Solar Charge Controller (or Regulator) is a device which protects the batteries in a solar electric system from being overcharged or being over-discharged.
Overcharged batteries have a much shorter life time than well cared for batteries since the electolyte is boiled off as gas and lost. Overly discharged (i.e. flat) lead acid batteries become permanently damaged, so a solar charge controller is used to disconnect any load when the battery is discharged down to a safe cut off voltage.
LEDs and (in the more expensive regulators) LCD displays are used to show the current state of the charge of the battery, the state of the current entering the batteries from the solar panel(s), and the current being drawn from the battery by loads.
A charge controller is not always required if the maximum current going into the battery is not more than 10% of the batteries Ah capacity (C/10) - i.e. if the battery is 60Ah then a charge controller is certainly required if the current from the solar panel is likely to exceed 6 Amps - as long as you make sure you don't over-discharge the battery.
Some suggest a charge controller is required if the maximum current from the solar panel is just 1% of the Ah capacity (C/100) of the battery bank.
By using a solar charge controller or regulator with your PV system, you can easily control the flow of electricity to and from a solar power battery, thereby regulating its charge and discharge. This helps to maximize the lifespan of your costly storage batteries.
Draining a battery completely, or overcharging it repeatedly, would greatly shorten its useful lifespan. A programmable battery charge controller prevents that from happening by allowing you to safely manage the discharge level. This article explains how it works.
When the battery discharges to a certain level, the controller cuts off any further current drain to prevent the stored electrical charge from falling below the designed-in level.
Most controllers are factory designed to prevent deep cycle, lead acid batteries from discharging more than 50% of their capacity, thereby ensuring a longer lifespan.
For example, by programing the controller to stop at 50% depth of discharge, it will stop providing electrical power to the household when the battery is 50% drained, thereby extending its service life.
It also cuts off current flowing from the PV panels to the storage battery once it reaches a pre-set level of electrical charge stored to prevent damage from repeated overcharging.
Completely draining all the power from a storage battery regularly can cause it to lose capacity and shorten its lifespan from 7 or 8 years to only 2 or 3, or maybe less. Having to replace solar storage batteries every couple of years will drastically decrease any energy savings you gain from your solar power system.
Quality PV panels will last 20 years or more, but even good deep cycle batteries may only last 10 years. Having to replace them prematurely increases the cost of the overall system. So, the key to keeping your solar investment as low as possible, is by using a quality solar charge controller to maximize the lifespan of your battery bank.
Efficient solar battery storage is essential if you wish to remain off grid and run electrical appliances in your home on cloudy overcast days and at night when your photovoltaic (PV) panels cannot generate sufficient electrical power. That's because photovoltaic panels can only generate electricity when they're directly exposed to sunlight.
However, today's busy lifestyles don't allow us to stop using electrical power once the sun goes down or during periods of bad weather, so we need to have a practical backup power plan in place. This article explains what is needed.
Connected between your PV panels and the batteries, you'll need a battery charge controller to help regulate the flow of electricity to and from your bank of solar storage batteries and maximize their service life.
The size of the solar storage battery bank needed will depend on the size of your home or building and its daily power requirements, and the size of your installed PV system. You will need to determine your electricity needs by averaging the previous year's utility bills. Calculations of this sort will help determine your battery needs.
Storage batteries are expensive. When installing solar power, there is an initial cost quoted for the system, so be sure that all the components you need are covered in the estimate for the best pricing.
Some installers quote a price that includes your solar power inverter, your solar storage batteries, and your charge controller, but this isn't always the case. Make sure everything is included to avoid surprises.
You might not need a battery backup system in place. It all depends on whether you want to install a fully operational off grid PV system, or just a partial one.
For instance, you could remain grid tied and simply connect automatically to the power grid after sundown and use electricity from the local power company as your backup power source.
Or, if you plan to sell your generated surplus power back to the electrical utility by taking advantage of a Feed-in Tariff (FIT) program, you won't need backup power storage at all.
Storage batteries would be optional in such cases, though you might wish to have a standby generator connected for those unexpected times when there are prolonged power outages and your battery charge is low.
Good planning will help determine whether a solar battery storage system will be effective for meeting the electrical needs of your household. The following articles offer additional information to help you in your early planning