Posts Tagged ‘solar’

1.5KWp Solar Power Plant

April 22nd, 2013 3 comments

Another Solar Power Plant project @Mogappair, Chennai

This time, I have helped a friend of mine to setup up the power plant for his home.  He had given a requirement to run everything in his home except the heavy duty equipment like A/C, Microwave Oven, Water heater & Washing machine. While measuring the load requirements, he had a peak load of about 1.5KW and an average load of ~600W and at nights the load was <200W average.

This time, I wanted to get a simplified inverter solution that does not require and interaction per se for the end user. So, we have procured a 2KW ESU inverter from Emerson, which was priced as Rs 55000/-.This inverter model comes with an inbuilt 48V/35A MPPT controller and a unity PF 2KW power inverter.  So, for these models of Emerson 2KVA is 2KW as the PF is 1.

Although Emerson has a good track record of quality products, their service customer care is outsourced, who do not function very well. Also the delivery time for the inverter is 5-6 weeks, but on paper they say 4 weeks. For the Mogappair area, the service is handled by Sri Nandees Technologies, who technicians on call are pretty good and responsive.

As usual, we procured the batteries (4x180Ah) from Sharana batteries for Rs 54000. Since my last installation, the price of batteries went up by ~5% for all the battery brands.  And the panels (24v/250Wp x 6) were procured from Akshaya Solar @42/watt for Rs 63000 and the structures for planting the panels were also got from Akshaya Solar for additional ~Rs 10000. And for the electrical works and civil works, we spent another Rs 18000.  Overall, we have finished the entire project for Rs 200,000 all inclusive.

Thanks to our electrician Mr. Raja  & vendors (Mr. Raju @Akshaya Solar, Mr. Aruldass @Sharana batteries, Mr. Karthik @Sreenandees, Mr. Jayaraj @Emerson) who helped us see this project through.  Incidently, this is the only domestic installation in the 1.5KWp range in the entire Ambattur, Avadi, Mogappair, Padi, Anna Nagar range AFAIK. 🙂

1KWp Solar Power Plant

January 30th, 2013 22 comments

Phew! What a relief!

I have just finished installing a 1KWp solar power plant in my apartment.  It was an wonderful and tiring experience getting everything to work together, ofcourse with the help of several kind people who helped moving on with the work.  I think, my installation is the first domestic installation for a capacity >1KWp in my entire area, that is Thirumullaivoyil; may be the first in Ambattur + Avadi townships.  Whatever be it, I am very happy that I could get it up and running as per the plan.  The power plant can produce upto 4-5KWh everyday in winter+sunny and may be 5-6KWh in summer.  I have been able to attach everything in my home except for Fridge, Ovens, Water heater, A/C and washing machine.  Yeah! Mixie, Coffee Maker, Wet Grinder, Computers, Water purifier run in solar at my home!  I tried attaching Fridge to the unit, but the backup time in the nights drastically reduced.  By the way, the solar power supply is 24hours through out.  The secret is that the excess power produced in the day are backed up in huge batteries, so that the saved energy is dispensed through out the night for powering my bed room and other low power night utilities.

Things to procure for this DYI project:

  1. Solar Panels: There are several variety of panels available, but always choose polycrystalline (aka multi-crystalline) panels, as there are very efficiently within 30 degree deviation of sunlight inclination angle.  If you go for monocrystalline, they are efficient only when the sun is right on top of them, so you are forced to install a solar tracking device for an additional cost.  I had procured MNRE approved panels for Rs 46/watt including transportation and taxes from Akshayasolar.  My setup has 12V 150Wp x 6 and 100Wp x 2, put together 1100Wp of bright power.
  2. Inverter: There are several varieties of inverters available in the market. Solar Inverters are the ideal choice here, but for my specification I could not get a solar inverter within my budget.  Typically solar inverters are priced around Rs 30000 for a 1KW capacity.  So, I had decided to go to regular sine-wave inverters and convert that to a solar inverter myself.  To convert an inverter to a solar inverter, I had to get a solar charge controller and fabricate a control circuitry.  I have bought a 24V, 1.4KVA Amaron Inverter for Rs 7000, with 2 years warranty.  A typical inverter has a power-factor of 0.7 to 0.8, so I could load upto 1000W comfortably without frying the inverter.
  3. Batteries: This is the most critical part of any ESU (Energy Storage Unit), where the power is stored during surplus and released when solar incoming reduces.  On the contrary, there are EEU (Energy Export Unit), which directly converts the energy derived by the solar panels into useful power for consumption or resale back to the grid.  TANGEDCO does not buy from installations less than 1MWp, so ESU is my only option.  So storing the power, the popular choice is Exide Solar Tubular batteries.  But, I chose Sharana Batteries because their manufacturing unit is in Ambattur Industrial Estate, and their service guarantee was better than what Exide offered.  While buying batteries, one should be very careful about the capacity rating of the batteries.  By capacity, the common misnomer is the AH rating.  AH rating tells the current limits of a battery, but the capacity rating is mentioned as Cxx (eg: C10, C20, etc).  Typically, a 180AH/C20 battery is same as the 150AH/C10 battery or 100AH/C5.  In C20 rating, if the drain current should be 9A, the battery would supply energy for 20 hours.  The same battery would serve for 8.33 hours only if the drain current is 18A, but you would expect it to serve for 10 hours.  Likewise, the same battery would serve only for 2.77 hours, if the drain current was 36A where you would expect a backup time of 5 hours (see here the capacity has halfed!!).  I have purchased 2x180AH @C20 tall tubular batteries from Sharana with 2 years warranty for Rs 26000.
  4. Charge Controller: There are two types of charge controllers available namely PWM, MPPT. Solar panels, although rated as 12V, they generate voltages upto 21.6V (open-circuit).  They are optimal at around 16.4-17.4V, which is called the maximum power point.  In order to leverage the maximum power from the controller, I used MPPT charge controllers.  For 1.1KW at 24V, the Imax is 50A, but assuming 80% efficiency for panels, 40A MPPT is sufficient.  I got 40A 24V controller from Adaptek India, Adyar for Rs 13600 with 3 years warranty.
  5. Structure Fabrication: This is the messy part of the entire exercise as readymade units were not available.  Since I will be using 8 panels in total and I had to use just 100 sq.ft of space on the roof, I planned to build a two row beam structure to take the load.  The weight of a panel is roughly 10kg, to 40kgs per structure is the setting.  The design shall have a rectangular frame of size 10’x3′ made out of 1.5″ L section of steel.  The rectangular section shall be supported by two 2″x1″ C channel steel of height 1.5′, which I call the legs.  The legs shall rest on a 8″x8″ 6mm plate, which in turn shall be secured to the roof with four 10mm anchor-flush bolts.  I could get raw material and fabrication done in Mannurpet, Ambattur for Rs 8000.  The total weight of steel I had installed is about 50Kg to keep the 70Kg of panel structure load secured.

Solar Power Plant Sizing chart is here.

More to continue..

Solar Panels Orientation for Chennai

December 21st, 2012 No comments
    Chennai’s Lat Lon value is 13° 04′ N 80° 17′ E and Earth’s axis is titled by 23.5°, so for Chennai the maximum Sun’s North-South swing angle is 10°N and 36.5°S.  If you setup the solar panel parallel to the ground, you would see the inclination angle of Sun at 12 noon would be a maximum of 10° to the north during Utthrayanam and a maximum of 36.5° to the south during Dakshinayanam.  So, for stationary solar panel fitments, the panel should be oriented to 13.5° to the south to have an uniform Sun’s inclination angle swing (+23.5° to -23.5°) relative to the solar panel reference line.

Solar Battery Charger Cutoff Circuit

August 7th, 2011 4 comments

Using very few components, I have built a solar battery charger cutoff circuitry that would enable automatic cutoff of battery charging when the potential across the battery terminals reached a voltage level chosen by the preset setting in the circuit.  Medium power transistor is operated in Cutoff mode most of the time, so the quotient current of the circuit is fairly low in the order of few mA.  It should be noted that the Vopen-circuit of the solar panel is few volts higher than the voltage when the panel is connected across a load.  So, don’t adjust the preset without connecting the battery. When the circuit is turned on, the battery is directly connected with the solar panel, and hence the voltage perceived by the voltage divider is the load voltage.  When the voltage across the load goes beyond the set point, zener conducts to turn the transistor on, which would pull the relay down and break the charging circuit.  After the battery is disconnected, the voltage perceived by the potential divider circuit is the open-circuit voltage of the panel, which eventually creates a latch effect for the battery charger off condition.  The relay will be ON, till there is sun light and when in the dusk, the input voltage should drop below the threshold voltage to turn off the transistor.

There is a flaw in this circuit. 🙂

When the sun light drops, the relay turns off as the transistor is turned off.  But now, the battery potential will be again available across the potential divider circuit.   There is a potential, oscillation condition here!!

Solar Panel Structure Design

July 17th, 2011 No comments

This was the original design of the solar panel mounting structure.  Later, I had simplified the design and fabricated them at the local metal fabricators.  Please click on the images to open the big sized drawing.

Pole that would hold the weight of a heavy solar panel over a base structure (not shown).

Hinge design that would transfer the weight from the base structure to the pole, with one degree of freedom.