- sparrish 8 days ago
I think the 25 year payback quoted is way off. Those batteries are going to last 25 years? I doubt it. They'll have to be replaced at least a couple of times and that will increase the payback substantially.
- LinuxBender 8 days ago
Agreed. I would add that the inverter will not likely last 25 years with a high surge motor like a refrigerator attached to it, for most people anyway. I have not seen any step-start fridges.
- nikodunk 8 days ago
Hi! OP here. This was a user-submitted kit – so just calculating as is.
I'm constructing another kit based off this one which optimizes for payback period here https://sunboxlabs.com/shortest_payback/
But yes the battery payback is a problem. The discussion of the original article https://news.ycombinator.com/item?id=14821478 and the follow-up https://news.ycombinator.com/item?id=15425324 predicted this correctly: the original system with an undersized deep cycle lead-acid battery pooped out after a year. The Xantrex system above has way more extra energy storage, so it shouldn't get discharged completely as often (or ever). This should extend the life of the system, though 25 years is a stretch, yes.