Tuesday, December 8, 2009

Solar Power Technology

Yep I back after 10 years almost!!!!!!!!!!!!!!!!!!!!!!!!!!
Yes it's me MAD SOLOR MAD

Introduction: Most of the electricity in India comes from fossil-fuels like coal, oil and natural gas. Today the demand of electricity in India is increasing  where as the reserves of the fossil-fuel are depleting every day. The demand of electricity is already more than the production of electricity. We can feel this fact from the electricity-cuts during summer. Luckily Sun throws so much energy over India, that if can trap few minutes of solar energy falling over India we can provide India with electricity for whole year. Most parts of India get 7 KWH/ sq-meter of energy per day averaged over a year.

                We have gathered the most advanced techniques in solar world to provide cost efficient systems.  We are working towards our dream to eliminate the problem of electricity in India. This article gives a glance of our technology. This article does not have all the details of our technology and is a mere introduction.

Solar Cell :  A Solar cell is made up of silicon semiconductor wafer. The Solar cell generates current when light strikes on it. There are lots of technologies being used for PV cells today. Poly-Crystalline is the most widely used technology. As of today commercial  Solar cells have efficiency of 17% at max. Usually the poly-crystalline solar panels have 15 % efficiency. The power generated by a solar-cell is function of lots factors that are beyond the scope of this article. Our technology extracts every drop of  power from these solar panels to make our systems price-effective.

Solar Panel: A Solar panel is nothing but number of solar-cells connected in series and parallel to get desired voltage/current. Besides this, these solar cells are encapsulated in weather-proof material to guard the solar-cells against rain, hail , dust, wind etc. Most of solar panels are framed in aluminum-frame to provide structural re-enforcement and facilitate installation. PV arrays or panels are the most expensive part of the solar power system.

    We have done extensive research on Lead-Acid batteries and  Solar-cells to design optimum system that can give maximum efficiency and provide long life to batteries. Following are the few features of our systems.

1. Enhanced Solar Charge Controller: It seems very easy at first, hook the Solar Panels to battery or a load. But it is very complicated to extract energy from solar panels and feed it to batteries for use during night. The very first charge controllers just connected the solar panels to battery and switched off the panels when battery reached a specific voltage. Such systems waste significant part of the solar energy and kill the batteries. You can see that batteries used in inverters in homes die within 2-3 years where as battery life is much longer.

2. Temperature compensation: The characteristics of a Lead Acid battery change with battery temperature. The temperature of battery is decided by ambient temperature and the heat produced from internal resistance. For example a typical lead acid  battery is fully charged at 13.6 Volt at 45 Degree Celsius and 14.7 Volt at 0 Degree Celsius. India has extreme temperature conditions, during summer the temperature reaches 47 Degrees and in Winter it touches 5 Degrees. Under these conditions if we don't use temperature compensation we will overcharge the battery during summer resulting in excessive gassing and reduced battery life. During winter the battery will remain under-charged. Our systems monitor the battery temperature continuously and adjust the battery charging accordingly. 

3. Three stage battery charging: Our systems will use advanced three stage battery charge controllers to provide maximum efficiency and longer battery life. The three stage battery charger can be explained using simple analogy. The three stage charging is just like filling an empty pot with water. In starting we fill the pot with maximum speed and as the pot gets near to full , slow down the flow of water to gently top off the pot without spilling.

Bulk Stage. In the stage maximum current from the solar panels is transferred to batteries as inferred by the word "bulk".

Absorption Stage: In this stage, only that much charge is given to the battery as much battery can take. The battery is not forced to take the         charge it does not want to take.

Float: In this stage the battery is trickle charged to maintain the charge.

4. Batteries: Lead Acid batteries are most popular for storing electrical energy when the application is stationary. You would have seen the Lead Acid batteries used in inverters. Lead Acid batteries can be divided in two basic categories.

Automotive Battery: These batteries are used in  automobiles like cars, trucks for starting the engine. Lots of people use these batteries for inverters. These batteries are not suitable for inverters at all. These batteries are designed to provide high current for short time like starting the engine. If they are fully discharged repeatedly, just like in inverters, they will die soon. As you see most of cheap inverter batteries die in  2 years. Automotive batteries are designed for a discharge of 10%.

Deep Cycle Batteries: These batteries are designed for deep-discharging. These are the batteries designed for inverters and Solar Power systems. We will be using only high quality Deep-Cycle batteries in our system. These batteries are designed to provide low-current for long period and are built to survive deep-discharges. Our systems will provide a battery life of 7 years and above. There are further classifications in the deep-cycle batteries like flooded and VRLA etc. More details on the batteries are beyond the scope of this article.

5. Inverter:  The inverter is used to convert the DC power from solar panels to 220V AC. There are two types of inverters in the market

a) Modified sine Wave: These inverters produce modified sine wave. The harmonic distortion in these inverters can be as much 50%. These are cheaper and are and more efficient inverters. Most of the inverters used in homes are modified sine wave. These are good for most of the appliances. But if  these inverters are used for long time motors-based appliances run hotter. Also lots of appliances don't run on modified-sine wave at all like medical equipment.

b) Pure sine Wave: These inverters provide pure sine wave just like the mains power. These inverters have bit less efficiency than the modified sine wave, but these inverters can run all kind of appliances as these inverters provide pure sine wave. These are usually 2-3 times costlier than modified-sine wave inverters.

We are planning to use the pure-sine wave inverters in all major systems, so that all appliances  can run on the power they are designed for. Appliances run cooler, run silent on pure-sine wave inverters and enjoy a long life.

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