Solar regulators for RVs accept whatever output is produced by the solar array. They optimise that to whatever needed for optimal battery charging. Most solar regulators for RVs also accept input from the RV’s alternator.
Most such regulators thus monitor both solar and alternator voltage. They switch routinely to whichever is greater. The more upmarket RV solar regulators have Multiple Power Point Tracking (MPPT). This ‘juggles’ solar module amps and volts, optimising battery charging. Ultra-cheap such regulators may claim to have MPPT. Most do not.
The essential RV solar regulator ensures your RV batteries safely and fully charge. The regulator accepts the varying voltage from solar modules. It converts that into whatever it deems most suitable for charging the batteries used, however, only a few are suitable for charging LiFePO4 batteries. Be wary re this because RV owners increasingly use them. For those, consult the battery maker.
Solar Regulators for RVs – dc-dc alternator chargers
Many vehicle dc-dc alternator chargers accept solar input. If you have one – that’s all you need apart from an energy monitor. Most good chargers have such monitoring.
Solar regulators are made in various capacities. Yours must handle the maximum solar current or alternator charging current. You do not, however, need to allow for the two combined. Battery charging does not work that way.