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]
A simple charge controller suitable for wind or solar applications. Uses a TL-084 Op Amp, automotive spotlight relay and a handful of other components. The same circuit could also be used as a low voltage cut off to disconnect your battery before its fully discharged. Suitable for 12 and 24v operation.
The controller uses two trimpots to set a low and high switching voltage. When the applied voltage ( battery ) exceeds the high voltage setting, a relay is turned on. The relay will remain on until the applied voltage drops below the low voltage setting.
Wind or Solar Charge Controller - [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 »
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]
Best viewed at 720p and fullscreen, this is truly spectacular. More from Universe Today: [via]
Newly reprocessed images from NASA’s STEREO-A spacecraft, allow scientists to trace the anatomy of a Coronal Mass Ejection in December 2008 as it moves and changes on its journey from the Sun to the Earth. Using a new technique, heliophysicists can now identify the origin and structure of the material that impacted Earth, and connect the image data directly with measurements at Earth at the time of impact.
The different views from left to right are at different scales. The yellow dot is Venus and the blue dot is Earth. Closer to Earth is a dial showing the solar wind density changes at Lagrangian point L1 where the ACE and Wind spacecraft recorded the event.
NASA Video: Solar Storm Enveloping the Earth - [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]
Ransomhall writes – [via]
Thanks to this nice tutorial http://ladyada.net/make/solarlogger/ I’ve done a substantial upgrade! Now I can monitor and save the following data:
- Voltage: Panel, Battery, Load
- Current: Panel and soon battery (waiting on parts)
- Temperature: battery, in case it gets too hot.
Solar MintyBoost - [Link]
An unconventional, scalable high efficiency 12V solar power system, a battery charge controller with low voltage cutout to protect the battery. www.opend.co.za writes:
Low idling current
This circuit was designed for small to medium lead acid systems and feature a lowish idle current ( 5mA ) which increases battery life on small capacity systems.
Easily obtainable parts
All the parts in this design are through hole parts and can be found from a number of sources. None of the parts need programing and only a voltmeter and an adjustable supply is needed to calibrate the board. This makes it easy and cheap to build and maintain.
This is the 3rd iteration of the design, with improvements and bug fixes at every step.
A Novel high efficiency scalable solar regulator - [Link]