40 amp to be on safe side

To be safe divide the solar watts by the battery voltage, 41.6 amps for a 12v system and 20.5 amps for a 24v system. This gives a 30% safety margin which is important because certain conditions can make a solar panel put out 100% or more of its rated capacity. Cloud edge effect near water/snow or sand where reflective glare is noticeable a panel can product 125% of its rated output. Most quality controller can handle that and/or have current limiting, cheap ones do not and the smoke will come out either rendering it dead with no current flow or punched through with no control at all. Many threads on these forums about batteries killed by a punched through solar controller so saying that never happens isn't the type of information that is helpful

T1 Terry

HI
solar only
Epsolar
Morningstar

dc/dc chargers and solar
Projector IDC 50amp
Redarc 40amp
Enerdrive 40amp

Need to make sure which ever controller u pick can handle the input wattage and voltage . Some controllers have specific requirements .

Most likely 500watts in a 12 v system = 27.5 amps ++ up to 30% for mppt = 8 amps bonus =total 35.5 amps . ideally a 40amp controller.