electronics keralam : 1KW സോളാര്‍ പവര്‍ പ്ലാന്റ്

Sunday, February 10, 2013

1KW സോളാര്‍ പവര്‍ പ്ലാന്റ്

1KW Solar Power Plant

sudarsun.chennai

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:

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.
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.
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.
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.
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.