Questions on Solar chargers

[dynamag]

Hi
I am looking at designing a solar panel based lead acid battery charger. Say I use a 19VDC panel of 75Watts Peak. I am looking at getting the maximum output from the panel into my battery, so I think I should try to use MPPT in my design. I am going in for either a non-inverting buck-boost converter or one of he capacitor coupled converters such as Cuk or Sepic for my design. I need to measure the power flow from the panel with my uP, and that involves generating 5VDC. I also need to drive my MOSFETs with gate drive circuits that will require 12VDC or so to make the MOSFETs switch properly.

Should I use the battery to generate the 12V? or should I use the panel to generate it? The same question for the 5V also.
Should I use a simple 7812+7805 based linear regulator to get my dc voltages? Is there any other, more efficient method available?

These may be very basic questions, so I thank you for your patience with me.

 

[tpetar]

Hi Dynamag and welcome to EDABoard,

For measuring You can use Hall sensor ACS712, A1302, or any other similar. Power supply for circuit should be done using switching tech, 7812, 7805 is linear and will make some power loss according to circuit design and needs.


Best regards,
Peter

 

[chuckey]

dynamag, where are you?, its just that in the European winter, there could be days and days of zero solar charge, so you don't want to load the battery with the micro power supplies. I would design a circuit with a micropower real time clock/calendar so that in the winter the micro is turned on for 1 minute every hour during the hours of daylight. If during this time the battery is actually charging, then the micro over rules the RTC and stays active and hopefully some real power charging occurs.
Frank

 

[dynamag]

dynamag, where are you?, its just that in the European winter, there could be days and days of zero solar charge, so you don't want to load the battery with the micro power supplies. I would design a circuit with a micropower real time clock/calendar so that in the winter the micro is turned on for 1 minute every hour during the hours of daylight. If during this time the battery is actually charging, then the micro over rules the RTC and stays active and hopefully some real power charging occurs.
Frank

Thank you for that, Frank. I am in India, so no insolation issues here, plus the system already has an RTC built in.

Peter, Thank you too. I will look at those current sensors.