How did your solar fare during the January '24 freeze?

[EastTexCowboy]

Just curious how everyone's solar and/or batteries did/is doing during this last freeze. I'll start. Mine didn't.

Let me preface this by pointing out I am heating and cooling about 4,000 sf and of that about 3000 sf has 10 ft ceilings. So, if you compare to typical 8 ft ceilings and go by cubic feet it's closer to 5000. That's a lot to cover with the size system I have. (System size in my signature.)

Last Saturday night it only got down to around 35 degrees but when I got up my batteries were down to 16%. With predicted temps in the mid-teens and little sun I realized this is not going to work. So rather than fight with it I just switched everything back to grid. My thinking was run it all on grid with the whole house gen as primary backup. Then get my batteries back to 100% and let them sit there as secondary backup. This turned out to be a good decision.

The two worst days here were Monday and Tuesday. I used 160 kwh and 180 kwh respectively. Any solar contributions would have been a drop in the bucket. Now, I know I'll get some of the typical responses about such massive usage but reference the square footage I'm heating above. It just takes a lot of BTUs, even with a very efficient home and heat pumps. From my perspective it wasn't bad. Last year during the Jan '23 freeze and similar conditions my usage was 230 kwh on the worst day and I wasn't heating the garage then, which is another 440 sq ft or thereabouts. The Mitsubishis get all the credit on that reduction - I'll circle back to that.

This was my first winter freeze since switching most of the house over to solar so it was definitely a learning experience. What did I learn? Not really anything I wasn't expecting but perhaps still a wakeup call. If I ever truly wanted to be close to off grid I'd need to add more panels and a LOT more batteries. My little 60 kwh bank doesn't even come close. While I could certainly lower the thermostat and do some other stuff to cut my usage quite a bit, I don't see any way to get down to a level that would allow the current system to cover my needs. I was already planning on bumping the batteries up to 120 kwh. Now I'm leaning towards mimicking @timselectric's plan and going closer to 200 kwh. I wouldn't even consider this if it weren't for the ongoing drop in battery prices. I'm starting to think it's doable. It likely still wouldn't carry me through a cold spell like this one, but it would get a lot closer.

The other part of the equation is production. Let's face it - when it's cloudy all day for days adding a bunch more panels may not have much of an impact and there's certainly an issue of diminishing returns on that investment. I do need to add more, if only to cover the summer needs. I was close to covering the needs in the summer, even when it was over 110 F. So I'm still thinking adding another 7k or so of panel production would be a good move. The negative is the only place I would be willing to add them is the north facing roof of the shop. Even though there is little slope on the roof, in the winter those panels are going to be anemic in production.

Back to the heat pumps. I was once again impressed with the Mitsubishi. Not only because the consumption was less but they kept the house toasty throughout the freezing temps. Last year we had some 10 year old Luxaire units that ran 24/7 and still the bedrooms wouldn't hold above about 62 degrees. This year the house stayed around 72 degrees and the garage was at 70 with very little in the way of problems. I did see a drop Wednesday morning when it was still 16 degrees on one of the units for about 3 hours. I talked to my HVAC buddy who installed them and we decided it was likely in a heavy defrost cycle. That seems likely since it eventually recovered, but it was warming up outside at the same time so I'm not 100% sure on that. Even during this the inside temp only dropped about 4 degrees in the bedrooms serviced by this unit. I'm gonna call it a huge win on upgrading to the high efficiency heat pumps.

Other than that, we didn't have many issues. I had a hot water line freeze up but I managed to get it thawed and re-wrapped then let the water drip. Also had a line freeze that supplies water to one of the pastures but it didn't burst so I got that thawed and did a little work on insulation so hopefully it's good. I still haven't switched back to solar since it's supposed to be cloudy and back down in the 20s at night Friday and Saturday nights. If it's okay with y'all, I'm done with freezing temps for this winter. Spring can come along anytime now and I'll be happy!

One other note on my batteries. I've had a problem with two of them not getting back to 100% for months now. Something like 87-88% and only three lights on the panel. With them sitting idle and soaking for a few days they are all back to four lights. I need to hook up my laptop and see what the actual level of charge is, but the float charge seems to have helped them.

I feel like DIY solar is still a little bit of the wild west and we're all learning as we go. I can't help but think the time, effort and money we're all putting into it now will only help us and others going forward.

So how did you do during the freeze? Any good stories? Any suggestions or comments?

Stay safe and stay warm out there.

 

[Q-Dog]

Our house has electric heat and we lost grid power for a few hours. We were able to keep comfortable with a couple of room heaters running off of our backup battery. We used about 45% of our battery capacity to stay comfortable.

I didn't originally build the system to run heat, but we did just fine. It will only get better for us as we install more solar panels.

 

[Hogheavenfarm]

I also swapped back to grid in anticipation of power outages, luckily we had none but a few blips. Back on solar since yesterday. I have no heat ability hooked to solar, so LR was 54 degrees yesterday morning, a bit better today at 57 degrees, but colder temps are expected over the next few days. I am using a woodstove and it is running b#^*@s out but the house is 2000 sf and we have a north wind blowing. When the temps get down to less than 20F, woodstove just cannot keep up. Warmer weather coming next week though.

 

[green mountain boys]

Try lowering your thermostat from 72 to 68 or even lower. You will see a huge decrease in energy consumption when the outside air temperature is cold.

 

[EastTexCowboy]

Try lowering your thermostat from 72 to 68 or even lower. You will see a huge decrease in energy consumption when the outside air temperature is cold.

We talked about doing that but I really wanted to see if the heat pumps could keep up, and they did. If there had been a power outage we would have almost certainly done so, although the gen is capable of carrying the load easily. I agree that it makes a major difference to lower it by only a few degrees. The other thing is the boss likes to be comfortable and frankly, so do I. If I have the option and ability to keep it at 72 it's hard to drop it to 68 just to save a few dollars. But everyone has priorities and those priorities can certainly change with circumstances.

 

[Hogheavenfarm]

Haha - no thermostat, just the heat dial on the woodstove hovering at 500 degrees. Furnace thermostat is set to 50, as low as it goes. Even at that, its still kicks on once in a while. At this rate we use 60 gallons of fuel oil per year, I refill it with diesel I buy in September, 5 gallons at a time.

 

[Mattb4]

Yeah my wood stove also could not keep up and had to turn on the electric heat from the grid to supplement. Going to see a major spike on my electrical bill for this January. My thoughts on going completely off grid are being revised a bit.

 

[Q-Dog]

I've been telling my wife for some time that we need some sort of supplemental heat here, and after yesterday's grid outage she finally understood why. We have a gas cooktop and clothes dryer, so adding a gas heater shouldn't be a big deal.

But now there are other options. We have a pallet of solar panels to install, and a low temp mini split would probably work for us.

 

[EastTexCowboy]

For me, the most important lesson was this. Without a separate heating source, and if you're in a climate where temps drop below freezing for multiple days, you are not going to be able to sustain the same level of comfort with solar alone. I mean you can, but the cost of panels and batteries and the associated support for those is going to be hard to justify for simply covering needs for a few days a year. If you're in a cold climate you probably already have a different heat source. If you're in a more temperate climate you may want to consider one. This should be especially important to newbies, reinforcing that you should be realistic in expectations and plan accordingly. Even with lowered thermostats and other reductions in use you may run out of battery fairly quickly. Of course, there are many factors and my example is likely not typical so there's that. Heating a 1200 sq ft home with good insulation, high effieciency heat pumps, and proper management would be much more doable.

 

[Troubleshooter]

Temps here got down to -22 on Saturday. Not much sun, so I ran generator quite a bit. Ran two 250W heating lamps, for chickens and well pump manifold, so that doubled my average running consumption, which chewed up through my battery pretty good overnight.
Wood stove kept our house above 70 degrees, my supplemental heat is a propane furnace, but I never needed it.
I have ~12000W of panels (half on the roof of the shop, which is still covered with snow, the other half on the ground array), my lesson is I need another ground array to keep some power coming in even when overcast.

 

[millsan1]

We got down to high single digits, a few days of low teens. Everything running as expected, nothing really of note.

We heat with a wood boiler. One of the best decisions I've made.

 

[EastTexCowboy]

We got down to high single digits, a few days of low teens. Everything running as expected, nothing really of note.

We heat with a wood boiler. One of the best decisions I've made.

We looked at adding a fireplace but it's just not practical on this house. I envy you for that! I keep kicking around adding a couple of NG wall heaters or something. It's hard to justify either considering how few days we have when it's really cold.

 

[PreppenWolf]

We heat with wood. It doesn't require electricity and we can keep the house at any temp we want all winter.

Want the house 78F while it's 10F outside? No problem, open the vent another turn. We keep the house at about 72F and it only takes 3-5 cords of wood for our NH winter, which costs about $750-$1500 to heat the house for the whole year. House is two story 2000sqft plus a full basement.

There is no way I would use electricity to heat the house and heat pumps don't work at our cold winter temps. I've seen -36F in the last ten years and every Feb is below 0F for many nights.

The snow is great though. It increases our daily production by more than 70%

 

[wdwtx2.0]

We looked at adding a fireplace but it's just not practical on this house. I envy you for that! I keep kicking around adding a couple of NG wall heaters or something. It's hard to justify either considering how few days we have when it's really cold.

A good wood stove would work wonders for cutting your electric consumption.
If you have a good supply of trees, it is a relatively cheap way to supplement heat.
The electric units only come on when the fire gets low.
Plus, who doesn't like watching a fire burn.

 

[Cmy]

Not 4,000 sq ft but 2,700 with a 700 sq ft addition added in 2019 for mother in law. Addition was done right with sprayed foam insulation, two Mitsubishi GL-09 minisplits, and a propane tank less HWH.

She does like the mid 70s and the minisplits had trouble keeping up. Added a small electric room heater but then she found the 'emergency' switch for the minis which set 75F for temp and sucked up the KWs to achieve it.

Still planning solar and noted the light snow coated the planned solar area for a day and a half. Max day's total kW was 84 vs pre front 30-40 kW. Wondering if a generator is better back up than batteries? Local utility solar inspector came by to help with planning. He uses a generator as backup, with its own 500g propane tank, because he thought batteries would be more for his wife to manage while was out working on lines.

 

[SparkyJJO]

A good wood stove would work wonders for cutting your electric consumption.
If you have a good supply of trees, it is a relatively cheap way to supplement heat.
The electric units only come on when the fire gets low.
Plus, who doesn't like watching a fire burn.

It is. My old house had a wood burner when I moved into it years ago. I just hated messing with the wood, and the mess it made, and I didn't even have to chop it because I already had a bunch left over from the previous owner.

In my case in Ohio I just installed a new high efficiency heat pump furnace with propane. It was cheaper to keep the house at 70 with that than to keep the thermostat at 60 and burn the wood when I was home with the old fuel oil furnace, go figure. I stopped using wood after that.

Current house has a measly 80% efficient nat gas furnace with poor ducting to the master bedroom so we have a plug-in heater to keep that room warmer. It does ok otherwise, and because nat gas is cheap it doesn't do horrible. Not bad enough to warrant the up-front cost of replacing with better. I may redo the ducting though to improve things.

 

[timselectric]

It was dammed cold. But everything went as expected. With the higher risk of grid failure. I raised the minimum SOC to 70%.
I did have one pipe freeze. But, it didn't burst. And was easily thawed, once noticed.
My biggest complaint was that I spent the last few days working on the river. (Brutal)

 

[DIYrich]

This was my first winter freeze since switching most of the house over to solar so it was definitely a learning experience. What did I learn? Not really anything I wasn't expecting but perhaps still a wakeup call. If I ever truly wanted to be close to off grid I'd need to add more panels and a LOT more batteries. My little 60 kwh bank doesn't even come close. While I could certainly lower the thermostat and do some other stuff to cut my usage quite a bit, I don't see any way to get down to a level that would allow the current system to cover my needs. I was already planning on bumping the batteries up to 120 kwh. Now I'm leaning towards mimicking @timselectric's plan and going closer to 200 kwh. I wouldn't even consider this if it weren't for the ongoing drop in battery prices. I'm starting to think it's doable. It likely still wouldn't carry me through a cold spell like this one, but it would get a lot closer.

With that much "want" (72 degrees), I would see what the "need" would be to keep the house at 60. What is your "critical needs". If 300kWh to keep the house at 50-60 degrees for 3 days with minimal sun and 10 degrees outside will save the house, I would shoot for that minimum. Turn off the water, close up the house, and drive north for a vacation for a few days when the cold comes.

 

[EastTexCowboy]

A good wood stove would work wonders for cutting your electric consumption.
If you have a good supply of trees, it is a relatively cheap way to supplement heat.
The electric units only come on when the fire gets low.
Plus, who doesn't like watching a fire burn.

We looked at those too, and decided against it. At least for now. There's no good place to install one with the layout of the house. It grieves me a little because we have 45 acres or so of mostly red oak.

 

[EastTexCowboy]

With that much "want" (72 degrees), I would see what the "need" would be to keep the house at 60. What is your "critical needs". If 300kWh to keep the house at 50-60 degrees for 3 days with minimal sun and 10 degrees outside will save the house, I would shoot for that minimum. Turn off the water, close up the house, and drive north for a vacation for a few days when the cold comes.

Not a bad idea. It's hard to leave when it's that cold because we have cattle and they require some attention when it's cold. Mostly water related issues like breaking ice in the troughs and ponds.

We could certainly survive with the house at 60 even staying here, and would do so in a jam. That's actually part of our emergency plan. But so far it isn't an emergency so we just use the POCO and keep things comfortable. It's a choice on our part rather than a necessity. If I do take a vacation in January I'm heading south, not north! ?