I converted a motorcycle to electric (72VDC / 6.5kWh battery and 8kW hub motor) I have a DC port which connects the pins via a contactor to the battery. The contactor opens when the BMS detects when one of the cells reaches top voltage. I simply plug in 3 24V Solar panels in series (=72V ) to charge the bike. This way the typical DC/AC and then AC/DC conversion can be avoided. There are two ways of doing this:
1) Simple direct port, like on my motorcycle.
2) Design a solar charge CCS interface. This way you connect DC to the battery in using the CCS protocol but instead of grid power you have an array of solar panels matching your DC system voltage.