50W Photovoltaic Solar Battery Regulator 
The regulator was designed for a 10W to 50W 12V solar panel bit the electronics can be easily adapted for higher power.
A switching power supply (SMPS) module was added to reduce dissipated power and to improve efficiency (the original circuit was based on a 7805). This SMPS enables also the use of a 24V input voltage.
The charging of the battery is controlled by a microcontroller (MCU) that also cuts off the load when the battery gets discharged too much. When the battery is charged up to at least again 12V the load is automatically reconnected.
Final PCB revision 1.3c to correct some minor details.
Software revision 2.5.1, almost completely in English with many comments. This version expects T2 and T4 to be mounted.
Here are the lab notes:
P3, IC4, R16, C7 are for future use and are not handled by the software. If they are mounted, the ADC reference and thus the voltage measurements will be incorrect. > Read more
We have modified the PCB a little to make it fit nicely in the enclosure the author had chosen: Fibox MNX PC 150-50 LT. Also, we merged the connectors into one to make connections cheaper. Now you can use one 8-way or two 4-way or four 2-way (or two 3-way plus one 2-way but why would you want that?) plugs.