Controller for hybrid off-grid solar system

[yep]

Hi All, I'm setting up a hybrid off-grid solar system to power my home security camera system. The system consists with a solar panel and battery, during the day the system will run on solar and during the night it will run on battery that charged by the extra solar power during the day. In event of rainy days, when the battery is depleted, I want to automatically switch to line power for the system and charging the battery. The key is to automatically switch to line power only when battery is low or out, and switch back when battery is up to a certain percentage. Is there an existing controller that can do this (more ideally customizable switch condition)? Thank you.

 

[DThames]

Maybe this?

• This product is suitable for 12-24V MAX30V battery charging control, can be free to set the start charging voltage and stop charging voltage!
• Suitable for use in household chargers, solar energy, wind turbines.
• Input voltage: DC12-24V (MAX 30V). The maximum current can be controlled by 20A. (If the board is working for a long time, it is recommended not to exceed 15A)

 

[DJSmiley]

Might work for lead acid, but for lfp probably not.

You can use a victron bmv/smartshubt. Some of them have a relay which you can configure. You caneg enable/disable the relay based on a certain soc.
Some chargers have a remote on/off, for others you can add a relay which powers on/off the charger

 

[yep]

Thanks. Maybe I need two controller, one for switching between grid and solar, one for charging the battery. There are set points to set and I wish all can be taken care of by one module... Let me think more about it

 

[izmail]

I can suggest using TESO SG-2 programmable relay. It is a wonderful device, actually quite powerful PLC ( see link below). They make them 12v and 24v DC - ideal for solar system. 6 inputs, 4 outputs and 2 analog voltage inputs to measure battery voltage and more. I use it for exactly what you are describing. In my case it switches from solar to utility and back based on battery charge state. It also controls my pool pump. But only if you are familiar with PLC programming. Easy to learn though. Also keep in mind that in any case you also will also need an approved transfer switch to safely switch from grid to solar without possibility of frying the system in case of logic malfunction.
Teco SG-2