An application note from Microchip: Practical guide to implementing Solar Panel MPPT Algorithms (PDF!)
This application note describes how to implement MPPT using the most popular switching power supply topologies. There are many published works on this topic, but only a tiny portion of them show how to actually implement the algorithms in hardware, as well as state common problems and pitfalls. Even when using the simplest MPPT algorithm with a well-designed synchronous switching power supply, it can be expected that at least 90% of the panel’s available power will end up in the battery, so the benefits are obvious.
Practical guide to implementing Solar Panel MPPT Algorithms - [Link]
The following is important because with flexible organic photovoltaic cells, we are nearing a new era of development for practical solar-based solutions can be implemented with clever usage of these devices. Efficiency needs to be higher, but technology is progressing in the right direction and a breakthrough is inevitable.
Heliatek announced a record breaking 12.0% cell efficiency for its organic solar cells. This world record, established in cooperation with the University of Ulm and TU Dresden, was measured by the accredited testing facility SGS. The measurement campaign at SGS also validated the superior low light and high temperature performances of organic photovoltaics (OPV) compared to traditional solar technologies.
New world record for organic solar technology with a cell efficiency of 12% - [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]
Small photovoltaic modules of the SMH series will reliably solve the power sourcing of low-power devices.
With modern components, it´s no problem to design devices with power consumption in units of mA and less. That´s why already one small solar module combined with a backup battery or a supercapacitor often solves power sourcing of devices intended for usage in places without electric energy, or in places where a connection to electricity would be inadequately expensive.
SMH series belongs to a segment of small solar modules primarily intended to be built-in to target devices – measuring systems, sensors, communication devices, … High quality construction and a high reliability predestine for various industrial devices. Power in a range of 407-1023 mW is sufficient for many applications including various control units (for example with low-power bistable relays).
SMH3, SMH4 and SMH8 are made of monocrystalline silicon with a UV resistant encapsulation of the IP65 class, optimized for outdoor use (polyurethane, 1.8mm overall thickness of module). As already their name says, they consist of 3,4 or 8 cells, what results in an output voltage of 1.65V, 2.2V or 4.4V. Leads are constructed as soldering pads on a rear side of modules. All modules are 100% electrically and optically tested. Color of modules is dark blue (almost black).
Supply your devices even in the desert - [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]
Don Scansen writes:
For any complete energy-harvesting system designed to provide power to anything but small, short-duration loads, storage batteries represent a necessary but significant portion of the initial expense. The cost of batteries over the lifetime of the system can have an even larger impact if care is not taken to maximize the useful life of the battery component. What’s more, if unit growth continues for photovoltaic and other energy-harvesting systems relying on large-capacity storage batteries, designs that fail to maximize battery life could have a negative environmental impact due to the extra material and energy consumption needed to manufacture replacement systems as well as dispose of exhausted units.
Charge Controller Design for Maximum Battery Lifetime in PV Systems - [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]
Sam Davis writes:
Individual solar-panel systems produce dc power for remote applications while also storing energy in a rechargeable battery supported by a battery-charger IC.
In non-utility grid applications solar panels produce dc power for emergency roadside telephones, navigation buoys, and other remote loads. Virtually all 12-V-system solar panels comprise a series of photovoltaic cells that have a maximum output power of less than 25 W. In producing this power the solar-panel system uses a battery to provide power when the panel is “dark.” The rechargeable battery can supply power for long periods of time, requiring a charger that can properly operate a solar panel.
Meeting this need is Linear Technology’s LT3652 monolithic buck-charger IC, which operates with a single solar panel. The IC uses average-current-mode control-loop architecture to provide constant current/constant voltage (CC/CV) charge characteristics with a programmable charge current. The charger can be programmed to produce a 14.4-V float voltage. Housed in a 3- × 3-mm DFN-12 package, the IC can charge a variety of battery configurations, including up to three Li-Ion/Polymer cells in series, up to four Lithium Iron Phosphate (LiFePO4) cells in series, and sealed lead-acid batteries up to 14.4 V.
Power-Tracking Battery-Charger IC Supports Solar-Power Systems - [Link]
Researchers at the University of Basel in Switzerland say they have developed a new approach to producing environmentally sustainable photovoltaic devices. The research team developed a new method for producing dye substances and attaching them to the surface of titanium dioxide nanoparticles. With this they demonstrated that simple dye compounds based on zinc, a readily available metal, can be used.
Dye-sensitized solar cells (DSCs) consist of titanium dioxide, a semiconductor material coated with a colored dye. The dye absorbs sunlight and injects electrons into the titanium dioxide, which ultimately results in a photovoltaic current. Conventional DSCs use ruthenium dyes, but ruthenium is very rare and expensive. The research team showed that dyes made with abundant and relatively inexpensive copper are effective in DSCs, and that low-cost zinc compounds can also be used. Although the new devices are not yet especially efficient, the finding opens the way to new generations of DSCs with previously ignored dye types. [via]
Dye-sensitized Solar Cells based on Zinc Compounds - [Link]