We just had a major (for us) storm with electricity outages lasting from 4 hours to days, depending on where you lived and how bad the power lines were hit in your area. We lost power in our house for 12 hours, which is the longest power outage we have had here in the ~36 years we have lived here. The first thing we wanted to use was a fan! So, I am fresh off the topic of emergency power needs for comfort fans issue.
Granted, your two 200 watt panels charging up two 12.8V 100Ah LiFePO4 batteries is probably a better setup than mine. I was using my Ryboi 18v batteries with an inverter, providing up to 300 watts of power. But I have a large collection of those tool batteries, so maybe something like ~45 batteries averaging 4Ah each for about 180Ah total. Your system is much better for a longer power outage, without having to swap out batteries like I did.
Here is what I learned about using fans on battery power.
1) Power inverter type matters: My first idea was to use a 4Ah tool battery in my inverter and run my electric box fan. What I found out is that the electric fans did run, but the modified sine wave power of the inverter caused the fan to whine in disapproval. I was not expecting that.
2) Get a high efficiency fan: OK, besides the whining of the fan on my modified sine wave inverter, I quickly discovered that my inexpensive box fans - that I have had for years - also required many watts to run. My inverter has a built-in power output usage meter, and I could see that my 4Ah battery would only power the electric box fan for just an hour. I tried a few different electric fans, all of the same type, and they all used more watts to run than I was expecting. All of them would run about an hour on my inverter with a standard 4Ah battery.
Instead of using the inverter to power my electric fans, I ended up going out to the garage and got my 18v fan which was made specifically for the 18v batteries. That turned out to be a much better solution. I have a newer 18v Ryobi fan and here are the specs on that unit...
**Ryobi 18V ONE+ Hybrid 7.5" Whisper Series fan**:
- **Low speed:** Up to **18 hours**
- **Medium speed:** Around **10–12 hours**
- **High speed:** Typically **6–8 hours**
These numbers are based on a fully charged 4Ah battery and average usage. If you're using a different Ryobi fan model or pairing it with a larger battery (like 6Ah or 9Ah), you’ll see longer runtimes. And since it’s a hybrid fan, you can also plug it in with an extension cord for unlimited runtime when near power.
For our situation, low speed on my Ryobi fan was good enough to circulate the air that we wanted. But it's nice to know that I could have run it on full high speed for 6-8 hours before needing to swap out the 4Ah battery.
Another big plus was that the 18v Ryobi fan was indeed Whisper Quiet especially compared to the whining electric fans running on my modified sine wave inverter.
Lesson learned for me is that the type of fan and its efficiency matters a whole lot!
3) Test your emergency equipment before the power outage. Although I had tested my 18v power inverter on a number of devices, I had never specifically used it on my electric box fans. I was surprised on how inefficient my electrical fans were and that they had an annoying whine when running on the inverter.
If your inverter does not have a built-in watts meter to see how much power output you are using, get something like a Kill-A-Watt meter and record your devices' usage. That will let you know how long it should run on your battery banks.
I think the idea of using a small electrical heater in the winter will use a lot of power. My electric heaters have a 1,500 and 750 watt settings. At the lower heat setting, you would only get about 3.5 hours of use before draining your solar battery bank overnight.
200Ah X 12.8 volts = 2560 watts
2560 watts / 750 watts per hour = ~3.4 hours of run time.
Is that long enough for you? If not, I would suggest looking into those small propane tank heaters that are made for indoor use and maybe buy a carbon monoxide alarm for extra safety. They heat up faster and run a lot longer than an electric heater.
Personally, I would save the electric battery bank for lights, radio, TV, etc.. and hope the power gets restored soon.
We seldom get power outages where I live. Every once in a while, we might get a dropout or spike, and it will kick in my battery backup system for my computer. It sounds an alarm, so I get notified even on the shortest disruptions. Most of our power outages have lasted less than maybe 15 minutes. So, I have never invested in a larger battery backup home system or generator setup. Even for our recent (once in 40 years) 12-hour outage, we were able to get by with just my small 18v inverter and using my tool batteries.Well, those are my fresh thoughts just having come off a power outage. Hope some of those inputs will help.
Well, sucks, I was a bit off target! My chicken coop does not need any electricity in the non-winter months. I have a ~125-watt base heater for the waterer which I use in the winter. But natural light is provided by windows. I suspect your solar battery bank would probably have enough power to provide lights and water heater power for days, or weeks, depending on how much sunshine you get. I don't use a heater in my coop ever. My chickens have survived fine even in -40F degree weather for a short week. But if you want to maintain a heated coop, that would be the biggest draw on your battery bank.
BTW, where did you get your LiFePO4 batteries? None of our local shops will sell them. I would have to order one from 
