Table of Contents

MPPT integration

There are benefits from using higher voltage panels that can be realized when a system is designed for an MPPT controller. $/watt ratios can become quite favorable with large, used panels and overpaneled controllers.

The downside is that MPPT requires some amount of excess panel voltage over charging voltage to do its work (see below). MPPT advantage may be minimal or nonexistant when nominal panel voltage matches nominal battery bank voltage (12v panels and 12v battery, for example). Consider this worst-case scenario:

In this situation the controller can't do MPPT charging above 12.66v; we have effectively wasted our money on that expensive MPPT. So make sure there is sufficient (voltage) headroom for the MPPT to operate. This can be done with higher-Vmp panels1), higher-voltage panels2), or panels in series. Example: 2x 12v panels in series is nominal 24v, a great fit for charging a 12v battery bank.

input voltage

Input voltage is a balancing act between efficiency / heat reduction (requires lower input voltage), the ability to overcome self-consumption losses under all conditions (requires higher input voltage), wire size and length (higher input voltage), and shading mitigation (higher input voltage).

MPPT manufacturers always specify a maximum voltage coming into the controller; some also specify a minimum or optimium voltage for MPPT operation:

other uses

An MPPT controller can also be the centerpiece of a DIY converter.

1)
like high-efficiency mono panels
2)
20-24v