Maximum Power Point Tracking (MPPT) solar charge controllers are significantly more efficient than the cheaper Pulse Wave Modulation (PWM) solar charge controllers.. A true MPPT solar charge controller needs a large transformer coil and capacitors inside, it is a bigger heavier unit and will usually takes at least 100V-150V input.

An MPPT solar charge controller in cool conditions can produce 25-30% more battery charging power than a simple PWM controller and you can connect high voltage panels to lower voltage battery banks. By using higher voltage on the panel side will also benefit by less volt drop and can use thinner cables. On large arrays we run everything at 100V - 150V.

EPSolar charge controllers have established themselves for almost 10 years. We are offering their latest EPEver range of excellent value Tracer A series and iTracer MPPT solar charge controllers. Epsolar/ EpEver has passed ISO9001. All products have CGC-solar, CE, ROHS, FCC and ETL certificates and are sold in over 120 countries worldwide

Cheaper PWM charge controllers are a good low cost solution for small systems only. To fully exploit the potential of MPPT charge controllers, the solar panel array voltage should be substantially higher than the battery voltage and is generally recommended for systems of 100-150W and upwards. The MPPT controller enables higher PV system voltages which can then reduce cabling costs by allowing for smaller cable cross sectional areas. The MPPT controller will also harvest substantially more power when the solar cell temperature is low (below 45°C), or very high (above 75°C).

To calculate which size controller you need, take the peak solar panel watts and divide by the / battery voltage to give the MPPT rated charge current in Amps, for example 150W/12V = 12.5A, therefore a 20A rated charge controller is recommended.

Maximum PV Array input power - All Models

When the PV array is connected to the charge controller with correct polarity, the Max. PV Array Power must not exceed three times the Rate Charge Power.

These MPPT controllers have a limiting function on charging current to protect the components and circuits. They will charge the battery(s) within the rated charging power even if PV input power exceeds this range, for example

1, If the PV array output power is less than or equal to the rated charge power above, the controller will charge the battery(s) at the actual maximum power point;

2, If the PV array output power is greater than the rated charge power above, the controller will charge the battery(s) at the maximum rated power.

This should be taken into account when designing the PV array power output which may peak during summer months causing some surplus generation in off-grid systems. For larger PV arrays, this solar charge controller may only form part of the overall system where some of the power generation is channelled into battery storage and the remainder of power generation may have real time usage/ consumption.