Barn Solar Power Room

[Gopirque]

I’ve combed through the forum a bit but with new tech coming out I need some advise on my situation. I’m looking to DIY a solar offgrid system for my barn to run all my loads. Winter time it’s mainly tank heaters and lights, summer it’s mainly tools, milker, and lights. I‘m heavily considering the eg4 6500ex inverters (2) paired with trophy LiFePo4 48v 110ah batteries (15-20kwh total) i’m leaning trophy because of their internal heaters and it gets -25F at night several nights a year. My plan is to put the batteries and inverters in a 10x4 insulated room in the barn.

My challenges/questions:
1) will the ambient temp from the inverters be enough to keep the room warm enough during cold nights, when they will be working the hardest?
2) if i use a Little Buddy heater (propane), will there be too much condensation if it’s used sparingly?
3) should I consider a different inverter? I’m trying to balance value and utilization…
4) other practical options for a completely offgrid situation…

Thanks!

 

[OzSolar]

Welcome!

Just making sure you've done the math on the tank heaters. How many kWH per day do they need? Heating things with solar can be dicey. EG: the peak need is opposite the peak resource. Short cloudy days and long nights result in very little energy to spare.

1. Hard to tell. One tid bit is that if your inverter is the typical ~90% efficient and making 3,000 watts (two tank heaters?) then you've got 300 watts of heat being wasted into the space.

2. Probably be just fine

3. I don't have any experience with that inverter

4. A completely off grid situation should always have a generator sized large enough to handle the critical loads while charging the batteries the highest amps they can take.

 

[Gopirque]

Thanks for the response Oz, I typically run 3 tanks heaters, a couple heated buckets, and some LED lights in the animal sheds over winter. Since all of the heaters are intermittent/on demand it’s a bit tough to get any solid numbers. My estimate is 3-4kw/h max load (hopefully). I have a few generators and alternative power available, but the intent is to run the barn off grid. I’m oversizing the inverters because next spring I want to put a well in the barn as well as be able to run my power tools and milker off of this system.

 

[mvonw]

I've got a bank of 6 Trophy batteries that are housed in small closet that I insulated with multiple layers of air-gapped Reflectix and 2 layers of 2 inch foamboard insulation (IOW, lots of insulation). I have an internet controlled thermostat that controls a small 200 watt space heater in the closet. It hasn't gotten below 25F yet but I the little heater keeps it stable at my 58F set point. It will be interesting to see how it does at -25F. I will probably just put in 500 watt space heater if it doesn't. I used a thermal camera to look for heat leaks, this has been super useful (get one). My Sol Ark 12k dump load is wired to 240volt space heater that heats the shed that the batteries and inverter is in. I've got 20kw of panels, which typically produces way more than I need on reasonably sunny days. In winter, I have short cloudy days, so I need a lot of panel capacity.

My generator is a propane converted Honda 6500is, which doesn't come close to the 140amps that I charge the battery bank on solar, but it's fantastic on topping off the batteries on cloudy days. This will be an interesting winter to see how the batteries do with the built in heaters and the supplemental heated closet.

 

[OzSolar]

I used a thermal camera to look for heat leaks, this has been super useful (get one).

Which one did you get? Are the ~$300 ones any good?

 

[mvonw]

Which one did you get? Are the ~$300 ones any good?

I got a Uni-T unit, only because I've used some of there other equipment and they've been good. This one was $500, which seemed quite pricey. I've found a lot of thermal leaks in my solar shed with it and used it to double check my electrical connections. I bet the $300 ones are fine. Video really isn't that important. Being able to take photos is useful because I can compare shots after I've made remediations. It's one of those tools that you don't use often, so it's hard to justify, I know.

 

[OzSolar]

Being able to take photos is useful because I can compare shots after I've made remediations. It's one of those tools that you don't use often, so it's hard to justify, I know.

Thanks! A person can fool around and end up with shop full of tools that they only use once or less per year if they're are lucky ha! To combat that I've taken to renting a lot of tools. A few buddies and I have banded together in effort to form a tool and vehicle co-op. EG: I'll buy the $1500 Hilte, you have $2500 wood splitter. It sort of works but it eventually the tool is never at the place it's needed at the moment.

 

[mvonw]

Thanks! A person can fool around and end up with shop full of tools that they only use once or less per year (if there are lucky). To combat that I've taken to renting a lot of tools. A few buddies and I have banded together in effort to form a tool and vehicle co-op. EG: I'll buy the $1500 Hilte, you have $2500 wood splitter. It sort of works but it eventually the tool is never at the place it's needed at the moment.

Ha! Don't I know it! How many times I've wanted to buy a box blade for my tractor to level my driveway, but couldn't justify $5k for something I can rent. When I do buy, I usually buy top end stuff, not because its better but because I'm a man.

 

[Gopirque]

I got the batteries and some hardware today, waiting on the rest to arrive hopefully next week. I opted for an additional battery vs the 2nd AIO because I don‘t really see myself pushing the 6500 anytime soon. Will keep you posted how the build goes.