A charge controller, or charge regulator is basically a voltage and/or  current regulator to keep batteries from overcharging. It regulates the voltage and current coming from the solar panels going to the battery.  Most "12 volt" panels put out about 16 to 20 volts, so if there is no  regulation the batteries will be damaged from overcharging. Most  batteries need around 14 to 14.5 volts to get fully charged.


Generally, there is no need for a charge controller with the small maintenance, or trickle charge panels, such as the 1 to 5 watt panels. A rough rule is that if the panel puts out about 2 watts or less for each 50 battery amp-hours, then you don't need one.  For example, a standard flooded golf car battery is around 210 amp-hours. So to keep up a series pair of them (12 volts) just for maintenance or storage, you would want a panel that is around 4.2 watts. The popular 5 watt panels are close enough, and will not need a controller. If you are maintaining AGM deep cycle batteries then you can use a smaller 2 watt panel.

Sansata Technologies


With Solar Charge Controllers ranging from the regulation of 6 amps for lower power scenarios like a single light, to the full-system PT-100 offering MPPT while regulating up to 100 amps, the Sensata Technologies line of charge controllers has the right controller for your needs.

Need to divert AC energy loads for your AC-coupled system? The ACLD-40 Load Diversion Controller is your answer.

Outback Power

A charge controller’s main function is to optimize a PV array’s output which can fluctuate based on shading and temperature variables found on the average roof. OutBack's industry-leading Maximum Power Point Tracking (MPPT) charge controllers offer customers the same reliability and durability built into every OutBack product. Innovative solar harvesting and battery charging algorithms allow customers to maximize system potential and increase renewable energy yield by up to 30 percent.

As the industry’s first multi-voltage MPPT charge controller with a landmark design, OutBack’s FLEXmax Series is the most recognized controller on the market today. FLEXmax Controllers support a wide variety of system designs, battery chemistries, and integrate seamlessly in terms of system data management and programming.

Schneider Electric

MPPT multi-stage charging, better battery life
The Conext™ MPPT 60 150 is a photovoltaic (PV) charge controller that tracks the maximum power point of a PV array to deliver the maximum available current for charging batteries. When charging, the MPPT 60 150 regulates battery voltage and output current based on the amount of energy available from the PV array and state-of-charge of the battery.