Hybrid Charge Controller Structure

Dear all,

I need to design a hybrid charge controller that functions off a Solar PV and the Grid, while prioritizing the Solar Power.

The specs are as follows: Vmpp = 18V, Impp = 3.5A.
Target Battery is a 12V/26Ah battery, that is used to power up a load consuming 2A continuously.

The objective is to keep the BOM cost minimal, hence trying to avoid the use of relays in design.

Since power from the grid would be designed from a fixed output SMPS, there wouldn't be any way to regulate the amount of current flowing through the grid branch. I saw in some literature where they had placed a diode between the battery and grid to control the current sharing, however I couldn't find a valid explanation for it.



Is there any way to ensure current sharing between the solar PV and grid, while prioritizing the amount of current sunk via the grid, while MPPT runs on the solar panel?

Since power from the grid would be designed from a fixed output SMPS, there wouldn't be any way to regulate the amount of current flowing through the grid branch.

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Doesn't sound reasonable. I don't see why it shouldn't be feasible to regulate the SMPS output current to an appropriate value (intended battery charge current - Isolar). It's also mandatory to implement an end of charge voltage limit for both charge sources.