[damien c]

Investing the money might yield more than buying a battery system and running it, but what you can do is buy the system and save money each month from your electric bill, then invest that money if you wanted.

I have worked out that it's costing us around £6 per day for my server rack, depending on load.

If I can remove that from the electric bill by spending £1000 roughly, it would take around 13 months to pay that back, but the thing is, that would also drop because if I can output up to 800w from the battery into the mains in the house, we could end up with almost a £0 an hour bill unless the load on the house goes above that 800w.

Let's say that saves me the roughly £180 a month, we could invest 50% of that each month and then see what happens but for now, it's just hypothetical because I currently don't have the cash for it as it is, I am getting closer but not there yet.