As the name suggests, a solar charge controller is a device that regulates current so that the batteries can be protected from over charging. Its main role is to regulate the current and voltage from the solar panels going to the battery. Solar charge controller price is dependent on the type of controller you go for.
Role of a Solar Charge Controller
- Think of it as a regulator. Its role is to deliver power from the PV array to system loads and then the battery bank. It will taper off the charging current when the battery bank will be nearly full. This is done to maintain the voltage to fully charge the battery. By doing this a solar charge controller protects the battery. It is believed that batteries are the most expensive part of the solar system. So, a controller protects it from undercharging or overcharging.
- The advanced charge controller can monitor the temperature of the battery and adjust them to optimize the charging accordingly. This phenomenon is known as temperature compensation.
- It is true that if you run batteries in the partial state of charge, then they can get damaged. It can cause the plates of these lead-acid batteries to become sulfated and also reduce the lifespan of the batteries. If the batteries are overcharged then it can cause excessive gassing which further spoils the plates of the battery. High pressure and overcharging can also cause the batteries to explode in extreme cases. To avoid this issue, small charge controllers come with a load control circuit whereas, in the case of large controllers, separate load control switches are attached.
- Some controllers also come with remote data monitoring. If compatible communication equipment is attached to the controller, then you can monitor them locally.
Type of Charge Controller
There are two types of the solar charge controllers. One is PWM and one is MPPT solar charge controller. Solar charge controller price is also dependent upon which type you go for, PWM or MPPT.
PWM- Pulse Width Modulation-
It is a simple controller that uses a switch between the PV array and the battery. When the batteries become full, PWM uses the switch to open or close rapidly so that the electricity coming from a solar panel can be pushed back. This helps to taper off the charge current when the batteries become full. With PWM normal voltage solar panels are used. In the case of PWM, the array voltage is equal to the battery voltage as the controllers operate using a switch only.
A PWM is a good choice in case a long wire run and nominal voltage solar modules are used. PWM is also used in areas that get direct and constant sunlight like tropical areas and deserts. These units are also used where the requirement is of smaller units. The PWM technology is also cost-sensitive and can be used when added cost with MPPT technology is not worth it.
MPPT- Maximum Power Point Tracking
These controllers are more sophisticated. They can easily adjust the input voltage and the current of the PV array in order to find the optimum operating voltage. During bulk charging, an MPPT controller is able to generate more power than a PWM. This is the reason, MPPT is costlier than PWM. These controllers can be used with PV arrays that have a higher voltage. This way you can use different solar PV panels which will cost you less. MPPT controllers are more desirable in places where the sunshine is variable; the temperature fluctuates, in southern or northern latitudes which get heavy snowfall during winters. MPPT technology has the power to generate maximum output even during challenging conditions.
Factors to Look for in a Charge Controller Before Buying One
It is very important to choose the right charge controller depending upon its features and size. Lower cost controllers might not be as reliable and may not even meet the vital charging requirements. On the other hand, poor performance or reliability can cost more as it involves repetitive expenditure on replacement of the battery, loss of operating time, or site visits, etc. A good solar charge controller is designed in such a way that it can deal with a lot of heating and can manage it properly.
Small charge controllers have fans installed that can get rid of the heat by simple passive cooling. The fan can be eliminated to get the following advantages-
- Greater Efficiency- Since the fan needs electricity to run; this electricity is derived from the solar panels. If the fan is eliminated, this electricity can be used somewhere else. Hence, providing more efficiency.
- Longer Life- Fans pull in a lot of dust, dirt, and small insects which can get clog the controller and shorten its life.
- Higher Reliability- the fan is the only moving component in a controller. If this fan is eliminated, the controller becomes more reliable.
Small charge controllers also come with preset settings. If you feel that the battery requirements don’t meet these preset settings, then you can choose a controller with more advanced setting options.
Large charge controllers use passive cooling but they don’t have fans. They incorporate advanced thermal-mechanical software and design. Large controllers are used in installations where replacements are difficult and maintenance is infrequent.
It is important for you to know that the solar charge controller price based on the MPPT technology is higher than the one based on PWM technology but that doesn’t mean MPPT is better than PWM. You have to decide between these two technologies depending upon your location and application. If the solar charge controllers are properly sized, then both kinds can keep the batteries charged. A solar charge controller is the heart as well as the brain of the solar panel system. It gives your battery a longer life, maintains battery health in difficult conditions, offers the flexibility of controlling load, and has system monitoring functions also. You can go through the options available in the market and choose the best one so that you don’t have to incur additional costs later on.