Blog - Solar regulators

FAQ: Never disconnect the battery from the solar system in operation

Question: One of your support articles says the charger should not be connected to the battery permanently. Does this apply for the DC solar chargers (MPPT regulators) as well?

Answer: No. The support article gives the advice in relation to AC powered DC chargers, most of them are not designed to be connected to the battery permanently. We strongly recommend to monitor battery charging when using the AC/DC battery chargers and to disconnect the chargers after  the batteries are fully charged.  See the explanation here.

On the other hand, the solar charger controllers (MPPT regulators) are designed to be connected to the batteries permanently. They are a completely different type of product, and for a proper function of the solar system the battery must be permanently connected in the circuit.

Warning: when using the DC solar charger controllers (MPPT regulators), keep in mind that these controllers will be damaged if the battery is suddenly disconnected from the system that is running at full solar power. If there is a need to disconnect the battery, the solar panels must be disconnected first, the load must be disconnected as well, and only when there is no supply (input) and no load (output), it is possible to disconnect the battery.

If the battery is suddenly disconnected when the DC solar charger controller is operating, the internal circuits of the controller may be damaged (burned) without the possibility to repair under the warranty terms!  

Summary: with the DC charger controller the battery is not allowed to be disconnected under the load or during charging.

Note: keep this information in mind when designing a BMS system for a solar battery pack. In case of irregular  condition of the battery pack, the BMS should not „hard disconnect“ the battery from the system, it should fist turn off (shutdown) the input and out put of the controller and only after this kind of stopping the system, the battery may be disconnected  in consequence.