Solar-based HBLED lighting solutions

Over the past fifteen years, energy demand has increased tenfold, and energy costs have risen fourfold. Blackouts and brownouts have already occurred in the United States and other countries, and will continue to worsen as energy demand grows and energy production cannot be maintained. According to the latest report from the North American Electric Reliability Corp, electricity demand in the United States alone is expected to grow by 141,000 megawatts in the next decade, while only 57,000 megawatts of new resources have been confirmed during the same period. This creates a gap of 84,000 megawatts, equivalent to the total power generation of 160 large power plants.

According to the U.S. Energy Information Administration, electricity generation (mostly to power lighting applications) produces 37% of greenhouse gases, so we should start looking for alternative energy sources such as solar energy. Solar energy is a green technology and does not cost as much as hydroelectric, geothermal or nuclear power generation.

In the 21st century, up to 300 million households in developing countries will lack adequate lighting.

The reasons may vary, but they may include affordability (too high a cost), lack of infrastructure, and imbalance between supply and demand. Many families use homemade kerosene lamps.

Or candles for lighting. These dim, dirty, smoky light sources are very harmful and not environmentally friendly. In the long run, they are more expensive than bright, white, solar-powered high-brightness light-emitting diode (HBLED) light sources.

Why choose HBLED for lighting

Longer lifespan

LEDs last longer than any other light source, with a lifespan of more than a decade in many applications. They contain solid-state technology similar to that used in the latest microprocessors, with no moving parts, no fragile glass environments, no mercury, no hazardous gases, and no filaments. There is nothing that can break, crack, shatter, leak, or contaminate. Unlike typical traditional light sources, LEDs will not suddenly fail or burn out. LED light sources will not suddenly stop working at any time, but LED performance will gradually decline over time. It is predicted that most LEDs will still have an average brightness of 70% of their initial brightness after 50,000 hours of operation. For example, in an application environment where the light source is used 12 hours a day, 365 days a year, a system that has been in use for more than eleven years will only have a 30% decrease in initial brightness output (70% lumen maintenance rate).

Table 1 Comparative analysis of light sources

Figure 1 LED lighting development map

Reduce maintenance costs

Because LED-based light sources last ten times longer than conventional light sources and do not require frequent replacement, routine maintenance costs and periodic replacement expenses are reduced or even eliminated. This is especially important in critical, modulated lighting applications such as buoys, beacons, emergency exit lighting, backup lighting and security lighting, which typically require regular bulb replacement.

More energy efficient

LED light sources are more efficient than incandescent lamps and most halogen lamps. White LEDs can provide more than 20 LUs per watt and are expected to reach more than 50 LUs per watt in the future. When choosing solid-state lighting as an alternative lighting, the overall advantages at the system level must be considered. For example, due to the superior luminous flux performance per watt, LEDs used in building lighting systems consume less energy per hour than competing light sources, making them more environmentally friendly and cost-effective.

Advantages of LED

• Reliable (100,000 hours) — reduced maintenance costs
• More energy efficient - a green, cost-effective solution
• Instant on and fully dimmable with no color shift—Pulse Width Modulation (PWM) control
• Mercury-free - complies with environmental regulations
• Low voltage DC operation—no high voltage connection required

How Solar-Powered LED Lighting Works

FIG. 2 is a block diagram illustrating a solar-based LED lighting implementation.

Figure 2 Solar-based LED lighting

The solar panel converts solar energy into voltage, which is then stored in the battery. Freescale's 8-bit HCS08QG4/8 microcontroller (MCU) with a two-channel, 16-bit timer is used for battery charging and monitoring, driving the LED. PWM is used for battery charging, and the analog-to-digital converter (ADC) is used to monitor the battery voltage. If the voltage drops below 50% of full charge, the brightness of the LED is automatically reduced to 50% by changing the duty cycle of the spare PWM channel. The purpose is to provide longer duration lighting, even with reduced brightness. If the battery voltage drops to 10%, the MCU will turn off the LED to ensure that the battery is not completely drained.

Choosing the Right Microcontroller

There are several options when choosing an MCU for solar-powered LED applications. The HCS08QG4/8 devices offer an excellent combination of required features at a very competitive price.

The MC9S08QG8/4 extends the advantages of the Freescale HCS08 core to low pin count, small package options. The QG device is a low voltage device with on-chip in-circuit flash programmable down to 1.8V. It includes all the standard features of the HCS08 MCU, such as wait modes, multiple stop modes, powerful emulation capabilities, a full set of serial modules, temperature sensors and powerful memory options.

Table 2 Characteristics of MC9S08QG8/4

16-pin DIP/TSSOP/QFN

application

Solar-powered HBLED lighting can be used for street lighting, home lighting, emergency lighting and rural lighting.

Traffic lights are on day and night in most cities, and street lighting is on for most of the day. Solutions that use HBLED technology to replace traditional halogen lamps or energy-saving lamps (CFL) can achieve huge savings in energy consumption and maintenance costs.

The International Finance Corporation (IFC), the private sector investment arm of the World Bank Group's Lighting the Land of Pyramids project, plans to sell solar-powered LED lighting systems to the 1.6 billion people around the world who are not connected to the power grid. Due to the lack of electrical lighting, many of them and their businesses rely on carbon fuels (such as kerosene) to meet their lighting needs. By using solar and LED lighting in these locations, we can reduce the health hazards and greenhouse gas emissions associated with the burning of fossil fuels.

Final Note on Energy Conservation

In 2006, China was the world's second largest electricity consumer, consuming a total of 2,475 billion kWh of electricity, of which 12% was used for lighting. By 2020, if LED efficiency reaches 150 lm/W, even if only 30% of the Chinese market is penetrated, annual energy savings will reach 200 billion kWh.

in conclusion

LED lighting technology is a far-reaching, measurable, energy and cost-saving alternative lighting solution, providing a low-maintenance solution for a variety of lighting applications. Because it uses much less electricity than many traditional lighting methods, LEDs can also help improve the environment by reducing power generation and its corresponding greenhouse gas emissions.