Won't the battery will be fried if charged till 15v?
Probably the battery is like a car battery. The regulator limits the voltage to 14.5 volts. (more or less)
If you have a car with a real voltage meter on the dash; In the morning the battery voltage is 12V and full charged. When the motor is running well (charging) the voltage will charge to about 14.5V.
Also How will you explain 12v 40A and 750Wp?
12v X 40a = 480 watts.
18.9v is the panal voltage... I forgot in pwm power is wasted a lot... so 18.9 would become same as battery voltage once connected to it.
Assume 100% efficient: (PWM)
18.9V at 10A
in will give you 12v at 15.75a
out
18.9v X 10a = 189 watts, 12v X 15.75a = 189 watts
A PWM is much like a gear ratio in a transmission. If you reduce the RPM you get more torque. If the speed of the shaft is reduced 2:1 then the torque is 2x more. (if no loss in the bearings)
-------------------------------
18.9v X 10a = 189 watts, 12v X 15.75a = 189 watts at 100%
12v X 15.75a = 189 watts - 18.9 watts of loss in heat = 170 watts.
OR
15.75A - 1.575A of loss = 14.175A
>>12v X 14.175A = 170 watts
----------------------------
A linear regulator looses energy on purpose.
18.9V at 10A in and 12V at 10A out. Heat loss = (18.9 - 12 = 6.9v) X 10A = 69 watts of heat loss.
A PWM regulator tries to conserve power not wast power.
If 90% passes through then 10% is lost in heat. ( not on purpose)
170 watts in and 153 watts out. or 17 watts of heat.
A PWM is real good if the voltage of the panel and battery are very different.
24V panel 12V battery
A linear supply will loose 50% of the power.
A PWM will loose 10%.
48V panel 12V battery
Linear will loose 75%, keep 25%.
PWM will loose 10%.
Hope this helps
RonS