Hi Sorbari Akpea,
i think we see a good book title here!: (hey brother can you spare two hundred grand) subtitled: (how to have fun with fifteen thousand pounds of lead)
"Charge time = 0.4 (1.2 x Amp hours (of the battery being charged) / charge current)
Is this formula correct?"
that equation looks good..that one gives us a very optimistic 80% efficiency for the chemical conversion. seems that is the standard starting point...i find that battery based systems tend to run closer to the 50-60% mark at the end (in a good design!) after all the system losses
everyone comes to find their own methods for working through some of these calculations and perhaps others may have some tips on other methods...but for me i just seem to get into trouble when i attempt to work with units of amp hours (tend to make silly apple/oranges mistakes) i find it much easier to convert all units into watt hours as a first step.
how some of the numbers look from here:
999AH @ 200volts = 199,800 watt hours
40% discharge (60% remaining) = 79,920 watt hours used
79,920 X 1.2 = 95,904 to recharge back to full
95,904 needed/5 hours = 19,181 watt pv array (need to do the 80% thing again with that too!)
= 23 kw array
the good news is that if we use some power during the day while charging we get to skip that 80% chemical conversion thing and use it as it's being made..sort of..but those watt hours not going into the battery still need to be made up for with a longer charge time.
i hope this is a "paper" project and not an actual system.
have fun! dave