electronics keralam : February 2013

Thursday, February 21, 2013

സോളാര്‍ ചാര്‍ജ്‌ കണ്‍ട്രോളര്‍ എങ്ങനെ കണക്റ്റ്‌ ചെയ്യണം

സോളാര്‍ ചാര്‍ജ്‌ കണ്‍ട്രോളര്‍
എങ്ങനെ കണക്റ്റ്‌ ചെയ്യണം

ഇന്‍വെര്‍ട്ടര്‍ ചിത്രത്തില്‍ കാണിച്ചിട്ടില്ല

Sunday, February 10, 2013

1KW Solar Power Plant

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.

സോളാര്‍ പവര്‍ പ്ലാന്റ് സൈസിംഗ് ചാര്‍ട്ട്

സീലിംഗ് ഫാനിന്റെ ഉള്ളുകള്ളികള്‍

സീലിംഗ് ഫാനിന്റെ ഉള്ളുകള്ളികള്‍

നിങ്ങള്‍ ഒരു ഫാന്‍ മോട്ടോര്‍ തുറന്നു നോക്കിയിട്ടുണ്ടോ? അത് ഒരു ലളിതമായ ബ്രഷ് ലെസ്‌ A/C ഇന്‍ഡക്ഷന്‍ മോട്ടോര്‍ ആണ് മോട്ടോറിന്റെ ഭാഗങ്ങള്‍ ചിത്രം നോക്കി മനസിലാക്കുക. പ്രധാന ഭാഗങ്ങള്‍. C: ബോള്‍ ബെയറിംഗ് D: സ്റ്റേറ്റര്‍ E: ആര്‍മേച്ചര്‍, G:കപ്പാസിറ്റര്‍, H: കണക്റ്റര്‍

Also, look at the other image that shows the cross section of a motor. You would notice that there are 4 wires coming out the motor. Two pairs of wire, with one pair as the starting coil and the another pair for the running coil. In general, all single phases induction motors have two coils (starting coil, running coil). Using a capacitor, an artificial phase difference is created between the fields created by the starting and running coils. The phase difference triggers movement of the armature. When the armature reaches a particular speed, using a centrifugal switch, the connection to the starting coil is disconnected and the entire fans runs with just one coil.

Although there are four terminals, you would notice 3 terminals are emitted out, with the starting and running coils connected back-to-back. Let’s say S1,S2 are the terminals of starting coil and R1,R2 are the terminals of the running coil. To get 3 terminals out of the fan motor, S2 and R2 are shorted.
Now, you just see 3 terminals; how do you find which terminal is starting, which one is ending and which one is shorted? Easy. Using a simple multimeter, you can find it out.
Let’s say you see terminals A, B, C. Our aim is to find which one of these are S1, R1, S2R2. Now, let’s measure the resistance between A-B, call it X. Likewise measure the resistance B-C as Y and A-C as Z. If you would notice X < Y < Z, you would also notice that Z = Y+X. Which mean, A-C is action A-B+B-C, that’s why the resistance was additive, also the terminal B is S2R2. The challenge now is to find what is A and what is C. As we’d notice A-B=X < B-C=Y, we can confirm that terminal A is starting coil S1 and terminal C is running coil R1. The reasoning is that; starting coil resistance will be less than running coil resistance.