Maximum Power Point Tracker
In order to get the highest amount of energy from the solar cells, a so called Maximum Power Point Tracker (MPPT) is required. A MPPT is basically a DC/DC converter with variable and adjustable gain. It contains electronics that will monitor the current and the voltage of the cells and battery. By changing the gain, it will ensure the best use of the solar cells energy.
The current version of the MPPT has a weight of 22.5 grams and can convert up to 90W with an efficiency of up to 97%.