Archive for Category Alternate Energy

1. Inverters and BOS in Roof Top PV Systems

BOS, Balance of Systems and Inverters are integral parts of any Solar Power Generating unit. It is imperative that specified BOS and inverters are used for any given configuration of a solar power system for optimal energy efficiency. BOS includes the wires connectors, AJB’s etc. For Energy Efficiency, it is important to use the wires with correct thickness to avoid heat loss and voltage drop. Ohm’s law ( V=IR ) quantifies the voltage drop as a function of current and resistance. The figure below broadly indicates the wire thickness v/s current function to minimize the voltage drop.

The MPPT Charge Controller

MPPT (Maximum Power Point Tracking) Charge Controller tries keeping the panel at its maximum voltage and simultaneously produces the voltage required by the battery. A basic charge controller simply prevents damage of batteries by over-charging, by effectively cutting off the current from the solar panels (or by reducing it to a pulse) when the battery voltage reaches a certain level. On the other hand, a Maximum Power Point Tracker (MPPT) controller performs an extra function to improve your system efficiency.

What does the MPPT Controller Do ?

Besides performing the function of a basic controller, an MPPT controller also includes a DC to DC voltage converter, converting the voltage of the panels to that required by the batteries, with very little loss of power. In other words, it attempts to keep the panel voltage near its Maximum Power Point, while supplying the varying voltage requirements of the battery. Thus, it essentially decouples the panel and battery voltages so that there can be a 24 volt system on one side of the MPPT charge controller and panels wired in series to produce 48 volts on the other. Thus, offering the ability to provide some charging current even in dull conditions when a simple controller would not help much.

Inverter Efficiency

Solar PV system produces DC current, which is converted to AC using an inverter. Although inverters come with wide ranging efficiencies but typically affordable solar inverters are between 80% to 90% efficient.

Battery Efficiency

Batteries are needed for charge storage. Lead acid batteries are most commonly used.
Since lead acid batteries are usually charged at the float voltage of about 13.5 V and the discharge voltage is about 12 V, the voltage efficiency is about 0.88. In average the coulomb efficiency is about 0.92. Hence, the net energy efficiency is around 0.80

A lead-acid battery has an efficiency of only 75-85% (this includes both the charging loss and the discharging loss). From zero State of Charge (SOC) to 85% SOC the average overall battery charging efficiency is 91%- the balance is losses during discharge. The energy lost appears as heat which warms the battery. It can be minimized by keeping the charge and discharge rates low. It helps keep the battery cool and improves its life.

2. Roof Top Solar Power

We will be briefly providing details of some configurations that could be considered for roof top installations in Rural U.P, where power is acutely scarce.

Before we describe the various possible configurations, it would be pertinent to mention that judicious utilization of power goes a long way in saving costs and power units. For example, LED Lights consume only a fraction of energy as compared to the conventional lights/bulbs. Likewise, it would be prudent to chose your electrical devices that are energy efficient. Check their rating. One of the biggest power sump in any household is an Air Conditioner. So if you plan to run an AC on solar, it would be in your interest to go in for 5 star AC models. You could also consider hybrid AC models (which can run on DC)

For purpose of calculation, we will take the loads as follows -

  • Light/LED- 10w
  • Bulbs- 40w
  • Fan- 25-30w
  • Refrigerator- may use about 75w, but does not run continuously
  • TV- 60-100w
  • Laptop 15-25 w
  • 1 Ton AC (conventional)- 2000w
  • 1 Ton AC ( 5 Star or Hybrid)- 1000w
  • 1 KW Panels and I KVA Inverter, with 2 Batteries of 150AH- This STAND ALONE OR HYBRID configuration is for a very small household, wishing to run 3 fans, 3 LED lights and one small refrigerator etc. (**Calculated on intermittent running ( need based use) on a period of full day and night - 24 hours).
  • 1.5 KW Panels and 2 KVA Inverter, with 4 Batteries of 150AH- This STAND ALONE OR HYBRID configuration is for a medium size household, wishing to run 6-10 fans, 3-8 LED lights and one small refrigerator, a few hours of lap-top usage etc- (**Calculated on intermittent running ( need based use) on a period of full day and night - 24 hours).
  • 3 KW Panels, 3 KVA Inverter with 4 Batteries- For relatively bigger households

Our Inverters Specifications

  • DSP based control and MPPT Solar Charging
  • Pure Sine wave output and has less transfer time.(suitable for computer applications)
  • Inbuilt DC priority feature. When solar is present battery will not take any current from AC Mains
  • High efficiency & longer back up time
  • Withstanding surge of double the rating or more
  • Intelligent charging ensuring more battery life
  • Noiseless operation of fans, lamps and appliances
  • Overload Protection & auto recovery
  • Short Circuit Protection
  • Over temperature sensing
  • No load sleep: If the load is less than 10W the Inverter will go to automatic sleep and save power
  • Liquid crystal display for status monitoring
  • Battery Charging through both solar and Grid
  • Inbuilt solar priority system
  • High reliability
  • Intelligent solar Charger
  • Overload Protection
  • Short circuit protection
  • Auto Restart
  • High efficiency - green inverter
  • Generator Compatibility

3. Solar Battery Life

Battery Cycle Life is basically the number of charge - discharge cycles performed by a battery before its nominal capacity falls below 80% of its initial rated capacity. Key factors impacting cycle life are time t and the number N of charge-discharge cycles completed.

Temperature effects

Chemical reactions in the battery are driven either by voltage or temperature. . The higher the battery temperature, the faster chemical reactions inside the battery. High temperatures thus provide increased INITIAL performance, but detrimentally effect its life due to adverse reactions and bi-products. This results in a corresponding loss of battery life. The shelf life and charge retention depend on the self discharge rate and self discharge is the result of an unwanted chemical reaction in the cell. Similarly adverse chemical reactions such as passivation of the electrodes, corrosion and gassing are common causes of reduced cycle life. Temperature therefore affects both the shelf life and the cycle life well as charge retention since they are all due to chemical reactions. Even batteries which are specifically designed around high temperature chemical reactions, (such as Zebra batteries) are not immune to heat induced failures which are the result of parasitic reactions within the cells.

Depth Of Discharge (DOD) -

DOD, an abbreviation for Depth of Discharge, is used to describe how deeply the battery is discharged in each cycle. If we say a battery is 100% fully charged, it means the DOD of this battery is 0%, If we say the battery have delivered 30% of its energy, here are 70% energy reserved, we say the DOD of this battery is 30%. And if a battery is 100% empty, the DOD of this battery is 100%. DOD always can be treated as how much energy that the battery delivered. For Lead Acid batteries we do not recommend full discharge. This would shorten the cycle life of batteries . At a given temperature and discharge rate, the amount of active chemicals transformed with each charge - discharge cycle will be proportional to the depth of discharge. The relation between the cycle life and the depth of discharge appears to be logarithmic.

Charging Level

The cycle life of batteries can be increased by reducing the charging cut off voltage. This essentially gives the battery a partial charge instead of fully charging it, similar to working at a lower DOD as in the example above. The graph below shows the typical cycle life improvements possible.

Charging Rate

Battery life is also influenced by the charging rate.The capacity reduction at high discharge rates occurs because the transformation of the active chemicals cannot keep pace with the current drawn. The result is incomplete or unwanted chemical reactions and an associated reduction in capacity as noted in the paragraph on Chemical Changes above. This may be accompanied by changes in the morphology of the electrode crystals such as cracking or crystal growth which adversely affect the internal impedance of the cell. Similar problems occur during charging. There is a limitation as to how quickly the Lithium ions can enter into the intercalation layers of the anode. Trying to force too much current through the battery during the charging process results in surplus ions being deposited on the anode in the form of Lithium metal. Known as Lithium plating, this results in an irreversible capacity loss. At the same time, maintaining the higher voltages needed for fast charging can lead to breakdown of the electrolyte which also results in capacity loss. From the above we can expect that with each charge/discharge cycle the accumulated irreversible capacity loss will increase. Although this may be imperceptible, ultimately the capacity reduction will result in the cell being unable to store the energy required by the specification. In other words it reaches the end of its useful life and since the capacity loss is brought on by high current operation, we can expect that battery cycle life will be shorter, the higher the current it carries.

Voltage effects

Rechargeable batteries each have a characteristic working voltage range associated with the particular cell chemistry employed. The practical voltage limits are a consequence of the onset of undesirable chemical reactions which take place beyond the safe working range. Once all the active chemicals have been transformed into the composition associated with a fully charged cell, forcing more electrical energy into the cell will cause it to heat up and to initiate further unwanted reactions between the chemical components breaking them down into forms which can not be recombined. Thus attempting to charge a cell above its upper voltage limit can produce irreversible chemical reactions which can damage the cell. The increase in temperature and pressure which accompanies these events if uncontrolled could lead to rupture or explosion of the cell and the release of dangerous chemicals or fire. Similarly, discharging a cell below its recommended lower voltage limit can also result in permanent, though less dangerous, damage due to adverse chemical reactions between the active chemicals. Protection circuits are designed to keep the cell well within its recommended working range with limits set to include a safety margin. This is discussed in more detail in the section on Protection . Cycle life estimations normally assume that the cells will only be used within their specified operating limits, however this is not always the case in practice and while straying over the limits for short periods or by a minor margin will not generally cause the immediate destruction of the cell, its cycle life will most likely be affected. For example continuously over-discharging NiMH cells by 0.2 V can result in a 40 percent loss of cycle life; and 0.3 V over-discharge of lithium-ion chemistry can result in 66 percent loss of capacity. Testing has shown that overcharging lithium cells by 0.1 V or 0.25 volts will not result in safety issues but can reduce cycle life by up to 80 percent.

4. Home Solar Power Systems - Advantages

Without doubt pollution control is one of the greatest advantages of using Home Solar Power Systems. One does not have to be an ecologist to realize the severity of the environmental problems that affect our planet. The inter-related issues of fossil fuels, pollution and climate change- all affect us one way or the other. The advantages of Home Solar Power Systems are not limited to environmental effects, although they are very relevant. There are many other benefits of using solar PV energy in terms of costs, maintenance or energy independence. Whether you are interested in this energy source because of a profound environmental concern, or you are more attracted to the idea of low-cost energy and money saving, going solar can prove to be a remarkably smart idea.


Over-exploitation of the Earth's non-renewable resources ( fossil fuels ) will eventually lead to their paucity, and consequently, higher costs, not to mention the issue of extreme pollution. Turning to a renewable source of energy thus becomes imperative.

Solar energy is renewable

Solar Energy is a renewable source of energy - we can count on for the sun to keep shining for billions of years. Using Solar Energy will not diminish it.

Solar energy is clean

Unlike fossil fuels, energy derived from the sun is not polluting. There are no gas emissions- it is totally clean. It contributes to reduction of the greenhouse effect. Solar energy is one of the best way to protect the environment and reduce the negative effects of fossil fuels on the environment.

Low costs

Solar energy is almost free. Once you install a Home solar power system, you can enjoy free energy as long as the Sun is up in the sky. Yes, the cost of installing such technologies can prove to be a substantial investment, but in time, you will save a lot of money on energy. If you think long-term, the benefits are considerable. Abandoning fossil fuel energy in favor of a low-cost type of energy is common sense. Relying on solar energy, which is free, will lower electricity bills to an affordable level. In case you choose to produce all the energy your house needs using the power of the sun, you will save serious money on bills.

Low maintenance costs

The maintenance of a solar system is easy and cheap. After the initial investment in installing the solar system, the chances of spending money on it will be quite limited.

5. Renewable Energy from the Sun - Facts

Solar Power is an ecologically sound and desirable source of energy. Sunlight has been used by microbial, plant, and animal life as a primary energy supply. Photosynthesis is a process which also requires sunlight.

Earth's atmosphere absorbs about 3.85 million exajoules of solar energy. However by comparison, the entire use of electric energy, world-wide is about 56.7 exajoules annually. Thus, within a few hours, the earth receives more solar energy than people expend annually!

Renewable energy from the sun is a clean source of energy. In contrast to fossil fuels, using Solar energy doesn't discharge carbon dioxide or other types of harmful toxins into the environment. Furthermore solar energy is collected by almost every single form of life. Even animals bask in sunshine to warm themselves. Solar power is probably the most environmentally sound energy option attainable right now.

Every year, humans consume 467 exajoules of energy, mostly derived from fossil fuels. However, if we could capture just 10% of the renewable energy from the sun, we could replace all fossil fuel sources.

Solar Energy is the collective energy in form of heat and light energy emitted from the sun. Approximately 30% of this is immediately deflected by the atmosphere, and another 20% is absorbed into the atmosphere. However, approximately 50% of the solar energy reaches the earth's surface, where it fuels photosynthesis in plants, creates and maintains weather patterns and climates, as well as the temperature of the ocean, and generally speaking keeps our planet alive. All of this is accomplished without creating any pollution or destruction of natural resources.

In the last three decades, solar energy technology has developed at an accelerated rate. Solar energy is harnessed using PV solar power plants. Home Solar Power generation is now possible with rooftop installation of Solar panels. Solar energy can be employed to power practically any procedure you can visualize, from large-scale power generation for towns and cities to boiling a single pot of water.

Photovoltaic solar power plants use PV panel systems to produce electricity. This electric current may be used immediately or alternatively stored in batteries for later use. Battery storage is incredibly significant since it means it is possible to store solar power for use through the night or during cloudy or rainy days.

6. Sunny Side Up with Solar Energy

Apollo the mighty Sun God, brilliant yellow with a white halo, stands guardian to Mother Earth, as a provider of clean and green energy. Much like the “Florence Nightingale” He bears the magic lamp, waiting to deliver endless photons to all who care to harness.

Earth’s sources of Fossil Fuels are depleting faster than ever. The current outputs are falling short of the demand. Not to mention the ecological impact and carbon foot print. Burning fossil fuels releases pollutants like carbon dioxide, nitrogen monoxide, nitrogen dioxide, sulphur dioxide, carbon monoxide etc. These gasses have severe consequences on the habitats. A phenomenon called the “Acid Rain” is caused by sulphur dioxide. The smoking guns have been bellowing smoke rather too long, and I guess need to be silenced, to make our Mother Earth a healthier place to live in.

The Almighty Sun God, with his photonic generator offers us one of the much needed options out of this energy-dilemma. An article in NY Times recently published some eye-opening statistics. To make this planet cleaner, we need to re-think and re-plan our energy portfolio. The quaint source of endless energy is right there at the horizon. All we need to do is to have our sunny side up, with photo voltaic panels.