Grey finish with rechargeable batteries. Bring light to your dark shed, without having to connect to your local power grid. This LED shed light features 10 bright LED's that are powered via a solar panel. The panel can be placed in direct sunshine with the included 20-foot extension cord. Mount the light on the ceiling or wall for maximum flexibility, or use it as a utility light for a work bench. A pull chain allows easy on and off. A switch on the body lets you select between 10 LED's that last 2 hours, or 5 LED's that last 4 hours. The LED's have an average rated life of 100,000 hours, ensuring years of continuous use. The solar panel has a glass cover for protection in wet locations. Includes three AA rechargeable batteries and all mounting hardware. Approved for damp location use as defined by the National Electric Code. Please consult your local electrical code for details. DL # 274093.
Product Details
Lighting
Brand: Designers Edge
Model: L-949
Number of items: 1
Dimensions: .0" h x .0" w x .0" l,
Features
Super bright 100,000 hour LEDs
Glass protected multi crystal solar panel designed for outdoor applications
20-Foot Extension cord allows solar panel to be placed in direct sunlight
Features two power settings
Can be wall or pole mounted up to 20 feet away from fixture
Editorial Reviews
From the Manufacturer
This 10-LED rechargeable solar panel shed light offers 100,000 hours of light. It is ideal for the home, garage, or workplace to automatically and easily illuminate any area to ensure safety and security, all while utilizing solar power. Comes complete with 3 AA rechargeable batteries.
Solar panels use light energy (photons) from the sun to generate electricity through the photovoltaic effect. The structural (load carrying) member of a module can either be the top layer or the back layer. The majority of modules use wafer-based crystalline silicon cells or thin-filmcells based on cadmium telluride or silicon. The conducting wires that take the current off the panels may contain silver, copper or other conductive (but generally not magnetic) transition metals.
The cells must be connected electrically to one another and to the rest of the system. Cells must also be protected from mechanical damage and moisture. Most solar panels are rigid, but semi-flexible ones are available, based on thin-film cells.
Electrical connections are made in series to achieve a desired output voltage and/or in parallel to provide a desired current capability.
Separate diodes may be needed to avoid reverse currents, in case of partial or total shading, and at night. The p-n junctions of mono-crystalline silicon cells may have adequate reverse current characteristics that these are not necessary. Reverse currents waste power and can also lead to overheating of shaded cells. Solar cells become less efficient at higher temperatures and installers try to provide good ventilation behind solar panels.
Some recent solar panel designs include concentrators in which light is focused by lenses or mirrors onto an array of smaller cells. This enables the use of cells with a high cost per unit area (such as gallium arsenide) in a cost-effective way.
Depending on construction, photovoltaic panels can produce electricity from a range of frequencies of light, but usually cannot cover the entire solar range (specifically, ultraviolet, infrared and low or diffused light). Hence much of the incident sunlight energy is wasted by solar panels, and they can give far higher efficiencies if illuminated with monochromatic light. Therefore another design concept is to split the light into different wavelength ranges and direct the beams onto different cells . The use of infrared photovoltaic cells has also been proposed to increase efficiencies, and perhaps produce power at night. Sunlight conversion rates (solar panel efficiencies) can vary from 5-18% in commercial products, typically lower than the efficiencies of their cells in isolation. Panels with conversion rates around 18% are in development incorporating innovations such as power generation on the front and back sides. The Energy Density of a solar panel is the efficiency described in terms of peak power output per unit of surface area, commonly expressed in units of Watts per square foot (W/ft2). The most efficient mass-produced solar panels have energy density values of greater than 13 W/ft2.
Solar Hot Water Heaters < a cost of effective way to generate hot water for your home. They can be used in any climate and uses free energy--the sun! We offer everything needed for the Solar Hot Water Heater systems from solar water storage tanks and controllers to the evacuated tubes and flat plate collectors.
Silicon Solar Inc is the home of the SunMax evacuated solar tube collectors. Evacuated tubes feature parallel rows of transparent glass tubes. The outer glass tube and the metal absorber tube is attached to a fin that absorbs solar energy but averts radiative heat loss. These collectors are used more frequently for U.S. commercial applications. Commercial applications include laundromats, car washes, military laundry facilities and eating establishments. Offering the latest inevacuated tube technology, we continue to provide the industries most affordable, cost effective and reliable sustainable products.
Flat plate collectors are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or polymer covers. The general use of these collectors are for residential buildings.
Solar hot water Controllers control the switching on and off of the solar pump as a function of the collector and storage temperature.
Most Solar how water heaters need a well-insulated Tank. Tanks have an inlet and outlet, allowing the heated water to enter the tank and exit when needed. Silicon Solar offers the best and most-efficient tanks.
All of Silicon Solar Inc advanced solar heating products offer high quality and customer value. With products designed for both commercial and residential applications, Silicon Solar Inc remains focused in offering the industries leading products and services.
Although the initial cost of a Solar Hot Water Heater is greater than for conventional water heating systems such as electric or gas systems, the life-cycle cost of a solar system is actually 20% lower than a conventional one. This is because the other systems carry the added costs of electricity or gas, where the energy of the sun is free. If you are building a new home and you choose to incorporate a a Solar Hot Water System, your savings can be even more, since the cost of the system can be included in the mortgage.
SRCC Certification:
The SRCC, Solar Rating & Certification Corporation, has determined that SunMaxx Evacuated Tube Solar Collectors are the most efficient, and the highest valued Evacuated Tube Solar Collectors available on the market, beating out the leading national and international competitors.
Solar Radiant Heating Kits:
If you are interested in one of our Pre-Packaged Home Heating Kits, all you have to know is the size of your home and the amount of your heating bill that you want to offset. You can purchase all the major components you will need right here from Silicon Solar. No need to have to work through complicated calculations to determine BTU production or heat loss. These systems are capable of providing the majority of the heat for your home or business that is less than 10-20 years old.
Solar Evacuated Tube Collectors:
Silicon Solar offers SunMax evacuated tube collectors, which are among the highest quality collectors available. These collectors are able to generate heat through the coldest of winters, even under overcast conditions, thanks to superior insulation. They consist of two layers of extremely durable borosilicate glass which maintain a vacuum in between that acts as a superb insulator. If you would like to learn more about the benefits of solar evacuated tubes, feel free to contact a product technician at 1-888-SOLAR-11. They will gladly answer any questions you may have.
Flat Plate Solar Collectors:
Flat Plate Solar Collectors are a glazed collectors which feature a coating which maximizes heat absorption, aluminum framing which can withstand heavy weight and is weather resistant, and interior fiberglass insulation which allows for greater efficiency. The combination the latest energy efficiency technology and a strong heat exposure allow for optimal heat transfer and makes these lights the highest in BTU performance. Our Flat Plate Solar Collectors are customized to suit applications based on the US standard rather than the European or Chinese market. This is done in order to keep your costs down.
Thermosyphon Solar Hot Water:
Our Thermosyphon Solar Hot Water Systems are available in 40 and 80 gallon models. These systems are among the most affordable and easy to install of Solar Hot Water Systems. No matter where you live, these systems are an affordable and cost-effective choice. Thermosyphon Solar Hot Water Systems from Silicon Solar feature our innovative SunMaxx Evacuated Tubes a Solar Hot Water Storage Tank which is mounted directly onto the top of the Solar Collector.
Solar Pool Heaters:
Our selection of Solar Pool Heaters are easy to install, clean, and service. They raise the temperature of your pool 10-15 degrees, which allows you to open your pool earlier in the season and close it later in the season than you might otherwise. These Solar Pool heaters are made from high-density rubber and a durable thermal layer which warms the water in your pool and keeps it warm.
Fafco Solar Water Heaters Hot2O:
We offer Fafco Solar Hot Water Kits for existing electric heaters and for existing gas heaters. These systems are affordable, efficient, and environmentally friendly. They are ideal for climates where ice and snow accumulation are not a factor.
Solar Water Storage Tanks:
Our SunMax Solar Hot Water Storage Tanks are constructed of durable stainless steel. The steel shields the insulation of the tank. These tanks feature two heat exchangers and an automatic temperature control thermostat which keep your stored water at the temperature you prefer.
Solar Water Storage Controllers:
Our Solar Water Storage Controllers are for use with Solar Thermal Systems which consist of evacuated tube collectors and a Solar How Water Storage Tank. These Controllers allow you to regulate the operation of the circulator pump based on collector temperature and storage temperature.
Solar Plate Heat Exchangers:
Solar Plate Heating Exchangers are utilized in processes such as:
·Heating
·Cooling
·Refrigeration
·Hydronic
·Steam processes
·Industrial Processes
There are significant advantages to selecting a brazed plate heat exchanger rather than a traditional one.
Solar Hot Water Accessories:
All of the accessories you may need for your Solar Hot Water System are available right here from Silicon Solar. Among our selection of Solar Hot Water Accessories, you will find Heat Dumps, Expansion Tanks, and a number of other accessories. All of these accessories come complete with a manual and detailed installation instructions.
Solar Hot Water Mounting Hardware:
Have a flat or low-pitched roof and need a Tilt Mount upgrade? Have a US made Extra-Durable Face Frame or Mounting rack you would like to upgrade? Would like to mount your Evacuated Tube Solar Collectors on the ground or a pole and are looking for the mounting hardware to do that? If you can answer 'yes' to any of these questions, or have just about any other mounting hardware requirement for that matter, you will find the hardware you need to install your Solar Hot Water Collectors safely and securely.
Pre-Packaged Solar Hot Water Systems:
If you are looking for a way to save time and money and forgo the hassles often associated with researching, purchasing and installing a home Solar Hot Water System, then our Pre-Packaged SHW Systems are the way to go. These kits are ideal to meet the domestic hot water needs of households of 2-6 people. They include our industry leading SunMax Solar Collectors and are available with your choice of our SunMax Evacuated Tube Collectors or our Flat Plate Solar Collectors.
The purpose of educational solar kits is to provide a hands-on activity that can demonstrate the power of solar energy. The power of solar energy and the solar cells that utilize it resides in the scalability of solar cells. The larger the solar panel, the larger the amount of energy that can be converted into a usable form. No system need go without power with a large enough solar array.
The educational solar kits require little power, however. They are small devices that would typically run on one or two AA batteries, but are instead powered by a solar panel. The benefit of using a solar panel instead of AA batteries is clear. Once the educational solar kits are assembled, they will never need a power supply because the solar panel will be able to provide the power needed by converting sunlight into electricity.
Our selection of Educational Solar Kits includes a Solar Cell Sample Pack, Interconnection Materials for Solar Cells, a Beginner Level Solar Kit, A Solar Cell Information Packet, a DEMOKIT Solar Kit, a Solar House Kit, Scrap Solar Cells, a Solar Circuit Kit, rechargeable AA batteries, and the SolarBreeze Demo Kit.
These are in addition to a range of solar toy kits. These toys include a solar helicopter, an RC Solar Car, a Solar Moon Walker, Solar Racing Crawler, a Solar Worm, a Solar Robot, a Solar Airplane, a "Solabug", a Solar Worm, and a "SolaCar".
SHARP polycrystalline 80W solar kit that can produce 4.67 amps. Kit comes complete with a male D/C plug, mounting bracket and screws, battery clamps, voltage tester, quick connectors, and extra wiring. Ideal for boats, RV, 12v battery charging, pumps, satellite dishes, and many other uses. Easy to install, weatherproof, and allows for connecting multiple panels for more power. Unit has a 25-year warranty.
Product Details
Amazon Sales Rank: #14115 in Automotive
Color: Blue/silver
Brand: Sunforce
Model: 39810
Released on: 2006-01-01
Dimensions: 4.00" h x 26.00" w x 51.00" l,
Features
Advanced polycrystalline design is highly efficient and provides superior power output
Maximum power output: 80 Watts/4.67 Amps
Multiple panels can be connected together for even more power
Easy to install, virtually maintenance-free, and backed by a 25-year warranty
Individual panel size: 21" x 48" x 2"
Editorial Reviews
Amazon.com Product Description The Sunforce 39810 80-Watt High-Efficiency Polycrystalline Solar Panel Module will give you several more reasons to love the sun. It provides the power you need, while helping you save money and protect the environment. This panel is ideal for homes, cabins, remote power, back-up power, and 12-Volt battery charging. This panel comes with compatible wiring, accessories and a voltage tester to help you start producing up to 80 Watts of clean, free power in all weather conditions.
Sunforce panels can be easily added to new or existing systems.
Convenient Power That Helps You Save Money and Protect the Environment The Sunforce 39810 80-Watt High-Efficiency Polycrystalline Solar Panel Module lets you harness the power of the sun, the most powerful and plentiful source of energy available to us. This inexhaustible supply of power is freely available wherever the sun shines, and gives users the freedom to power their homes, cabins, batteries, appliances and electronic equipment far from civilization--or even right in town. Solar power can help cut your energy bills by reducing your dependence on the main electrical grid, and can also provide back-up power during outages. Unlike nuclear and fossil fuels, solar power systems are clean and pollution-free, and they require very little maintenance to operate.
Sunforce Solar Panels are effective in areas of both high and lower sun exposure, making them ideal for use in the United States. View Larger
Flexible Power for New or Existing Systems The Sunforce 39810 80-Watt High-Efficiency Polycrystalline Solar Panel Module is an ideal addition to both new and existing solar power systems. It comes with a voltage tester, wiring and mounting accessories to make installation easy. These solar panels can be used individually, or they can be connected together to boost power output. Sunforce High-Efficiency Polycrystalline Solar Panels must be connected to a compatible charge controller (sold separately). The charge controller prevents the solar panel from overcharging and damaging connected batteries or electrical systems. It also prevents reverse current from sapping your battery strength at night. Sunforce High-Efficiency Polycrystalline Solar Panels can be connected in parallel for 12-Volt systems, or in series for 24- and 32-Volt applications. Please ensure that the components being used in your system are compatible with the individual and total output voltage of your solar panels. About Polycrystalline Solar Power Polycrystalline silicon is a material consisting of thin wafers that are cut from a silicon crystal which has grown in several directions. This advanced surface texturing process provides polycrystalline solar panels with a higher power output than amorphous panels of the same dimensions, and makes them more cost and space-effective. These individual wafers are assembled into panels that are covered by durable, weatherproof tempered glass. Thanks to their efficiency and durability, these solar panels require virtually no maintenance once installed. This solar panel has a maximum power output of 80-Watts/4.67-Amps. Solar panels convert sunlight into an electric current; they do not actually store power. Sunforce Solar Power Panels are primarily used to recharge all types of 12-Volt batteries, including lead-acid automotive batteries, deep-cycle (traction type) batteries, gel-cell batteries, and heavy-duty (stationary type) batteries. When using these solar panels to run appliances on a regular basis, the use of deep-cycle marine batteries is recommended. This type of battery is designed to withstand the frequent charge and discharge cycles associated with solar panel use.
Customer Reviews
Sunforce 50048 60-Watt Solar Charging Kit Most helpful customer reviews 36 of 36 people found the following review helpful. Great panel By Gregory K Took the panel to Death Valley for a few days to charge my trailer battery and while I ran laptop and iPod stereo for hours during the night, it quickly recharged the battery the next morning. Built a solid stand/rack to keep it upright using pvc pipe that's easy to disassemble, secure and lock. At 80 watts, it's just one panel where some 65watt units have 3 panels. 55 of 58 people found the following review helpful. 80 watts of pure power By Arik As my first venture into solar energy this has been a nice panel. I've had it about a month. I paired it with a "Xantrex Technologies 802-1500 XPower Powerpack 1,500-Watt Portable Backup Power System" and a "Sunforce 60032 30 Amp Digital Charge Controller". The panel is 12 volt, 4.6 amps though at this point I'm seeing up to 13.6 volts and 5 amps. I suspect over time as the panel weakens it will be more toward the 12 volt, 4.6 amp. The panel was simple to hook up and came with what was needed. I did go purchase new wire as I needed more distance for where I mounted it. I'm able to charge the battery from dead to full in 2 days. If I were to rotate the panel through the day I feel I could fully charge in 1 day. Nice for backup charging and learning. For any real application you would need a ton of these though. 52 of 55 people found the following review helpful. An excellent bargain for either battery usage or grid tie - great size too By HMMWV QUICK UPDATE: Sunforce is selling obsolete Sharp 12% efficient panels no longer in production at 123W/panel, 2 panels to a kit with a junky inverter and charge controller.. See my review at Sunforce 39126 246-Watt High-Efficiency Polycrystalline Solar Power Kit but choose cautiosly as that product is from 2008 and is now obsolete which makes expansion of your system difficult due to the efficiency change. ---back to the review as it stood originally--- In evaluating solar panels (and systems of many panels) the typical pricepoint is $5.10/watt in high volume production. If you are finding better pricing than that something is wrong. An example may be inefficient panels that use larger panels, causing massive panel size such that it is 4-8 times larger than this panel with the same output. Other inefficiencies to watch out for are caused by voltages that are not useful. You could, for example, have a panel that output 500V at 1/10 A for 50W sold for $250 - looks good financially but very few charge controllers go much over 250 volts (and many dont make 250 volts - some are 12 or 48 volt systems). So that panel is not much use This panel is in the sweet spot - enough power to be useful (80W/3 is a simple approximation for what useful power you can get with a battery all day long - about 25W or so given inefficiences. So theoretically it could support a 25W load 24x7 with an 8 hour day of sun. The last inefficiencies to watch out for are panels that need heavy sun before they produce any output. Some panels produce usable (1-2 amps) output with just ambient scattered light such as a foggy day, while others give near zero output unless the sunlight strikes them head on. This panel design gives output whenever there is light, which is good. More light is always better, but it could be worse. So to sum it up - there are no pitfalls here. It passes all the checks for pricing and performance. We load tested a string of 12 of these for a customer to profile their output to help decide if a rotator would help and it showed that very little gain would come from the expense of an automatic rotation system due to the panel's efficiency at many angles. With 12 panels we produced 1KW for 8 hours with taper up and down on both sides. Best of all this can be used in series strings for grid tie systems or with battery maintainers
These lights cost less than $3.00 each and come with a 2.5v solar panel capable of charging at up to 35mA, a rechargeable 1.2v NiCd cell and a circuit we will use to convert the 1.2v + 1.2v to a 5v output.
The two lights are dismantled and all the parts taken off one of the PC boards.
We will be using both NiCd cells in series and the solar panels are placed in series to charge the cells.
The circuits for these Solar Garden Lights are different, depending the manufacturer, however they all do the same job.
The type we have used consists of an oscillator running at about 50kHz and produces a square wave with a high of 60%.
The driver transistor receiving this waveform takes one end of a 100uH inductor to the 0v rail. The other end is connected to the positive rail.
The resistance of the choke (inductor) is fairly important and the ones we tested had a DC resistance from 1.7 ohms to 4.2 ohms and all produced the same output. An inductor with a resistance of 13 ohms did not work.
When the transistor turns off, the spike produced by the inductor is passed though a high speed diode to charge a 100u electrolytic. The voltage produced by the inductor is actually about 12v - 18v but this spike is absorbed by the electro and its voltage gradually rises.
When it rises above 5.5v, a voltage divider made up of a 1M and 150k, creates a voltage of 650mV across the 150k and this turns on the PNP transistor to shut off the oscillator.
Normally, the detection-line to the oscillator is used to detect when the cells are producing a voltage and this shuts off the LED, as the Garden Light determines it is daylight.
This sense-line detects less than a few millivolts to turn on the LED and about 300mV it turns the LED off. This is a very wide gap and is designed to prevent "Hunting."
If we connect directly to this sense-line we will get a 300mV pulsing output. This is called Hysteresis - a condition where a circuit does not change state until a higher voltage is reached and then does not change back again until the lower voltage is reached.
To reduce this Hysteresis, we have added a PNP transistor. This reduces the Hysteresis by a factor of about 100.
Here IC1 is wired as a medium current inverting line driver, switched by an encapsulated light detector (10mm LDR). Multi-turn trimpot P1 sets the detection sensitivity. When ambient light dims,transistor T1 turns on to drive the white LED string (D1-D8). Now this lamp load at the output of T1 energises. Resistors R1-R8 limits the operating current of the LEDs. When the ambient light level restores, circuit returns to its idle state and light(s) switched off by the circuit.
Solar 5v Supply Circuit Outdoor LED Solar Lights Circuit Schematic form china
The two solar panels, 2 cells and matrix board
with a 1k load resistor. The 1R in series
with the solar cells detects charging current.
Use a multimeter set to mV. Each mV
represent 1mA charging current.
THE CIRCUIT
The circuit is designed around a "flyback Oscillator." This consists of an oscillator running at a high frequency.
The output drives a transistor that is connected to an inductor. An indicator is a coil of wire wound on a metal or ferrite material. It can also be wound with an air core but it will not have the same output in this circuit.
When an inductor is paced across a battery, it will not allow a high current to flow immediately. A small current flows and this produces magnetic flux and the flex cuts the other turns of the winding to produce a voltage in the opposite direction. This voltage opposes the incoming voltage and the result is only a very small voltage. This small voltage only allows a small current to flow.
The magnetic field is constantly increasing and this is called expanding flux and this expanding flux does not produce quite the same amount of reverse voltage in the winding due to the permeability of the magnetic material. So the effective incoming voltage becomes higher and this produces a higher current.
All this is happening in microseconds but eventually the current is a maximum and core is saturated with flux and it cannot produce a higher density of expanding flux. This is the point at which we need to turn off the transistor as the inductor is FULL of flux. Keeping the transistor turned on for a longer period of time will just waste current.
The transistor is now turned off and you can consider it is removed from the circuit.
The current ceases to flow and the magnetic flux collapses.
This collapsing magnetic flux produces a voltage in the winding that is opposite to the original voltage and because it collapses very quickly, the voltage is very high. It can be 5 times higher or 100 times higher or even 1,000 times higher.
It depends on the magnetic material of the core and a number of other factors. This is called the "Q" factor or Quality factor of the inductor and is one of the amazing things in electronics.
In our case the voltage is over 18v . But we do not want a voltage this high and you will see how we use this voltage in a moment.
We pass it though a diode to charge an electrolytic. The diode prevents the voltage on the electrolytic passing back into the transistor/inductor circuit and discharging.
The electrolytic gets charged with the energy of the spikes and will charge to almost 18v. To prevent this, we detect when the electro is 5v and turn off the oscillator via the "sense" line.
When the voltage drops below 5v, the oscillator is turned on again.
The circuit is called a "flyback" circuit because we use the high voltage developed during turn-off to deliver a voltage to the output.
It can also be called a "boost" circuit.
The other sections of the circuit have already been discussed.
CHARGING THE CELLS
The two solar panels are connected in series to charge the two 1/3 AA Ni-Cd cells.
1/3 AA Ni-Cd cell
The two 1.2v NiCad cells have a voltage across them of about 1.3v +1.3v when charged and this rises to 2.7v when the panel starts to charge them. This is called a "floating charge" and the voltage developed across a cell when it begins to charge. This voltage has to be taken into account when supplying a charging voltage. On top of this we have a diode to prevent the batteries discharging into the solar panels (when no light is present) and this makes the panels need to produce over 3.3v to start the charging process.
With a high level of sunlight, the panels will deliver a charge-current of about 35mA. Depending on the number of hours of sunlight compared to the number of hours the project is required to deliver 5v, the maximum amount of current you can draw is determined by the following:
The cells have a 130mAh capacity and if you charge them at 35mA, it will take 4 hours.
On most days the cells will be fully charged in this time and you can allow the project to draw about 20mA during the charging process and still produce fully-charged cells on a bright day.
This gives 8 hours of daytime use.
The night-time use must come from the cells. If you draw 5mA from the 5v output, the current from the cells will be 13mA to 18mA and they will last a further 8 hours. This gives a total of 16 hours of use per day @5mA.
This is only a very small current but the project is intended for monitoring where it is turned on for a very short period of time to collect data and store it or transmit it via an RF link.
You cannot expect too much from a $10.00 solar project with battery back-up.
ASSEMBLY
The parts are placed on a small matrix board 8 holes x 10 holes. The PC board from the Garden Light is cut so that only the chip and surrounding lands are on the board.
This board is then connected to the matrix board via 4 short lengths of tinned copper wire.
All the other components are fitted to the matrix board as shown in the diagram. It is a simple matter to join each of the components under the board with fine tinned copper wire (included in the kit).
The top of the Matrix Board showing the
placement of the parts
The underside of the board is very messy
and the parts need to be re-laidout so
that no wires cross over. It can then be made
into a PC board.
TESTING
When the power is applied, the output voltage will rise to about 5v. The circuit needs a slight load to prevent hunting and a 1k resistor will draw 5mA.
If the load is removed, the output will hunt and the current consumption will drop to less than 1mA.
There are lots of different Garden Light circuits and you may need to adjust the value of the voltage-divider to get the output voltage you need for the circuit or the chip you are using.
You need to check the voltage on no load to make sure it does not rise above 5.5v if you are using a microcontroller. If it rises above 5.5v and is not stable, you can add a white LED and red LED in series to get a zener voltage of 5v1. Alternatively you can set the voltage to below 5v and prevent over-voltage.
We show circuits of Solar Garden Light the product form chiana >>
Solar Garden Light Set
cheap price Solar Garden Light circuits in this article perform 2 functions:
1. They charge a battery and
2. Turn on a high-bright white (or yellow) LED at dusk and off during daylight hours.
The two circuits are completely different in design and we will see how different designers tackle the same problem.
Firstly we will discuss the circuit above. It is called Circuit 1.
Here's the clever part: The circuit doesn't deliver a DC voltage to the LED but a high-frequency pulse. This creates the same brightness from the LED (as a constant DC voltage) while needing less than 50% of the energy. It also allows a single cell to be used.
Also, the circuit does not have a dropper resistor for the LED and this further increases the efficiency.
The third clever idea is the use of a single rechargeable cell - even though the white LED requires 2.3v.
And the final clever feature is the use of 4 solar cells to charge the rechargeable cell.
By using a single cell, it is only necessary for the solar panel to produce a voltage above 1.2v for charging to occur. This can be achieved with 3 cells, but if an additional cell is included, the voltage from the panel will rise above 1.2v when the day is not very sunny and thus the battery will be charged almost all the time during the day. http://www.youtube.com/watch?v=5iSH7pe8YTE Solar Garden Light
On a very dull day the charge current will be as low as 1mA and increase to over 9mA under very bright sunlight.
The solar panel also performs another function. It turns the LED on and off.
As soon as the voltage from the panel rises above 0.7v, the circuit detects this and turns off the oscillator. This means energy from the battery is not used during the day.
The first transistor is called a "cut-off transistor." It turns off the oscillator section by robbing the base of "turn-on voltage."
When the LED is illuminated, the circuit consumes 10mA, and if you work out the number of night-hours to daylight hours, you will see the LED will illuminate for about 6 hours. This is sufficient for most applications.
CURRENT LIMIT RESISTOR
Although a current-limiting resistor between a solar panel and a battery is technically needed, it is not necessary if the battery will not be overcharged. In our case, the solar cells will not overcharge the battery.
THE SOLAR CELL
The SOLAR CELL actually consists of a number of cells as each cell only generates about 0.5v to 0.6v.
The Solar Cell in our model consists of 4 cells and produces approx 2v with bright sunlight.
The short-circuit current produced is about 30mA and although this is not the correct way to determine the current capability of the cell, it has been given to help you select a suitable cell (or set of cells). The current will drop considerably when the solar cell is connected to a 1.2v battery via a diode and our project delivered 8mA.
HOW THE CIRCUIT WORKS
The circuit consists of two stages. The first stage is a "switch" or cut-off device. It detects a voltage above 0.7v from the solar panel and the resistance between its collector-emitter terminals reduces to a very small value.
The 10k resistor allows the voltage on the solar panel to rise above 0.7v during bright sunlight, while the 100k discharges the 100p when the voltage is very low and the capacitor holds a charge to keep the transistor turned on when the voltage is "high".
When the resistance between the collector-emitter terminals of the first transistor is low, it is turned ON, and the second transistor does not get enough voltage on its base for it to operate as an oscillator.
The function of each component
The purpose of the first transistor is to keep the second stage OFF when the solar cell detects sunlight.
This allows the energy from the solar cell to be passed to the rechargeable battery.
The second transistor is an oscillator.
To see how it works we remove the first transistor.
The second transistor works by itself. The components in the circuit are: the transistor, the two chokes, the 6k8 resistor, the 1n2 capacitor and the LED.
An oscillator needs feedback called POSITIVE FEEDBACK. Positive feedback creates noise or "oscillation" in a correctly designed circuit.
An oscillator must be self-starting and the circuit in this project starts to oscillate by detecting a voltage on the base.
The transistor amplifies this and a larger waveform (larger voltage- change) appears on the collector. This is then passed to the base so that oscillation continues.
For oscillation to occur, the feedback signal must be delayed by a small amount of time.
This small amount of time determines the frequency and the feedback signal has another feature (or characteristic). It is presented to the base with an opposite polarity to that on the collector. To be more precise, the voltage must be moving in the opposite direction. This is called "180° out of phase."
This is achieved by the inductor and the 1n2 capacitor. We all know a capacitor creates time to charge, but an inductor also has a delay-factor.
A resistor does not have a delay-factor, as a voltage at one end of it will appear immediately at the other end, so we can explain the delay-time for an inductor by connecting an inductor in series with a resistor.
There have been many technical descriptions on how an inductor delays a signal, but never a simplified description.
Here is a simple way to understand how an inductor creates a delay.
In the following animation, you will see how the signal (the voltage) is delayed:
The main feature of this animation is to show an inductor effectively GROWS when an applied voltage is delivered to it by producing a back-voltage and thus the voltage at its other end does not change until the core is saturated. This understanding is most important in the circuit we are discussing as the top lead of the inductor is taken from a low-voltage to a high voltage by the action of the transistor when it is turning ON and OFF. As the top lead is taken from one voltage-level to the other, the lead connected to the capacitor does not see this rapid change, but continues in the cyclic process of charging and discharging the capacitor. That's why this circuit is so difficult to understand.
Let's look at the characteristic is the inductor in more detail:
The voltage applied to the inductor starts at zero. As it rises, the turns of wire on it produce magnetic flux that cuts the other turns and this action produces a voltage that opposes the incoming voltage, and a surprising thing happens. The resulting forward voltage is very small and this causes very little current to flow. Thus the voltage across the resistor does not change. This is similar to saying the waveform does not appear at the other end of the inductor. As the waveform rises further, (the applied voltage increases) the core of the inductor becomes saturated. At this point it cannot produce any more flux. The opposing voltage (produced by the expanding flux) is reduced and this allows a higher current to flow. This causes an increase in the voltage across the resistor. If the resistor is replaced by a capacitor, the capacitor would see a delay before it starts to charge. When the inductor is combined with a capacitor, the two components form a circuit that delays the signal to the base by 180° and the circuit oscillates at a frequency of about 500kHz.
The operation of this circuit can be found in text books under the heading Hartley Oscillator.
But it's a bit more complicated than first meets the eye as the inductor in the positive rail assists in the generation of the waveform.
Thus the circuit is beyond the scope of our discussion.
The only two things you need to understand are:
The in-rush of current for a capacitor and an inductor.
When a capacitor is connected to a voltage-source, the initial in-rush of current is high and it gradually decreases to zero as it charges.
When an inductor is connected to a supply, the initial in-rush of current is small and gradually increases.
The waveforms across the capacitor and LED are shown in the following diagrams:
The other feature we can discuss is the function of the top 0.47mH inductor.
When the transistor turns off, the magnetic flux in collapses and it produces a high voltage.
This voltage is high enough to illuminate the LED and the graph shows that when the LED is removed from the circuit, the voltage produced by the inductor has a peak of about 3.5v. The area under the peak represents energy and this is absorbed by the LED to produce light. The LED also reduces the peak to 2.3v as this is the maximum voltage (or characteristic voltage) of a white, super-bright LED.
Make an effort to buy a Solar Garden Light from a $2 shop and pull it apart, just to see how it works. If you have a CRO, you will be able to view the waveform on the 1n2 capacitor and across the LED. The waveform across the capacitor is an incredible 10v p-p with part of the waveform going negative by 4v. During the negative excursion, the transistor is turned off and the magnetic flux produced by the current-flow in the top inductor collapses very quickly and produces a high voltage that has an opposite polarity to the energising voltage.
This voltage is passed to the LED and light is produced.
The short pulses of energy delivered to the LED occupy about 20% of the total time but the energy they deliver produces a light-output equal to a constant DC voltage. By delivering short pulses, only about 30% of the energy is needed to produce the same illumination as a constant voltage.
Now we will cover circuit 2:
Circuit 2
Solar Garden Light-2 consists of three transistors. The first two transistors form a positive-feedback amplifier and the third transistor is a common-emitter amplifier.
The circuit only needs the first two transistors to create an oscillator.
The circuit turns on when the photo resistor fails to detect light and its resistance effectively goes very high. This allows the 47k base resistor to turn on the transistor. The voltage rises on the base as the 100n charges and the transistor turns on.
This action turns on the BC 557 transistor and the voltage on the collector rises.
This increases the current into the base of the first transistor via the 100k resistor and the two transistors would stay in this state if it were not for the 330p capacitor.
The 330p also pulls the base of the BC 557 towards the 0v rail and this assists in turning on the BC 557.
This occurs when the the first two transistors turn on as the emitter-follower third transistor is also turned on during this action.
The 330p is pulled low during this action and it quickly charges. When it becomes charged, the "turn-on" current for the BC 557 is reduced and it turns off slightly.
This action reduces the current through the 100k feed-back resistor and the first two transistors begin to turn off.
The third transistor is also turned off and the current flowing through the inductor is reduced. This causes the magnetic flux to collapse and produce a voltage in the opposite direction.
In the first instance, the voltage on the top of the inductor was more-positive than the voltage on the lead connected to the collector.
When the current is reduced, the voltage collapses and produces a voltage that is negative at the top lead and positive at the lead connected to the collector.
This is exactly the same as connecting a battery to the positive rail of the project with its negative on the top rail and positive to the collector.
This produces a very high voltage on the collector of the transistor and is passed to the base of the BC 557 via the 330p. The BC 557 is effectively turned off completely. The result is the first two transistor are fully turned off and the third transistor is also fully tuned off.
This is exactly the same as removing the third transistor from the circuit.
The inductor produces a voltage (in the form of a spike) that is higher than 2.1v to illuminate the high-bright yellow LED - in fact it is much higher but the LED converts this energy to light.
You cannot measure this voltage with a multimeter as the voltage is produced in the form of spikes.
If you remove the LED, a CRO will show the spikes are higher than 40v.
This makes the circuit ideal for converting to a 5v supply as shown in our other article: Power Supply 5v Solar.
NOTE:
An email from a reader asks about the inductors:
http://www.prc68.com/I/EOG.shtml
If you have a circuit as shown in the following photo, that is is powered by 3 AA cells, the circuit does not need any inductors as the 4.5v is sufficient to illuminate white LEDs.
CONCLUSION
Both circuits are much more complex than you would expect, in such a simple product. But that's the miracle of electronics.
You will see the same level of sophistication in many products, such as talking birthday cards, toys, LED torches, etc.
There may be other circuits in these Garden Lights as the author has seen at least 10 different types.
The main thing to look for is the size of the solar panel.
The solar panel in Circuit 1 produced a current of 25mA with full sunlight. The current produced by the solar panel in circuit 2 was 50mA. It had twice the amount of active surface.
Solar Garden Light Set
Add caption
This is just another product that costs less than buying the individual parts from an electronics store.
Now you can see why the hobby of electronics is dying, just when electronics is e-x-p-a-n-d-i-n-g! But that's no reason to give up. There is still an enormous demand for new ideas and gadgets.
Great panel
