I like the napkin math, and if the ROI works better it's obviously a win. The question is how much you can you actually drop the $295 with the DC unit. The nice thing about a DC HVAC is it is likely to produce the most benefit when it is actually needed the most, ie when the sun is beating down cooking your abode, so you really can't go wrong over the long term no matter what you do. Let us know how it works out in reality. Panels are pretty cheap, but there is also the apples/oranges issue as to how much you would have saved just replacing with a high seer, less expensive vanilla AC mini-split. This is what makes this stuff interesting!
A tangent to why I prefer the DC:
Back on April 1st my Town in New Jersey experienced a rare Tornado. I was in my attached garage at the time. It sounded like a commuter plane had broken the sky and coming down... you know that sound. Then battering winds and crashing as the tree across the street took down 5 telephone poles like dominoes. My whole house started buzzing, then one of the transformer poles blew... and Bam! Sparks shot out of my breaker box like 3 feet and 2 light bulbs in the ceiling shot right out of the sockets! Very crazy, my Daughter and Wife were huddled in the Den screaming and crying and I was almost ready to get everyone under the crawlspace, as we have no basement, but the worst of it was over. 3 of my own trees down, one totaling one of my cars. downspouts and siding ripped off the house.
I was out of power for a week while they repaired the electrical lines and had an electrician replace my fried breaker box. but with the help of my little Lithium 200ah/200wPV Solar setup I really didn't skip a beat. We we able to watch TV, charge phones/ipads and have lights. All the necessities that keep you from going crazy like my neighbor. At night with the neighborhood completely quite and dark he could see my lights and TV thru my Sunroom into my Den and approached me asking if I had Solar and what was i watching? DVD's since the Cable and Internet was down?... He said his Wife was going nuts with no TV. I told him no. See those antennas on my roof. I'm watching local TV. He had no clue antennas still worked.
Anyway I realized the only things you really need in an emergency situation. Unfortunately I couldn't get my 1000w pure wave inverter to run my fridge. It would start to run and the then stop in like 30 seconds, but I didn't push it. In my situation we ordered out for a week and put ice in the fridge for cold beer. Insurance payed for my spoiled food.
Now luckily this was April, no need for Heat or AC.... So this brings me to why I'm sharing this. The other Necessity - AIR CONDITIONING. If this had been in the thick of Summer it would have been a completely different story. I wouldn't have been able to stay at my house.
So, I started looking into these DC Mini-Splits. Like I say in my situation I could get by with my little Battery system for emergency. But the Boyscout in me wanted the preparedness of having AC also. My cheapest out of pocket option (with a Kid in collage) was not to enlarge my system, but add on to my system.
As far as the the less expensive vanilla one, I think that's a negligible $400 bucks, and the Panels I could always repurpose in the future if I did expand my battery system.
so you really can't go wrong over the long term no matter what you do.
Your right here, no matter what you plug it into, Battery, Solar or Grid; Mini-Splits are gonna save you money. I just finally got the Lines outside, that's a whole nother story. Install is not for the faint of heart; cutting holes threw your house... Should be conecting the Lines this week now thats its bearable to work outside without heat stroke.
