RioRand (TM) 60A 12V 24V 48V ViewStar VS6048N EP PWM Solar Charge Controller with lcd display The RioRand Solar Controller, or solar regulator is similar to the voltage regulator in your car. 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. Not always, but usually. Generally, there is no need for a Solar Controller with the small maintenance, or trickle charge panels, such as the 1 to 5 watt solar 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, such as the Concorde Sun Xtender then you can use a smaller 2 to 2 watt panel. The RioRand Tracer PWM Solar controller adopts PWM technology (Maximum Power Point Tracking). The advanced tracking algorithm make the solar module operate at ideal voltage which the solar modules can produce the maximum available power. Compared to conventional PWM controller, PWM technology increase charge efficiency up to 30% and decrease the power of solar array needed. The RioRand Tracer PWM Solar controller has the ability to step-down the higher voltage solar array to recharge a lower voltage battery bank. Max. 150VDC input. So it allows on grid solar modules or thin film modules to charge the off-grid battery. And the cable size can be reduced because of the small current from the solar array. The RioRand Tracer series PWM controller is for off-grid solar system and control the charging and discharging of the battery. Tracer PWM Solar controller features a smart tracking algorithm inside that maximizes the energy from the solar PV module(s) and charge the battery. At the same time, the low voltage disconnect function (LVD) will prevent the battery damage from battery over discharging.