Solar Voltage Monitor. Start Up Project 32


1AHow can we confirm the voltage level from the Solar panel ? A 12 Volt Solar panel generates around 20 V DC Open circuit voltage in bright sunlight. The voltage gradually increases from 6 am and peaks in the mid noon between 11 am and 3 pm. Then the voltage from the Solar panel drops to zero around 6 p.m. So we get sufficient voltage for charging the battery for 4-5 hours only in a day. The 12 V battery requires more than 14 V for proper charging. Its current should be above 500 mA. The current rating of the Solar panel is represented in terms of Watts. As a general rule, for each watt, the current will be 80 mA. So a 10 watt Solar panel gives 800 mA current. This depends on the availability of sufficient voltage from the Solar panel. Many factors like corrosion of contacts, loose contacts in connections, dust on the panel etc will affect the current flow from the panel. So how can we monitor the voltage level from the Solar panel. A volt meter can do but we can make a simple LED Meter for this. Its cost is less than Rs.80. It has three LEDs. The Green LED lights, if the voltage from the Solar panel is above 13 V. Yellow LED lights if the voltage is between 9V and 11 V and Red LED lights, if the voltage is below 9V. Remember, the Solar panel is efficient only when the Green LED lights between 11 am and 3 pm.
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Portable Solar Generator. Start Up Project 16


7AWhat will do if you are in a place where AC is not available to power your gadgets ? You can carry this Portable Solar Generator to a Picnic spot where AC is not available. It lights a CFL to provide sufficient light and AC for charging Mobile Phone, Tablet etc and can even play a small CD player. Alternately you can use the unit in home during Power Outage days. It converts the 12 V DC from the battery to 220V AC to light the CFL. It has a bulb holder to fix the CFL and an AC outlet to tap AC for other purposes. It uses a simple 20 Watts CFL Driver board to converts DC to AC. The battery can be charged using a 12 V Solar panel or 12V DC Adapter. The battery used in this unit is 12V 3 Ah (3 Ampere Hour) rechargeable Lead acid battery which can power the CFL many hours.
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Solar Day Light. Start Up Project 15


1Why use lights during day time to waste electricity? Sometimes we need it in some rooms. We can go for a “Green Solution” to harvest Solar energy for lighting an LED light during day time. Just fix a small Solar panel and a Strip LED. It needs no battery  because the solar panel itself acts as a battery. It generates DC voltage when the Photons of the Sunlight energize its semiconductor. So the light remains on throughout day time. You need only a 12V Solar panel and a Strip LED. Connect and relax. It will do its work for 20 years. No circuit is in it and you can easily connect it.
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Solar Power Outlet. Start Up Project 4


17AWhy wasting electricity for charging USB devices including Mobile phone? Sun is there to give power for this. Install a Solar Power Outlet in your home to harvest solar power for charging all USB devices in day time. Its cost is only Rs.500 and you get unlimited day power for more than 25 years to charge all USB devices. The expensive part of the project is Solar Panel. A 12 Volt 5 watts Solar panel costs around Rs.400 because the current rate is around Rs.80 per watt. The remaining components costs only Rs.100. So by spending Rs.500 initially, you can charge all your USB devices at the expense of only 6 Paisa per day . The calculation is for 25 years (50,000 Paisa / 9000 days = 5.5 Paisa). So hurry up to make this project.
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Solar Laptop Charger. Home Utility Circuit 17


IMAGEHere is a simple solution to charge your Laptop, Tablet, Notebook etc outdoor. A 12 V 10W Solar panel can very well charge the Laptop battery if a DC – DC Booster module is connected between the Solar panel and the Laptop battery. It is a very good charger if you go for a Picnic site where AC is not available to charge the Laptop. It is cool, make it.
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Mini Solar Light. Home Utility Circuit 5


IMAGEYou can make this Solar light using only a few components. You need a 3 V Solar panel, two 1.5 V Rechargeable Pen cells and few other components. It is a miniature Portable Solar light that can be placed anywhere like garden, porch or even in an outing place. During day time battery charges from Solar panel and at Sunset, White LED turns on for around 6 hours.
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Voltage Monitor for Solar Panel. Design Note 46


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Here is a simple circuit to monitor the voltage level in Solar panels. Usually a volt meter test is done during the installation of solar panel and then after, the panel remains unattended. If the solar panel is not providing sufficient voltage for charging the battery, that will permanently destroy it. A 12 volt Solar panel gives maximum of 22 volts DC in bright sunlight, which drops to around 16 volts when the load is connected. So a voltage level around 16 volts is necessary for charging the 12 volt Lead Acid battery. But the voltage output from the solar panel may reduce due to the accumulation of dust on the panel and corrosion of terminal contacts. These remain unnoticed ,so only when the battery fails ,we note this. This simple circuit solves the problem. If the solar panel  gives above 15 volts with the battery connected, the LED remains off. When the voltage from solar panel drops below 15 volts, LED turns on to indicate low voltage. This usually happens when the sunlight is low, but if the LED remains on in bright sunlight also, it indicates low output from the solar panel. The circuit can also be used as Battery level monitor.
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