In general maximum charge rate on flooded lead acid (FLA) batteries is 10 to 13% of the C20 amp hour rating. So for example a 100 AH (20hr) rated battery max charge current is 10 to 13 amps.
The sealed lead acid (SLA) is not so clearly defined as FLA. In the SLA family there are two basic types Gel and Absorbed Glass Mat. We don't recommend Gel batteries as they are not well suited for Renewable Energy applications.
In the AGM family it really depends on the manufacture. For example Trojan line can be charged as high as C/5 rate. While others can be charged as high as C/1, and at the other end of the spectrum no higher than C/20. So with respect to AGM, it depends on manufacture and model.
In all cases we recommend contacting manufacturer to determine recommended charge rates.
Here is an example if you had a solar array size of 2250W going to a grid tied system with battery backup using AGM C5 battery bank of 48VDC.
The charge rate from the solar panels is going to be about 46A, the recommended charge rate for AGM maintenance free batteries is C5 which is 5 x 46A. Therefore minimum battery bank size is 230AH. Four x 250AH Group 8D sealed AGM batteries will provide up to 9.6kwhs for your back up energy needs ( this is a 80% depth of discharge but because this would only happen on occasional basis it is no problem, normally with off grid systems it is the other way round and 20% is the optimum depth of discharge for longer life) There is the ability with most grid tied systems to reduce charge rate so that a smaller battery bank could be used but this would reduce your sell back to the grid also. It would be easy to add another 2 strings of batteries to the system in the future to increase back up power.