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]
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]
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]
Arup Basak writes: [via]
O.S.S.D.A.S v1 stands for Open Source Solar Data Acquisition System. I have been working on this project since last few months. The picture above is the not the first prototype, but the first working prototype that looks like quite complete. There will be further revisions to the hardware and software for best efficiency and accurate results. Moreover, the recorded digital data should be rich enough to reflect the real world data’s mirror.
- Logs everything into attached SD card for data analysis in PC. A typical 1GB SD card can store years of data. Data is recorded in frequency of few seconds. Enough to plot a graph to analyze performance of short periods of ten minutes too.
- Keep track of the solar panel voltage, battery voltage, charge current and other parameters
- Keeps track of other data such as temperature, etc
- Can work without the LCD and still record information to the SD card and vice versa.
Open Source Solar Data Acquisition System - [Link]
Steve Taranovich writes:
Home energy systems based on renewable sources, such as solar and wind power, are becoming more popular among consumers and will gain increasing support from governmental bodies.
In this article, the power inverter will be discussed in the context of solar energy, especially as it relates to the latest, low power microinverter architectures that make the most sense in converting a photovoltaic (PV) panel’s DC output to an AC signal for residential use.
Microinverters are installed on each individual PV panel and typically handle 300 W. Microinverters provide the benefit of scalability for those who want to start small, yet have full DC/AC conversion with maximum power point tracking (MPPT). Many people want to put their excess power back onto the power grid, which will speed up the return on investment (ROI) time and ultimately could lead to freedom from grid reliance. The technology that will enable ubiquitous architectures like this on our roof is getting closer.
An Engineer’s Guide to Power Inverters for Solar Energy Harvesting - [Link]
SolarWorld solar modules excel in efficiency and moreover the producer provides an above-standard guarantee of performance.
Company SolarWorld AG Group is a top German producer of solar (photovoltaic) panels. From the raw silicon, through silicon wafers, to the complete modules, SolarWorld produces all this on its automated production lines with a stringent quality control. Sorting of modules ensures, that only modules meeting a declared performance are dispatched for sale. A big advantage is the 25-year linear power guarantee – SolarWorld guarantees max. 0.7% degradation of the module performance p.a. for over 25 years. It is a considerable difference in comparison to a standard 2-stage guarantee, as you can see in the enclosed picture.
SW80 modules use polycrystaline high efficiency cells. High performance of modules was confirmed also in independent tests, where SolarWorld modules provided 10-12% higher performance. Currently, we offer you SW80 modules for a special price, directly from our stock.
Top quality solar panels with a 25-years performance guarantee - [Link]
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]
The SM72441 is a programmable MPPT controller capable of controlling four PWM gate drive signals for a 4-switch buck-boost converter. Along with SM72295 (Photovoltaic Full Bridge Driver) it creates a solution for an MPPT configured DC-DC converter with efficiencies up to 98.5%. Integrated into the chip is an 8-channel, 12 bit A/D converter used to sense input and output voltage and current, as well as board configuration. Externally programmable values include maximum output voltage and current as well as different settings on slew rate, and soft-start.
Programmable Maximum Power Point Tracking Controller for Photovoltaic Solar Panels - [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]
When you expose the silicon die of a transistor to a light source a charge is produced. CircuitsDIY opened up a 2N3055 transistor and did some experimenting. With the help of a magnifying glass he was able to built up a charge of 0.65V and produce 42.2mA of current. [via]
Most photovoltaic cells are made of silicon chip above which there resides a very thin layer of noble metal through which around 1% of photon particles enter the material and activates electron flow. Here I’m showing how to make one simple solar panel using transistor.
Testing the photovoltaic effect with a transistor - [Link]