The internet community quite enjoying the destabilizing effects of global connectivity on the status quo, fights any attempt at restriction tooth and nail. Organizing themselves both on- and offline they managed to stop anti-piracy laws like the Stop Online Piracy Act (SOPA) or the Protect IP Act (PIPA) from passing. But it wouldn’t be the internet community if people weren’t working on technological solutions as well. Hackers, engineers and freedom-loving folk are working to create a decentralized, independent network where you can’t stop the signal. [via]
Build a Solar Powered Wikipedia Server - [Link]
Energy harvesting with a photovoltaic cell requires an efficient dc-dc converter that operates with very low voltage inputs and whose output can charge an external battery. The newly introduced LTC3105 meets these requirements.
Sam Davis writes:
ENERGY HARVESTING CAN EMPLOY SURPLUS OR AMBIENT energy to trickle charge a battery that supplies system power. This eliminates the need to for an ac power line-based recharging circuit, which may be impractical in a remote application. Typically, these applications require very low average power, but can require periodic pulses of higher load current. The Linear Technology LTC3105 is intended for these types of energy harvesting applications.
The LTC3105 is a high efficiency dc-dc boost converter (Fig. 1) that has a 250mVstart-up capability. A resistor divider connected between the VOUT and FB pins adjusts the converter output from 1.5V to 5.25V. An integrated maximum power point controller (MPPC) optimizes performance from photovoltaic (PV) cell inputs. The LT3105’s 3mm × 3mm DFN package (or MSOP-12) and very small external components offer a compact solution for energy harvesting.
LTC3105 DC-DC Boost Converter Harvests Photovoltaic Energy - [Link]
Sergei Bezrukov writes:
This project does not directly involve a microcontroller. However, it is designed with a goal to power a PIC-based device. I used electronics from a garden light unit. This device has a solar cell mounted on the top if the light, an LED, a board with a circuit that turns LED on in the dark, and a battery. The battery block is a set of two AA Nickel Metal Hydride Batteries, the reverse engineered schematics of the control board is shown below. The photo cell has a high resistance in the dark (more that 1Mohm), while its light resistance is only about 150Ohm. This way the transistor, which serves as a key, is closed during the day time and the LED is not powered, allowing the solar cells to charge the battery.
Solar charger for three AAA batteries - [Link]
Researchers at Notre Dame have developed a solar cell that is remarkably easy to assemble because the middle layer can be painted onto a clear electrode. First, they mix t-butanol, water, cadmium sulfide and titanium dioxide for 30 minutes. Next, they mask off a clear electrode with office tape. Once the tape is in place, they spread the mixture onto the electrode and then anneal it with a heat gun. Finally, they sandwich an electrolyte solution between the new electrode and a graphene composite electrode. And then, it’s time for testing under a beam of artificial light.
Painting Solar Cells with Nanoparticle Paste - [Link]
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]
Imagine if the next coat of paint you put on the outside of your home generates electricity from light—electricity that can be used to power the appliances and equipment on the inside.
A team of researchers at the University of Notre Dame has made a major advance toward this vision by creating an inexpensive “solar paint” that uses semiconducting nanoparticles to produce energy.
“We want to do something transformative, to move beyond current silicon-based solar technology,” says Prashant Kamat, John A. Zahm Professor of Science in Chemistry and Biochemistry and an investigator in Notre Dame’s Center for Nano Science and Technology (NDnano), who leads the research.
“By incorporating power-producing nanoparticles, called quantum dots, into a spreadable compound, we’ve made a one-coat solar paint that can be applied to any conductive surface without special equipment.” [via]
Nanoparticle paint generates electricity - [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]
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]