Charge Controller Options for Solar Air Conditioner
The HotSpot DC4812VRF solar air conditioner always connects to a 48v battery plant. The battery plant typically consists of multiples of 6v or 12v batteries wired in series to produce a 48v string system. For example, you could use 4 x 12v or 8 x 6v (golf cart type) batteries. Then each of these battery strings could be paralleled with a duplicate string to increase the amp hours and still be at 48v.
Connecting the batteries to the solar panels is a component called a charge controller.
There are two technology options for charge controllers, you would select either PWM (Pulse Width Modulation) or MPPT (Maximum Power Point Tracking).
The PWM type is very low cost but has less efficiency, particularly in colder climates. When a battery is charged to rated voltage, the charge controller must begin limiting the amount of current into the battery so that voltage is maintained but not surpassed. PWM sends power to the battery with pulses of a varying width, wider pulses allow a greater percentage of the input current to flow into the battery. The PWM option would be the Morningstar Tristar TS-45. This is a full featured 45a PWM charge controller that is available with remote meter and/or temperature sensor.
The other type, MPPT controllers, extract the maximum power from solar panels, but cost more. MPPT controllers use an algorithm to track the PV panel performance and manages the PV panel voltage based on the maximum power point. It checks the PV output and compares it to battery voltage, then makes adjustments to the voltage to input the maximum current into the battery. MPPT forces PV module to operate at voltage close to maximum power point to produce maximum available power. While we recommend MPPT controllers, we do offer a low-cost “budget option” of a PWM controller with our entry level solar air conditioner package. You can see several pre-configured solar AC packages here.
For maximum power utilization in a solar air conditioning application we recommend MPPT charge controllers and we offer the Morningstar TS-MPPT-45 and TS-MPPT-60 charge controllers for this purpose.
Here is a link to the Morningstar String Calculator
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