You need 800W panels. But question is not good. Also you need strong sun in 6h duration, that the panel could run at maximum power of 800W, or if sun is not to strong, you need more solar panel area to get that power.
This is high power required unless you are installing the set up in tropical areas there is very little probability of you getting this rate of power 365 days a year
Going for more solar panels is a solution you need to consider
Since you can't get full sunlight on the panels for the entire day, and assuming that you need to charge the battery from fully discharged to fully charged, in one day, you'd need about 1200W to 1600W.
One thing I have often heard from panel distributors is that, they "calculate" the panel required as such:
1) Roughly calculate energy stored in battery in VAh. In your case, this is (24V * 200Ah) = 4800VAh
2) Select panel power(W) as between one-fourth to one-third of battery energy (in VAh). In your case, it'd be between [(4800VAh / 4h) = 1200W] and [(4800VAh / 3h) = 1600W].
Of course, remember that this is a rough estimation made with many assumptions made. It is not any accurate formula or calculation, but they way the panel distributors decide which power rating panel to provide.