and you said you didn’t by stating you had to charger batteries From the grid you apparently have plenty of batteries just not a solar panels you have about 40% more battery than you need

We had a timer switch installed on our hot water heater. We have a family of three and we let it run for four hours every day. That gives us enough hot water for all to take showers and wash dishes. If we need more we can change it to be on longer or shorter.

There are different ways you can it. I have a separate box set up for each individual room. Easier to keep up with for me. The only thing constantly running is my refrigerator, my lights are so efficient that they could run all day and night, I don't need ac because the way I have it insulated it stays in the 70s even in the Florida summers.

How long does it take to charge all the batteries?

Discharged to 80%???

Two words... backup generator

so those batteries are basically 4x100ah @12v in series to make 48v .. and 5kw (as 100ah is 1.28kw)

Have you considered outing wind turbine to your system.. what's nice about wind turbines is they don't need sunlight to work so its 3 in the morning every storm that comes in and I started turning you're making power.. your way that you can add a water turbine to the system.. what was the other two ways that you can get power to your system without running a generator to charge everything.. probably the least expensive out of all those would be the wind turbines

a very nice video. but always in my mind how many kwh could win in winter in harsh conditions.For example i ve got a 10 kwh solar generator could it be generated at the worst situations in wintwer every mont at least 300 kwh that is our energy monhly needed.

Overall, this is a really good, down-to-earth video that's highly "relatable" (if that's really a word 🤠). The style of delivery is easy-going and friendly.

That said, I'd like to offer a couple of thoughts. There are opportunities to find the info in the video, but in the entire video, you never actually said you were running 48 volts. So, someone who didn't realize that and is using something OTHER than 48 volts is in for a surprise. They're not going to get 5KW per battery. I know you're not trying to hide it, but it would have been helpful to specifically call it out. (Don't assume they've seen your other videos and already know about your setup.)

You mentioned that you don't know how much power your water heater uses. With all of the options for inline meters available today, and given that most of the planet uses 240v, it seems like there should be options to put a meter on a load like that and get a daily average for consumption. It might be worth exploring.

Days of autonomy: You said you used about 62% of your battery supply for a 12-hour test. That's pretty much 5% per hour. So, if you set a discharge floor of 20%, that's about 16 hours. If you discharge all the way to 0%, you've got 20 hours. To get to 48 hours of autonomy with a floor of 20%, you need three times the battery bank you currently have. At $1650 each, 27 of the 48v, 100Ah EG4s will cost you $44,500 plus taxes and some serious shipping charges -- for enough power for just TWO days. And that's before you upgrade your solar array(s) to charge all of that. And that's for an 1800sf house. Then what happens on day three? You've got a dark house and a $44,500 paper weight in the garage. I don't say that to be critical, but to be real. If we're going to get autonomy, I believe we have to be willing to do two things:
- Reduce consumption. Don't run all three mini-splits. Share bedrooms. Heated dog bed -- seriously??? Look for alternatives to other loads. I think it's a mistake to think of an autonomous day as just another day, with no changes to how we use power. I know why people use a worst case like that for the purposes of estimating things, but I think that can cost people a truckload of money. When the grid is gone, habits based on the grid being available have to change. Lots of families can't just "keep buying batteries, keep buying panels". If increasing supply isn't practical, decreasing demand seems critical.
- Supplement sources. Heat with a fireplace. Use a generator to share some of the loads or to help recharge. Heat water with propane. Break out the grill and the Dutch oven. I live in one of the worst places in the country for solar, at a northern latitude that's famous for being cloudy and rainy. If you live where I do, being "solar elite" just doesn't work. No one here has solar of any consequence. If you're really "homesteading", is dependence on electricity for everything like cooking really the right choice?

Why do people always title their videos with stuff like "You MUST do this?" Can't they just be happy with "Here's what I did"? A camera and an opinion doesn't make one an authority that must be followed, right?

sadly Australia isn't up to this, sucks when things cost too much money.

I turn off the hot water heater during a blackout. We use electric kettles to get hot water as needed. This saves us about 10KWh per day.

So let’s say we use 16kw/h and have blackouts up to 12hrs so I would need around 400kw/h battery pack for that duration also could we charge the battery from the grid And have it on standby?

All seems good but seems like if you live in the Midwest cheaper to just buy electric for my 3/2 thought equipment was cheaper now guess not.

"Keep adding batteries. Keep adding panels" So, $15K worth of batteries can't run a house even a single day? F... it! Just connect to a grid and foreget all problems.

What’s the difference between solar batteries and solar generators?

100 Ah and over 5K wh per battery? What am I missing here? Battery voltage is not 12V?

I am thinking of running 300AH lifepo4 batteries, 4 in a series to 48v, do that 3 times then running those 3 together in parallel to give me a total of 900AH and 48v. Would you put it together that way or do you think setting the bank up for 24v and 1800Ah with the 12 300AH batteries would be better?

This helped me a lot saving my battery’s.. I put a propane tankless water heater in line whit the electric tank water heater.. the tankless got a battery on off switch, that I turn on in the winter months and off in February,, the cold water inlet of the boiler is than 45/ 50c that saves a lot of battery ( battery’s cost money to) another one is , if you are used to heatpump air to air ,, look at a diesel heater on allie 29,000, btu per liter ( they run fine on house oil ,, heatpumps below 5c are going to suck amps out of the battery for litle return,, kerosine in Holland is 45cents
🫲😑🫱 you can’t beat that

Excellent!

Only 72 degrees 😂

Hi I'm able to get my hands on almost 20 Volvo hybrid batteries but need to use a sol-ark inverter due to batteries max out around 63v. they are about 12k a piece . I have a 48v system now . my problem is solar panels .Do not have a lot of room ? if I have enough batteries is it a problem if i can charge them up all they way but have enough to run house. Jeff Does that make cence.

AC, heat, and water heater are the biggest hits to your daily energy use. I only have 11kwh of lifepo4 batteries. However it’s just for outages, we are on grid. We only need it for cooking and keeping freezers running.

If you install a propane tankless water heater on your electric water heater cold inlet , you will make it in the winter( 60c inlet ) whit your battery’s.. just turn the ignition switch of in the summer and let cold water run true it ..

Those battery calculators are confusing.


Each house uses average 3,500 but that’s not counting the extras I might use later

But I’m slowly stocking up the aptos dna bifacial 440 watt panels. I have 20 right now
Trying to figure out what’s the best lithium IRON BATTERIES
ARK or
Fortress or other
And what inverter etc to get
Sol ark or Schneider or other
And if I need some one to build it or how do I diy it .
I’m so confused

Thx a lot for all your efforts & congratulations on your set up. I only needed 2 batteries, but I decided to get 4 anyway. Because I got the best. The Discover AES 42-48-6650 gives me 6,650 amp per hour per battery. I will never run out of amp

I've been told lead acid batteries in the same bank need to have the same amount of discharges, same expiration dates, etc same everything. So I'm guessing thats not true for lithium? I'm not even sure how accurate that is.

that wiring though. this is why insurance companys are cancelling policies on homes with solar and or battery backup

I think the news said this pass winter was the most cloudy winter on record for Michigan & Ohio U right about going days on in with no solar I was to mad lol I ended up using my generator 4-5 diff times over the course of the whole winter & I'm in Toledo Ohio

first thanks for the info! I have searched and my question still remains unanswered , I totally understand the watt hours and consumption but what I am unsure of is how many (minimum) batteries I will need if I want to draw the full 13kw from my 6548 at one time such as a dryer surge etc…and not go into grid bypass. Will the BMS regulate the output current of each battery? If so how much? Thanks in advance..

lithium pleb, add water to your setup.