High brightness LEDs and special optics allow street lamps to be spaced up to 50 meters apart — much wider than is possible with other solutions. By charging these street lamps efficiently during daylight hours using solar energy, the capacity of the conventional electricity grid can be supplemented, saving money and reducing CO2 emissions. This solution dubbed Solar Gen2 and developed by NXP Semiconductors in collaboration with Philips Lighting has resulted in the most cost-effective solution per km of road lighting and provides a serious alternative to grid-connected AC systems.
NXP’s MPT61x range of intelligent charge controllers for maximum power point tracking (MPPT) make it possible to transfer the maximum amount of power from the solar panels to the batteries, achieving up to 98% power conversion efficiency with solar photovoltaic (PV) cells. The controller that includes an ARM7TDMI-S MCU core running at 70 MHz features intelligent algorithms for battery charging and discharging to maximize battery life and it is also capable of dimming light levels as needed based on self-learning and a history log. [via]
Self-learning solar-powered LED street lights save energy - [Link]
Solar PV Monitoring System / OpenEnergyMonitor. Glyn writes – [via]
Here is the documentation for a solar PV monitoring system that’s been developed as part of the OpenEnergyMonitor project. It’s based on Arduino and is fully open-source; hardware, firmware and web application.
The system monitors both generation and consumption and gives the user a clear indication of when their household electricity demands are being met by their solar PV array (green light) or when their not (red light). The wireless display also shows how much electricity is currently being exported or imported. Monitoring data is also posted on-line by a wireless web-connected base-station to our powerful open-source web-application emoncms.
This development is part of the actively on-going OpenEnergyMonitor project to design and build open-source tools for the monitoring, visualization and control of energy.
Open-source solar PV monitoring system - [Link]
Jon Gabay writes:
Renewable energy can be an expensive endeavor and photovoltaic systems are no exception. Ground and roof-mount frames have to be tough enough to handle weather extremes and conditions, and can be very costly even without tracking.
If you use storage batteries, there are large initial expense and the replacement costs every so many years to be considered. On the positive side, 90 percent of the materials in a lead acid battery are completely recyclable. Chargers and inverters are not cheap either.
The panels are the biggest expense. Fortunately, with higher manufacturing capacities coming on line, photovoltaic panel pricing is starting to come down, but not yet to the level of mass deployment.
In 2008, the price of $1000/kg of silicon kept panels at process of three to four dollars per watt. Combining the increase in silicon production capacity with the global slowdown has dropped the price to the $40/kg level meaning we may soon really be at the coveted one dollar per watt price point that many say will make photovoltaic solar on a level playing field with non-renewable energy technologies. We are presently around $1.50 per watt.
To get to that level of high deployment, payback has to be quicker. The lower cost promise of solar panels is one factor for quicker return on investment. The other is the changed architecture of photovoltaic systems stemming from the use of micro inverters.
Either way, the market for the electronics that make use of the solar energy more efficiently is about to explode.
Squeezing Energy from Photovoltaic Panels - [Link]
Research at Lawrence Berkeley National Laboratory (Berkeley Lab) has led to solar cells with record-breaking efficiency. Contrary to conventional scientific wisdom, it turns out that efficient solar cell materials are characterised by high photon emission instead of high photon absorption.
According to the researchers, external fluorescence is the key to approaching the theoretical maximum efficiency for conversion of sunlight into electricity. The maximum efficiency, called the Shockley-Queisser (S-Q) efficiency limit, is approximately 33.5% for a single p-n junction. An analysis by a member of the research team indicated that gallium arsenide is capable of approaching the SQ limit. Based on this work, Alta Devices Inc., a private company spun off by the researchers, has fabricate gallium arsenide solar cells that achieved a record conversion efficiency of 28.4%. [via]
Researchers find key to better solar cell efficiency - [Link]
As renewable energy is becoming integrated into our everyday lives, new terms such as solar panel, photovoltaic and solar cell are more common and new devices, such as outdoor LED lighting are using this technology. The sun emits many forms of radiation. The best way to describe this is that there are ‘waves’ of energy that radiate from the sun at different frequencies.
This is only partially the truth as there is both a wave and particle nature to light.
The light spectrum is divided into different sections. It begins with the highest, gamma rays and ends with the lowest, long wave radio. Only a small portion of this is visible, called the visible spectrum and this occurs towards the middle of the range which lies between Ultraviolet and Infrared frequencies. Ultraviolet radiation is what burns the skin and can cause skin cancer. It is blocked by most types of glass and is partially reduced by the atmosphere especially the ozone layer. Infrared radiation is what provides the earth with heat and it is that which is trapped by green house gasses, carbon dioxide mainly and is causing global warming.
Infrared radiation is targeted by solar panels. This basically uses the energy generated by the radiation to heat water in pipes that flows and generates electricity. This can be used to charge a battery which could then power said LED lighting. As mentioned previously there is a dual nature to light. It consists of both a particle and a wave. It might help to think of the particles moving in a wave like pattern but the reality is more complex than that. The important thing to remember is that the light particle, the photon, is what is targeted by a solar cell. Read the rest of this entry »
Daniel F. Butay & Michael T. Miller writes:
The design and implementation of a Maximum Peak Power Tracking system for a photovoltaic array using boost DC-DC converter topology is proposed. Using a closed-loop microprocessor control system, voltage and current are continuously monitored to determine the instantaneous power. Based on the power level calculated, an output pulse width modulation signal is used to continuously adjust the duty cycle of the converter to extract maximum power. Using a Thevenin power source as well as a solar panel simulator, system design testing confirms simulation of expected results and theoretical operation is obtained.
Maximum Peak Power Tracker - [Link]
For the last year I’ve been working on a prototype for a Solar Inverter that can be Grid Intertied. A solar inverter takes the 12V DC (or other voltages) from the solar panels and converts it to 120V AC which is the power that most of your household appliances use. A Grid-Intertied inverter allows you to feed that power back into power grid (your house power) to help power your household appliances.
My goal was to design a small inverter, about 100W, that could be used with one solar panel and could be grid intertied. My second prototype (pictured above) has achieved these design goals. So on these web pages I’m going to document the design of the hardware and the software of my solar inverter. I’m releasing these designs to public without restrictions. All I ask is that if you use any of my design that you credit me and add a link back to this website. I hope these designs will help further the work of other people in this area.
Solar Grid-Intertie Inverter - [Link]
To understand why the PPT can increase the efficiency of your solar power charging system a closer at the electrical characteristics of a solar panel is necessary. Solar panels convert photons from the sun striking their surfaces into electricity of a characteristic voltage and current. The solar panel’s electrical output can be plotted on a graph of voltage vs. current: an IV curve. I represents the current in amps and V represents the voltage in volts. The resulting line on the graph shows the current output of the panel for each voltage at a specific light level and temperature. (Fig. 2) The current is constant until reaching the higher voltages, when it falls off rapidly. This IV curve is applicable to the electrical output of all solar panels.
Arduino Peak Power Tracker Solar Charger - [Link]
Solar chargers use solar energy to power my electronics, neat! How do they work?
Short answer: Sunlight hits solar panels -> solar panels generate electricity -> electricity flows into battery -> battery outputs clean power on demand to your device
Long answer: We’ve created a five part tutorial to take you through every stage of the process. Solar is obviously much less predictable than plugging into the grid so we’ll be focusing both on specifications and what to expect in the real world. Bring along a multimeter and some parts from Radio Shack and you can get a pretty good idea of how exactly how solar charger work.
Solar Charger Tutorial - [Link]