Just testing how insane this is.
Take a mains feed, through a AC/DC power supply to produce 24V (regulated after beefy diodes). Feed this directly into the solar inverter input. Without solar power at all this should run the inverter, although a complete waste of time doing so.
However if the solar charged batteries are above 24V they will 'over power' the ACDC brick and supply 100% of the power to the inverter. When the solar batteries deplete below 24V however the ACDC brick will supply power to the inverter.
Surely this can't be that simple?
I wondered about if the solar batteries drop below 24V somehow, such as cell failure. Surely then the ACDC brick would just charge the batteries to 24V and as long as it's rated to be capable of doing that and running the load, but limited to something sensible this is not an issue?
What other issues does this kind of set up have, especially when compared with the alternative transfer switch solution?
I'm toying with the hobby grade idea of powering a 100W 24/7 365 from solar, but in a way that allows things to start small and slowly scale up modular fashion, eg, more panels, more batteries.
Oh, before there are suggestions of just grid tieing the inverter. In the UK I simply can't. To do so I would need to have the whole rig certified for grid tie and pay the cost of the micro-gen meter. Which would instantly make the whole thing to expensive. If I simply connect a grid tie inverter there is a potential I would run the clock work meter backwards and... that's considered a crime of tampering with the utility.