How cool are the typical overnights?
www.seer2.com
You have to size the inverter for the loads it will carry.
I have a 9k and 12k Della splits. The 9k uses around 220w average on the lowest fan speed. Some times it goes lower. I have it in a section with the bedrooms that is insulated from the rest of the house. Its easy on the batteries and takes the edge of for sleeping in the summer nights.
I'm going to use one of my unused transfer switches to power my 24k unit so if the DC runs low I can use my inverters....unless my inverters are overloaded, then I can switch over to gird AC. I am hoping for a zero dollar grid bill soon. Now I am only cutting it in half.
I have three Eg4 6000's and four EG 4 Lifepower batteries. My current 5 ton unit went out. I would never have been able to run it off grid. So, saw this as an opportunity to get the 24k unit going for now in my living room and kitchen/dinning area and if it works well, add the additional 12k units to my bedrooms. Hopefully I can run these with a few extra panels seperate from my 24 panels that run the rest of the house. Don't know if I ran everything through the inverters if I might run into an overload situation on extremely hot days.
SEER ratings is quite defined, I’m sure some manufacturers take liberties with reporting (similar to car companies doing their own EPA mileage testing, here’s looking at you Porsche/Audi/VW https://www.reuters.com/business/au...economy-claims-500000-us-vehicles-2022-06-16/)
Also be in the look out for SEER2 and other DOE required changes for 2023.
SEER2 New Efficiency Standards
The Department of Energy (DOE) is changing the way HVAC systems are tested. By January 1, 2023, SEER2 product regulations will be in full effect. Learn what this means for your region.
And you lose how much of the energy you collected, through your inverters…
I think the "best case" for skipping DC-AC is anything close enough to the batteries that is already running DC. The farther away the more line losses (and/or the expense of cable) become an issue.10%-ish.
Given the flexibility and choice of AC powered options and the higher cost and reduced availability of equivalent DC powered items, I have never found a case where the increased cost of the DC item justified saving that 10%. In a tight system, sure, it's worth considering, but if you're trying to run a mini-split, you'd better not have a tight system.
I’m thinking if I had 32kwh of battery I’d likely just “inverter up“ ? and go with a normal 120 or 220 AC powered mini split unit due to initial ms cost savings and simplicity.
