MPPT Solar Charge Controllers

MPPT solar charge controllers are used when the voltage of the solar panels is significantly greater than the required charging voltage. For example, if you wish to use a 200W grid-tie panel to charge a 12V battery, the voltage of the panel will be about 30V and 7A, but the charge voltage for the battery only 14V. In this case, if you use a standard PWM controller, when the voltage is reduced, the power production in watts also reduces (from 200W to about 100W).

MPPT controllers overcome this problem by being able to optimise the charge voltage and current, not just changing the voltage as PWM controllers do. To do this, MPPT charge controllers typically store charge within them and boost the current of the charge output as and when needed, optimising the available power input with the charging output. By doing this, they are able to increase the amount of charge current by up to 30% (dependent on the degree of voltage change required). MPPT charge controllers are, however, more expensive.