Simple Solar charger circuit project using transistors

A very simple solar charger circuit project can be designed using few external electronic parts . This simple solar charger circuit is capable of handling charge currents of up to 1A. Alternate component values are given in the figure for lower current applications.

Circuit diagram:

 Solar charger circuit project using transistors circuit diagram

The only adjustment is the voltage trip point when the current is shunted through the transistor and load resistor. This should be set with a fully charged battery. As the transistor and R3 have the entire panel’s output across them when the battery is fully charged, all of the current from the panel will be going through R3 and the Darlington transistor TIP112, so these must be well heat sunk. Adjust R1 for the trip point, usually 14.4 V – 15 V for a 12 V SLA or a 12 V Ni-Cd battery.

source : Link

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Open Source Solar Data Acquisition System

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 below 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. [Link]

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Sensitized Solar Cells Based on Zinc Compounds

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. [Link]

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Simpled Solar Powered Lithium Ion Battery Charger Circuit

The circuit below feeds a controlled current and voltage to a 3.6v lithium ion battery. The current is limited to 300ma and the voltage is limited to 4.2 volts. The circuit uses a LTC1734 IC from Linear Technology. No diode is needed between the circuit and a 6 volt solar panel. Some very nice 6 volt solar panels are available from www.plastecs.comTheir SP6-200-12 cranks out about 1 watt while the SP6-300-12 can produce about 2 watts. Assuming a 6 hour sunlit day, the 2 watt panel will pump about 1.8 amp-hours into a battery.

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Solar Cell Voltage Regulator Circuit Diagram

This is a Simple Solar Cell Voltage Regulator Circuit Diagram. This device is designed to be a simple, inexpensive ‘comparator’, intended for use in a solar cell power supply setup where a quick ‘too low’ or ‘just right’ voltage indicator is needed. The circuit consists only of one 5V regulator, two transistors, two LEDs, five resistors, two capacitors, and one small battery. Although a 4-V battery is indicated, 4.5 V (3 alkalines in series) or 3.6 V (3 NiCd cells in series) will also work. 

 Solar Cell Voltage Regulator Circuit Diagram

 

The specifications of voltage regulator IC1 are mainly determined by the size and number of the solar cells and the current pull of the equipment connected to the output. Here the low-drop 4805 is suggested but other regulators may work equally well as long as you observe the output voltage of the solar cells. Transistors T1 and T2 are complementary types i.e. one each of the pnp and npn variety. 

Although the ubiquitous BC557B (pnp) and BC547B (npn) are indicated, any small-signal equivalents out of the junk box will probably do. The values of voltage dividers R1/R6 and R3/R4 may need to be adjusted according to the type of transistor and its gain, or according to the desired voltage thresholds. Using the resistor values shown in the schematic, LED D2 turns on fully when the voltage is just above 5 volts. 

LED D1 turns on when the voltage drops below 4.2 volts or so. Between those two thresholds, there is a sort of no man’s land where both LEDs are on dimly. A buzzer or other warning device could be connected across the terminals of LED D1 to give a more substantial warning if the voltage drops below operating limits. The current consumption of the circuit is about 20 mA at 5 V, and it decreases with the voltage supplied by the solar cells.

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Solar Panel Current Meter Circuit Diagram

This circuit is used to measure the current from a solar panel. It has very low power loss for currents in the 0-10A range. It also works as a general purpose DC current meter. The circuit can be used on either the positive or negative side of a DC circuit.

Solar Panel Current Meter Circuit Diagram

Specifications

Measured Current: 0-10 Amps DC, can be increased by changing the resistors.
Circuit Voltage: Will work with DC circuits at any practical voltage.
Accuracy: approximately 2% with a high quality meter movement.

Theory

The current to be measured flows through the 0.01 ohm resistor, this causes a small voltage drop across the resistor. 10 amps of current will produce a 100mV voltage across the resistor. The 100 microamp meter is wired in series with a 50 ohm fixed resistor and a 500 ohm variable calibration resistor so that it can measure the voltage drop.

The 500 ohm variable resistor is used to adjust the meters full scale reading. The 50 ohm resistor limits the maximum current through the meter. The series resistance of the meter, the 500 ohm (or less) variable resistor and 50 ohm resistor should total 1000 ohms. Different meters may require a different variable resistor to achieve the 1000 ohm value.

Construction

Build the meter into a metal box with the meter and two connectors mounted on the outside of the box. Be sure to use connectors and wiring that are large enough to handle the full amperage from your PV array.

Alignment

Put the meter circuit in series with a known current meter such as a digital VOM meter set to measure current. Run a known current through both meters. Adjust the 500 ohm resistor until both meters read the same current. A good way to get a known current is to put a 12V lead acid battery in series with a 2 ohm 100 watt current limiting resistor. This will produce approximately 6 Amps of current. Put the two meters in series with this loop and adjust for the same reading. Beware, the resistor will get fairly hot in a short time.

A PV panel is naturally current-limited and would also work well for alignment of this meter. Just wire the panel and two meters in a series loop and adjust the calibration potentiometer for the same reading.

Use

Connect this circuit in series with a nominal 12V or 24V solar panel array. The meter can go in either the positive or negative side of the solar panel circuit. Negative side wiring can be safer from short circuit hazards. The current flowing through the solar panel to the load will be shown on the meter.

Note that the wiring in a PV system is slightly resistive and will have a measurable voltage drop. You can take advantage of that by using the systems wiring in place of the 0.01 ohm resistor. Just connect a small signal-wire to two places on either the positive or negative side of your PV systems feed wiring and send that to the meter and its two series resistors. Typical connection points would be at the PV panels negative terminal on one side and where the PVs negative line connects to the charge controller on the other side.

The voltage drop across the PV wiring will vary with the wire gauge, the wire length and the maximum PV current. It may be necessary to adjust the value of the two series resistances and possibly the meter rating depending on the current to be measured.

Parts

1x 100 microamp DC meter
1x 0.01 ohm 5 W resistor
1x 50 ohm 1/4 W resistor
1x 500 ohm 10 turn variable resistor
2x banana plugs or a 2 pin screw type terminal block.
1x metal box

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