What does a Solar Regulator do when the battery is full?

davecladavecla Registered Users Posts: 8
I've got a Solum Solar Regulator - pretty sure it's this one:
http://www.amazon.co.uk/Solar-Charge-Controller-Solsum-6-6F/dp/B0090K347C

What does it do when the battery is full - does it shunt the input from the solar panel across a resistive load or just go open circuit?

Thanks in advance,
dave

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,013 admin
    Re: What does a Solar Regulator do when the battery is full?

    I believe that one is a "series" PWM regulator. It just turns the solar panel on and off -- Just like flipping a light switch. On--the panel charges the battery. Off--the panel stops charging the battery. Flip the switch (transistor) a few 10-100 times a second--and you have a PWM controller... If the switch is on 100% of the time, full charge. If the switch is on 50% of the time, 1/2 charging current. If the switch is on near 0% of the time--charging completed and no current supplied.

    As far as I know--Steca is a high quality manufacturer.

    There are some very old stye (typically small) shunt type solar regulators that actually short out the solar panel (as I recall). But there is really no reason to do that.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PNjunctionPNjunction Solar Expert Posts: 762 ✭✭✭
    Re: What does a Solar Regulator do when the battery is full?

    Yep that is a pwm controller with series control. Look out for counterfeits so make sure you deal with a reputable outlet. Avoid deals too good to be true.

    And of course follow the advice to connect the battery first, and the panel last when installing.
  • RCinFLARCinFLA Solar Expert Posts: 1,398 ✭✭✭✭
    Re: What does a Solar Regulator do when the battery is full?

    As to where the solar power goes, the controller goes open circuit and the power goes into the PV cells. Since the PV cells are only 13-15% electrical delivery efficient it does not cause much more heat dissipation in the PV cell.

    The inherent diode that is the PN junction of the cell just goes into forward conduction and the illumination generated current just goes back into the PV cell. Panel goes to Voc.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: What does a Solar Regulator do when the battery is full?
    RCinFLA wrote: »
    As to where the solar power goes, the controller goes open circuit and the power goes into the PV cells. Since the PV cells are only 13-15% electrical delivery efficient it does not cause much more heat dissipation in the PV cell.

    The inherent diode that is the PN junction of the cell just goes into forward conduction and the illumination generated current just goes back into the PV cell. Panel goes to Voc.

    Not really, IMHO. When there is no place for the charges separated by the PV action to go, either that particular photon absorption mode no longer exists or the liberated charges just recombine.
    Note that as RC said the amount of energy that does not leave the panel as electrical energy is just a small fraction of the incident energy which is represented by the incoming solar radiation.
    One interesting quirk is that if you short circuit the panel, that same amount of heat is effectively dissipated in the form of resistive heating inside the panel.
    So if you are interested in keeping the panels cool, both open circuit and short circuit will leave more thermal energy in the panels than loading the panel to its MPP. :)
    SMA SB 3000, old BP panels.
  • Dragonlady5Dragonlady5 Registered Users Posts: 19 ✭✭
    Re: What does a Solar Regulator do when the battery is full?

    PWM controllers switch the panel ON and OFF, depending on how much energy is available and how much the battery bank needs to keep it at the float Voltage (or any other regulation Voltage absorption or equalization, -the same thing occurs) the pulse width, or duty cycle will vary. Can be ON for as little as 1-2% and even 0% when float stage is first entered.

    When the controller switches the panel OFF (open circuit), there is no current flow, so the power does not go into the cells, it ... doesn't go.
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