Efficiency of Solar Panel , LED , Battery , Charge Controller

With the help of technology, there have been ongoing attempts to make solar energy more affordable and efficient. The efficiency of a solar light tends to reduce below 80% over a period of time. The light does not stop working at this phase; however, this period is considered the end of lifespan of a solar light. The performance and lifespan of solar lights are usually determined by the quality of the components used in the solar light system such as light source, battery, controller, panels and other parts connecting all these together.

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Solar Panel Efficiency:

The efficiency of a solar panel refers to the ability of the panel to convert sunlight into usable energy. Higher the efficiency, lesser the number of solar panels you will require to generate the needed electricity.

This type of solar panels is made of the highest purity silicon and they are the most efficient. They can convert a quarter of the sunlight they get into electricity.

This type of solar panels is able to give out their best performance even in high temperatures and they are also less expensive than monocrystalline panels.

Factors Affecting Solar Panel Efficiency:

  • Shade

Solar panel should be positioned in a clear area with no shade. If there is a shaded area, the efficiency of the panels will be reduced.

Install the solar panel in the position which gives more hours of sun exposure to the panel to increase the effectiveness.

Solar panels typically have a lifespan of around 25 to 30 years. The efficiency of the solar panels decreases a little bit overtime.

Cleaning the solar panels regularly is important since dust or dirt can accumulate on the surface. This may block some of the sunlight and reduce the efficiency of the panels.

LED Efficiency:

The efficiency of a light bulb is measured in lumens per watt. LED lights virtually produce no heat (limited to 80%) in the illuminating process, therefore they are relatively cool. Approximately 20% electric energy gets transformed to light energy in these bulbs.

While in traditional bulbs, about 80% electric energy is lost as heat energy resulting on only 20% efficiency, that is, conversion to light energy. The most efficient commercially available LED lamps have efficiencies of 200 lumens per watt.

Battery Efficiency:

Efficiency of solar batteries refers to how much energy is successfully stored and converted to usable electricity. The efficiency depends on a number of factors including the rate of charging or discharging. Higher the rate of charge or discharge lower the efficiency.

  • The Lead Acid battery is not 100% efficient at storing electricity - you will never get out as much as you put in when charging. Overall, an efficiency level of 85% is often assumed.
  • Lithium Ion (Li-ion) batteries are highly efficient. Li-ion has 99% charge efficiency, and the discharge loss is small.
  • The average efficiency of Lithium Iron Phosphate (LiFePO4) battery is 92% and the battery does not need to be fully charged.

While traditional solar street light are supported by lead acid batteries, modern solar street lights prefer lithium-ion or LiFePO4 batteries.

Charge Controller Efficiency:

A solar charge controller is an electronic component that controls the amount of charge entering and exiting the battery and regulates the optimum and most efficient performance of the battery.


The main purpose of the controller is to prevent the batteries from over charging. There are 2 types of charge controllers:

  • PWM (Pulse Width Modulation) Charge Controller

PWM controllers have the more basic charging feature. They mainly just drop the voltage coming from the solar panel to charge the batteries. This drop in voltage equates to a loss in wattage, causing 75-80% efficiency.

  • MPPT (Maximum Power Point Tracking) Charge Controller

MPPT charge controller finds out at any given condition what the maximum operating point for the solar panel’s current and voltage is. With this method, MPPT controllers are actually 94-99% efficient.

Efficiency and reliability of a solar light system also depend on the exterior design of the unit. The components used to support a solar light are expensive and should be protected from any physical damages. Therefore, the lights are housed inside a casing made out of ABS and metal alloy material and are also weatherproofed and waterproofed. It is always preferable to purchase your solar lights from a well-known manufacturer and dealer for good quality components.

Routine maintenance can also reinforce the efficiency of the components. Along with cleaning the panels and checking if anything is blocking sunlight from striking the panels which is affecting the brightness of the LED, you may also inspect the connections and look for battery corrosion. With routine inspection and servicing, the performance and efficiency of the solar lights can be supported in order to extend the overall life of the components.