Researchers at Stanford University claim to have developed the world’s first peel-and-stick thin-film solar cells (TFSCs) that don’t require any modification of existing processes or materials. The new process would allow the creation of decal-like solar panels that could be applied to virtually any surface.
Unlike with standard thin-film solar cells, the new process doesn’t require direct fabrication on a final carrier substrate. Instead, a 300-nm film of nickel (Ni) is deposited on a silicon/silicon dioxide (Si/SiO2) wafer, on which thin-film solar cells are then deposited using standard fabrication techniques, and covered with a layer of protective polymer. A thermal release tape is then attached to the top of the thin-film solar cells as a temporary transfer holder. [via]
Peel-and-stick solar cells - [Link]
This teardown article will delve into the architectural design and components of a solar inverter card starting from the Solar panel DC inputs and working our way through the DC to AC conversion process to the AC output that is sent out to the power grid. We will show what features need to be implemented into such a design to meet various safety and other performance standards as well as stringent power company demands upon the signal that is put onto their grid.
Teardown: The power inverter – from sunlight to power grid - [Link]
By Lee H. Goldberg:
The Schottky bypass diodes used in most cell-based solar panels serve as a protection mechanism that allows the panel to continue producing power when one of its cell strings is shaded or damaged. However, the characteristics of traditional diodes create energy losses that reduce the overall efficiency of a solar power system and, in some situations, may actually cause costly damage. To solve this problem, several manufacturers have introduced a new class of “active diodes” that use transistors to produce diode-like behavior, while allowing the solar panels they protect to operate with higher efficiency and better reliability. This article will explore the technology that underlies active diodes, look at the products currently on the market, and look at how they are changing the way solar panels are being designed and manufactured.
Active Bypass Diodes Improve Solar Panel Efficiency and Performance - [Link]
MIT engineers have proposed a new way to improve solar cell performance by using special ‘funnels’ to capture photons. The funnels would be formed in a thin film of semiconductor material by pressure from microscopic needles, producing elastic strain in the funnel area. The strain causes the band gap of the material to vary over the surface of the funnel, which allows a broader spectrum of light to be converted into electricity. The electron/hole pairs produced by the photons in the incident light would also be guided toward the centre of each funnel by electrical forces, improving efficiency compared to the usual diffusion process.
The MIT team used computer modelling to determine the effects of elastic strain on a funnel depression in a thin sheet of molybdenum disulphide (MoS2), a natural semiconductor material that can form films just one molecule thick. The elastic strain, and the corresponding change in the potential energy of the electrons, varies with the distance from the centre of the funnel. The potential energy determines the wavelength of the photons that can be captured by the material, and thus the portion of the light spectrum that can be converted into electricity. The team hopes to carry out laboratory experiments in the future to confirm their theoretical findings. [via]
Energy Funnels Boost Solar Cell Performance - [Link]
This document covers a few of the applications where lasers can be used during the fabrication of crystalline silicon
(c-Si) solar cells.
Manufacturing c-Si Solar Cells with Lasers - [Link]
We all know, we should use more renewable energy. Here is my contribution. Use solar power if you want to cut 20mm wooden rods. And plan ahead because it may take a while.
The Almost Useless Machine - [Link]
Chris Glaser writes:
Many solar-panel-powered applications need only pulses of power to operate. Systems for data collection or measurement sampling frequently need to turn on, perform a measurement or some other task, transmit the processed or measured data, and return to sleep. In many cases, wirelessly transmitting the data consumes the largest portion of output power. These required power pulses, either for the system itself or for transmitting data, typically are difficult to support with a power-limited supply such as a solar panel. By operating at the solar panel’s maximum power point (MPP) and by intelligently drawing the power from the panel, energy can be successfully harnessed to power a pulsed load. This article presents a simple and costeffective solution for maximum-power-point tracking (MPPT) for use in such pulsed-load systems.
Easy solar-panel maximum-power-point tracking for pulsed-load applications - [Link]
The Raspberry Pi solar data logger project is now live and is the latest version of our previous data logging systems using Arduino and Android + IOIO board projects.
The data is used on a custom reporting website onhome.briandorey.com and also on Android and iPad tablet apps.
The Raspberry Pi is used as a data processing and uploading system which pulls data from the following sensors and then uploads to a web server via HTTP GET.
Pi Solar Data Logger - [Link]
Electrical engineers of the University of Princeton are working on a cheap solar-powered charging system that can be printed on plastic and that transfers the produced electricity wirelessly. The solar cells are made from amorphous silicon (a-Si), a non-crystalline form of silicon. Crystalline silicon (c-Si) is much more efficient when it comes to converting sunlight into electricity but a-Si has the advantage that it can be processed at much lower temperatures (75 °C against 300 °C for c-Si), allowing it to be printed on plastic sheets.
The electric circuit is made out of the same material as the solar cells. And although a-Si has a lower electrical performance than c-Si, when it comes to producing cheap electricity-generating plastic sheet which can be put up anywhere, a-Si is best. By making the charging system available at a large scale, the Princeton engineers aim to have wireless electricity everywhere. [via]
Omnipresent Sun-Powered Wireless Charging Stations - [Link]
SolarCharge 200ds230 rev 2 – An unconventional, scalable high efficiency 12V solar power system, a battery charge controller with low voltage cutout to protect the battery. [via]
An unconventional, scalable high efficiency 12V solar power system and battery charge controller with low voltage cutout to protect the battery. (ideal for systems of 50W or less).
The most common solar charger consists of a Schottky diode to prevent the battery from draining into the PV panel and a shunt regulator that effectively short circuits the panel once the battery is fully charged.
One problem with this approach is diode losses and the resulting heat. If a 50W 12V panel supplies 4A to the battery, the Schottky diode will drop about 0,4V across it dissipating about 1,6W of heat. This requires a heat sink and loses power to heat. The problem is that there is no way of reducing the volt drop, paralleling diodes may share current, but the 0,4V will still be there. The circuit uses a MOSFET in stead of the usual diode and the primary power loss is resistive.
Scalable 12V solar power system and battery charge controller - [Link]