Got a rancher neighbor down the road that was totally unprepared for the recent ice storm. Even after having suffered through the Big Chill a while back, he was not ready for this one. They say they are going to get solar and batteries for future problems like this. I have no idea if that’s a good idea or not. My instincts would be to think that it wouldn’t be worthwhile for a long outage (4 or 5 days), but I really don’t know. A few of you guys are very knowledgeable on this, so I ask you whether or not their plan is worthwhile, and what sort of cost they might be looking at?

How much solar is needed? How big or how many batteries would be needed? Can resistance Heating be run with this approach?

The questions aren’t for their benefit, but are for mine. This is something I probably need to be a bit more informed on.

Be better off with a generator…

We have solar but still plan to add a generator for longer outages. Having solar I won’t need as large of a generator than I originally planned on.

You have to figure out your usage (going to be different for everyone) then how many panels/batteries to supply that usage. I wouldn't think it would be a good idea or option to rely 100% on solar during an outage because what happens when there is no sun...like this week it rained a ton a buddy of mine with solar told me he knew it was nasty here because his solar system had only produced 1Kwh...on a normal sunny day he produces 30Kwh. He uses it more to supplement his power usage. At the time he was in AZ but could monitor his system and knew it was not sunny here...I thought it was interesting the difference in what a sunny vs rainy day could produce with his smaller system.

Not sure I helped at all but good luck.

Electric heat is a resource killer. 100% efficient, but uses a ton of power. He'd have to way, way upscale his battery capacity to run for that long, since an extended outage like that most often comes with cloudy weather. Even if his house is all electric now, he'd be well ahead plumbing a stub out for an emergency propane heater and putting in a separate tank if he doesn't have one already. Then just use the solar to keep a couple lights on, the fridge cold, and occasionally run the HVAC on fan only to circulate the warm air through the house.

Sounds like someone offered him the Kool-aid and he drank it.
Unless he has a garage stacked full of batteries and then the inverters to convert to AC power and then probably 1/2 acre of solar panels he would be better off having a propane powered genset with a automatic transfer switch. JMO.

Our average electric bill for a 2700 sq ft home and 1400 sq ft shop is about $200.

For $212 a month over 20 years or about $40k if paid up front I could power my house with solar. For an additional $10k I could be off grid with a Tesla Powewall. All panels would be installed on my shop roof.

If you look at rising energy costs and if you feel you’ll be in your home for the next 20 years it’s probably worth it.

Do the math on the storage capacity of a Powerwall module. It's around 13.5 kWH which is the same as running a little 4500 watt portable generator for three hours - then it's dead until you charge it up again. Making your own power and having adequate battery storage to bridge cloudy days does not make economic sense until you are paying 45-50 cents per kWH for grid power.

Not worth it. Whole house generator is the way to go.

I did the calculation on my old ac unit 10+ years ago so I can’t recall all the numbers. But to run the ac at night on batteries, I needed 5-8 fancy 6v batteries and it depends on how fast you want to recharge them the amps of the solar panels. I think I did that on 6hr run time. The batteries are expensive. Theyre specifically used for solar backup and the cheapest one I found for me was $680. That number I remember cause I was shocked. They range from $400-10k and size of 15 gal gas tank.

To add. To get max amp from solar panel, it needs to be facing straight on to the sun as long as possible. My setup is to just maintain the batteries on my bronco, atv and boat. The solar panel has slight angle because the way it’s mounted. Summer time I get direct sunlight from 11am-1pm ish. My panel is 100 watt 4amp and have charge controller to regulate. When sun is directly over, Max amp I’ve recorded is 1.8-2.7 amps. On cloudy days, i get between .1-.8 amps.

Like pdr55 stated, You need a lot of batteries and a lot of panels. I wanted to run my ac during summer time but gave up because of the price tag. Gas generator needs maintenance but cost way less.

Eugene

Yep. A typical battery bank sized to handle some air conditioning for residential solar systems costs $15,000 to $30,000.
The most cost effective off grid system is a blend of solar, batteries, and generator.

Based on the average home consuming 28 kWh/day, one Powerwall will be able to power a home for 12 hours. Two Powerwall's will power a home for 18 hours, and three Powerwall's will run a home for 24 hours.

That’s without charging. Yes, you’d probably run out with cloudy days but I running a generator for days is extremely expensive.

Ideally I’d like to stay on grid but switch off if needed.

During this most recent ice event, we were out of power for 4 days (5 if you ask my wife). At first, with the generator, we ran the whole house as we normally would. Propane demand was significant, but then the generator balked at running everything plus the heat pump. Then we switched the heat pump off, stoked the fireplace like it was a Mississippi River steamboat, and brought in a couple of Buddy Heaters. The Big Buddy, with fan, kept the core of the house perfectly warm, and a small one in the bathroom kept the wife happy. When we ran like that, the generator rarely got off idle and propane demand at the generator was much less. We agreed that next time we’ll run like that. It was comfortable.

But…if the temp went down to 10 degrees or less, and stayed there for a week, and we were iced over to the degree that I couldn’t get propane cans filled, we’ll likely be in trouble with frozen and shattered pipes. So, get more propane cans….and I did.

Well, 28kWh per day x 30 days = 840 kWh per month - so a power bill of $100. per month or so.
With a $200 power bill, your consumption is 2-3 times that, so you will need quite a stack of Powerwall to bridge a few days.

I do agree with what you would like to do and all of us would love to be grid independent! Most often, a scaled-down system with a blend of solar, batteries, and generator is the best compromise. It's kind of like how I run during power outages: I use a 5,000 watt portable to keep all of the basics up and running, but I'm sure not going to run the big appliances at the same time.

I am in the solar battery business and I help to design large residential battery banks every week. I see incredible amounts of money being spent to achieve total energy independence.

Marc

Since we are talking about this:

One of my favorite design approaches for power outages and "no sun" conditions on solar systems is to use a smaller generator running into a battery bank.
For an extreme example, using the smallest possible super quiet little Honda 2200 generator:
It produces only 1800 watts per hour using around .30 gallons per hour.
BUT 1800 watts x 24 hours = 43kWh per day burning about 7.5 gallons of gas per 24 hours.

All of the generator output feeds a battery charger supplying a battery bank. An inverter converts battery power to 120v (or 240V).
The battery bank handles the loads including the peaks and starting surges. It's conceptually just having a garden hose running 24/7 into a water tank. The water level in the tank goes up and down with usage, but as long as the input is enough - the water tank (batteries) never goes empty.

The battery charger, batteries, and inverter are not 100% efficient, so you get a net amount of more like 30kWh per day in usable power in this example. Upsize the generator even a little and the numbers change again. This is how most off-grid homes run efficiently.

Add some power production from solar, and your system has some real horsepower. This is what I mean by using a blend of solar, battery, and generator.

I like this approach!

Been though 20+ years of relying on solar power and batteries to power computer and communication's equipment metering millions of dollars of natural gas every day.

Winter weather = long periods of overcast, snow\ice covering your panels, and a 50% decrease in battery capacity due to temps.

Panels make a little when its heavily overcast, but its about 15% - 20%. You need to use those numbers in the calcs and plan on a at least 7 days of no full sun.


Even at 7 days, we have had 4 instances in the last 6 years where 7 days was not enough.


Get a generator and a backup generator.

Marc on track here...with one qualification. What type of batteries and where will they live? Unless the batteries are in an area that will be heated during the power outage, you loose a LOT of battery capacity as temp falls.


Forget Lithium batteries if they will live in the cold. While they provide more discharge power when cold, they must be warm when you recharge them. You'd need to warm the up before charging. Do some Googling and you will find some great info on this about Teslas

But it is still a LOT more money than buying a bigger generator!

I have a wide variety of customer types:
Some chose to go "grid tied - battery backed" small solar boost. These are often in remote locations where getting more fuel ain't gonna happen under certain conditions so absolute minimum fuel consumption is most important.
Others who are not so remote, want batteries so their generator runs for very limited hours.
Some go to great lengths to totally silence their generators to a stealth level which you can do with a tiny generator.

Then there are the three letter agency applications that can get exotic!

NAK, Yes, sir that is a good call!

The temporary capacity loss at low temperatures is always accounted for in the design. (You have about 50% capacity while the core of the battery is at 20F) I apply a specific breed of AGM batteries in a huge variety of applications including banks for buoys in the Arctic Ocean and steel boxes in the desert sun along the southern border. It's what I do for a living.

The Ecoflow solar generator looks interesting.

I have learned a ton of good info from this discussion. It really is amazing about the depth of knowledge and information on so many topics here on the forum.

I just can’t see spending all the money for a room of batteries that have a life expectancy plus the cost of the panels for something that might be used twice a year. I don’t care what the price of propane is. It’s virtually nothing compared to a solar/battery system.

Lots of good info here. I will continue using a generator tied into my electrical panel. It can run everything but the AC and I have a couple portable units if that occurs.

This ^^^^^^^ is the exact approach we’re taking…..grid free nights to recharge batteries…..solar, then batteries, then grid during the day….generator as a backup when the grid is down.

I’m not interested in getting “off the grid”….just building us a buffer. Same with drilling the water well, getting bees, setting up a garden and orchard/vineyard….and looking into chickens and or quail…..

Self reliance used to be the norm….we’re trying to make it more our norm

I wish it was a couple of times per year! It's mid-February and we have been down three separate times already. 22 hours, then 19 hours then 39 hours. My Honda's get some good exercise!