Solar panel voltage regulator

An intrinsic component to any solar power electrical system is that of a solar panel voltage regulator. Such a regulator is a vital necessity to prevent the solar panels from overcharging your storage batteries. A solar panel voltage regulator will keep your batteries in a safe operating range. It should perform two functions:

  • Protect your battery(s) from overcharging when the sun is at it’s strongest
  • Protect your battery(s) from excessive discharge in bad weather

Each of the above situations can harm your battery{s} if a solar panel regulator is not installed as part of your solar power electrical system. Even a very small solar panel can damage a battery and boil away the electrolytes. Replacing the battery(s) in your solar power electrical system is costly. There are self-regulating solar panels that are less likely to overcharge your battery(s).

A solar panel voltage regulator is typically wired between the solar panel and the battery bank being charged. The regulator will disconnect the solar panel from the battery when it is fully charged. It will automatically re-connect the battery to the panel with the voltage in the battery drops. It is important regulate the voltage on the battery because a solar panel can drive the voltage higher levels and burn out the battery.

Solar panel voltage regulators have set points that can be either fixed or variable. Some will have indicator lights that will let you know if the solar panel is charging the battery or not. A very simple and basic solar voltage regulator will not have indicators and will have a fixed set point. An advanced regulator will have a digital LCD display that will show the battery voltage, when it is charging current, loading current and when current is being discharged. Some will allow “Load Disconnect” allowing the removal of any drain from the battery if the battery voltage drops too low.

A linear series solar voltage regulator has the disadvantage of allowing power consumption when the sun is at its weakest and will cause a voltage drop in the battery.

Most solar panel voltage regulators use shunt linear series regulators. Shunt solar voltage regulators are usually On/Off regulators that are mostly used for commercial units. A shunt voltage regulator will use a transistor switch or a MOSFET switch that will short out the solar panel until voltage drops. When the voltage drops below a certain level the solar panel will be turned on again. This type of solar panel voltage regulator is inexpensive but it has major disadvantages. This is because the voltage power output will always be fluctuating between 13v and 14.5v, meaning that the battery will be continuously cycling between overcharging and discharging. This can reduce the life of the battery. More importantly, if there is ever a battery failure, this type of solar voltage regulator will cycle rather quickly, causing full panel voltages to be applied. The danger of this is that sensitive equipment that is being powered by the system can be destroyed. However, a linear shunt solar voltage regulator will burn off all excess energy from the panel and keep voltage output constant. You can get a battery life of five years with this type of solar panel voltage regulator.

A pulsating regulator will only give you 2-3 years of battery life but is also a good choice. This solar panel voltage regulator will chop up input power and send it through a step up transformer and internal capacitor, then discharge a pulse of energy to the battery. A pulsating solar panel regulator is more efficient than linear regulators and many people prefer this type over other types of solar voltage regulators.

One Response to “Solar panel voltage regulator”

  1. Jim Says:

    We get snow in the winter, so I was going to disconnect my batteries,since the solar panels will be covered in snow and not charging.At nite my regulator show a red light,that states the batteries are low. I checked the batteries and they showed 13.88 volts. I don’t want to ruin the panels or the batteries,thats why I thought of disconnecting them and putting them somewhere warm. Can you give some advice on the subject.