Solar Charging and Amp Hours
Is the amperage from a solar panel constant as the battery it is charging charges up? I.e., as your battery reaches full charge, the current drops to zero either via the charge controller or the eq...
Forum Discussion
DarkSkySeeker wrote:
Is the amperage from a solar panel constant as the battery it is charging charges up?
ignoring changes in sun, temp etc the answer is yes. At a given set of conditions the IV curve of a panel shows the amps nearly constant over a wide range of voltage. A PWM controller lets the panel connect directly to the batt and all the power goes to charging UNTIL a set pt voltage of the batt is reached and then the controller begins to regulate power to the batt not letting the battery exceed the st pt voltage. Less and less power is needed as the battery tops off.
If sun, temp etc conditions stayed the same over time then the charging amps would be the same, say a 100w panel 'makes' 5A, then the 12v battery would get 5A (60w) and later would get 5A @ 14v (70w).(watts = v * a)
A mppt controller forces the panel to operate @ the mppt (16-18v for a '12v' panel), the power would be constant if conditions stayed the same, more amps into a 12v batt than a 14v battery (A=W/V). At set pt voltage, the controller limits power to maintain set pt.
During regulation (at set pt voltage) excess power is available for other uses or is never produced.
changes in conditions changes solar output power
below is the effect of light variations
