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Hydroponics Spinach NFT System

This post is to describe one particular system that – spinach using Nutrient Film Technique (NFT). An NFT system consists of a pipe through which a nutrient solution is circulated. Holes are drilled in the top side of the pipe and net pots containing the plants are placed in it. The water level in the pipe is adjusted such that the net pot just touches the water solution. A reservoir stores the nutrient solution and a submersible pump circulates the nutrient solution throughout the system to oxygenate the solution and also supply nutrients.


Spinach in Hydroponics NFT system

Hydroponics spinach NFT system – growing amaranthus, palak keerai, ponnangani keerai.

Here are the things that were used:

Total Bill of Materials – Rs.4000 approx, excluding the pH meter and TDS meter which costs another Rs.2500 and is common for all systems.

Also, a drilling machine with appropriate hole saw set was used to drill holes.

The big 6 inch PVC pipe was clamped to the wall in a slightly slanted manner to make water flow. One end received input from the nutrient reservoir and the other end was connected to the a slightly slanted ¾ inch return pipe(PVC) that was connected back to the reservoir to return the nutrient solution. The 6” PVC pipe had holed drilled on top to place net pots with plants on it. I hired a plumber to do the job according to my requirements.


Setting up the system: Pipe clamped to wall, holes for placing net pots drilled drilled. Below is another NFT sytem described in one of the previous posts

Setting up the system: Pipe clamped to wall, holes for placing net pots drilled drilled. Below is another NFT sytem described in one of the previous posts











End connector and Elbow joints for return pipe

End connector and Elbow joints for return pipe












The plants were germinated in cocopeat germination plugs and placed in netpots, which were in turn placed in holes drilled in the PVC pipe. The connector in the end cap was drilled such that the water level just touched the netpots. If too much of the netpot is submerged, then roots might decay and plants die. The submersible pump present in the 50 liter nutrient reservoir tank pumped water in the big pipe, which then flowed through the pipe and drained via the smaller pipe below into the reservoir. This is a critical thing, not just for supplying nutrients, but mainly for oxygenation of water. Roots need oxygen, else they will decay and plants will die. The nutrient concentration used was 400ppm initially and when the plants grew, the concentration was increased to 800ppm. The pH of the solution was maintained between 5.5-6.5. The water/nutrient topping up is done once every week.

I grew palak spinach, amaranthus and ponnangani keerai. This was the system in the first week:

System in the first week. The plant in the right is ponnangani keerai. In the left is palak spinach

System in the first week. The plant in the right is ponnangani keerai. In the left is palak spinach












However, these were windy months(june-july) and most of the initial plants except ponnangani keerai were broken down due to high winds. I replaced them all with new plants. The winds subsided after the month of august and now there’s healthy growth. The root health was average, with partially rotten roots, but enough healthy roots for the plant to grow. Below is the state of the system after 2 months:

1 2








After 2 months





















The problem with this system is that it does not have much direct sunlight as it is shadowed by the beam of the building. It has good indirect sunlight and that seems enough to have a healthy growth. We harvest from this system few times per month. Perhaps another system with more sunlight can increase the production.

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Hydroponics Spinach NFT System by Solarii Knight Anand is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Dabbling in Hydroponics

I have been meaning to write about my hydroponic system for a long time. Its Sunday now and there is lot of pending work for Monday at college, but nevertheless I have postponed long enough. My interest in hydroponics was sparked by my brother who bought a kit and attempted to grow spinach. I continued his efforts.

Hydroponics is a soiless method of growing plants using mineral nutrient solutions. Plants require these major nutrients – nitrogen, calcium, potassium, phosphorus, sulfur and magnesium and the following micronutrients in trace quantities– iron, molybdenum, manganese, copper, boron, zinc and sodium. In hydroponic system, they are fed in the form of salts like calcium nitrate, potassium phosphate etc. In soil microorganisms breakdown organic matter into these salts, while in hydroponics and fertilizer based agriculture, we provide the salts directly in optimal concentration. Also, the nutrient temperature, pH of the nutrient solution, oxygen levels of the solution(for root respiration) are controlled. Finding the right balance to get high yields is the challenge. There are many hydroponics systems. I tried Deepwater culture, Nutrient Film Technique(NFT) system and Kratky system. I am going to give an overview here and detailed blog posts on individual systems later. Four essential things are required to control the system – Total Dissolved Solids Meter(TDS) to measure the nutrient solution concentration, pH Meter, pH up(potassium hydroxide) and pH down(phosphoric acid).


Deepwater culture

This involves immersing plants in a tub containing nutrient solution. The nutrient solution is aerated by means of air pump which is used for fish tanks. The plants are placed in net pots which are placed in holes drilled in the tub. They were exposed to 4-5 hours of sunlight. The plants that I grew are eggplant and palak spinach.


DWC - rootsDeepwater Culture system

My initial aim was to get the plants to survive and grow in the hydroponic system and then think about getting fruits. The plants managed to grow, although the roots weren’t 100% healthy and has pythium root rot. Some plants died too. It wilts during peak sun initially and the temperature rises to 32OC. I kept the nutrient solution concentration at 800ppm and pH was maintained between 5.5-6.5 by using phosphoric acid or potassium hydroxide whenever necessary. I covered the tub with gift wrapper to avoid light from entering the tub and resulting in algal growth. The hydroponic solution I used first was called as ‘grow’ solution which had lot more nitrogen than phosphorus or calcium. Later as the eggplant plant bloomed, I used the ‘bloom’ solution. It has less nitrogen compared to potassium and phosphorus. However, the growth of spinach slowed due to bloom solution as it contained lesser nitrogen then grow solution. I had wanted to grow only spinach, but then later changed my mind and tried to test two plants at once.

The nutrient solutions were bought from The eggplant finally gave fruit and I got a bunch of leaves from spinach.




Nutrient Film Technique

This one consists of 3” PVC tubes with water circulating in them. Holes are drilled in the PVC tubes and netpots placed in them. Nutrient solution is filled in a big container. A submersible pump placed in the container circulated the nutrient solution through the system. The circulation keeps the solution oxygenated so that roots can respire. In this system, I threw in a lot of plants – eggplant, palak spinach, amaranthus spinach, some flowering plants, rose and even sunflower.



All the plants were germinated separately in cocopeat plugs. This system started off disastrously with lot of spinach plants dying for some unknown reason. I replaced them with new plants which included eggplants and sunflower. Two of the four eggplants that I placed survived while remaining died due to poor root oxygenation. The water flowing in the PVC pipe probably had stagnant layers down in the tube, hence I added a spaghetti tube siphon to circulate the lower layers too. After this the eggplants showed some improvement. The sunflower was a big success, it didn’t seem to have any root issues and it grew and a I got a bouquet of sunflowers! Rose didn’t fare well though. The spinach was fairly okay, but when I shifted the system into bloom solution after the eggplant and sunflower started flowering, spinach didn’t grow very well and leaves were wrinkled looking. The nutrient concentration used was 800ppm during growing stage and 1100ppm when sunflower flowered and back to 800ppm after it finished. pH was maintained between 5.5-6.5 by using phosphoric acid and potassium hydroxide whenever necessary. The nutrient solution temperature touched as high has 34OC. Need to experiment and find plants that suit my environment.




Kratky System

Kratky system is one where the plants are immersed in water solution without any circulation or air pumping for aeration of root zone. In this system, I tried zucchini in a big 50 liter barrel. It was germinated in a cocopeat pod and then placed in a big orchid netpot and placed in the container. It grew well and the root health was perfect. Here are the pictures.




I tried to grow tomato in kratky system too, but it was not successful.

I hope you enjoyed this demonstration of my hydroponic system in pictures. I will be back with detailed info on each plant type and two other plants – bitter gourd and cucumber.


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Dabbling in Hydroponics by Solarii knight Anand is licensed under a Creative Commons Attribution 4.0 International License.

500W Solar System

Last year, I made a 100W solar system. The system was good enough in the end only to power up a 12W LED tube for 6 hours. Add to the fact I broke 40W out of the 100W because I didn’t mount it properly. So this year I decided to go big to power something significant, which happened to the LED lights at the reception in my mother’s hospital. My primary motivation for setting up a solar system has and will always be to combat Global Warming. Secondary motivation is that it’s fun to generate your own power.

I had already made LED lights for the hospital’s reception with the foresight of mixing that with a solar system. There were about 10 LED downlights totalling to 110W of which all lights had to remain powered on for 3-4 hours in the night and 2 LED downlights totalling to 18W had to remain powered on for the remaining 8-9 hours. Added to this is the 40W LED floodlight that remains in operation for 12 hours, taking the total energy requirement to 1080Wh of loads. I decided on 500W,24V system which generates approximately 2000Wh per day. The excess power compensates for inverter losses and previous dull days. Here are the panels, in my roof:

 Two 250W Panels (60 cell)

Two 250W Panels (60 cell)

I bought the 20A PWM phocos charge controller to charge batteries of 24V,150Ah that can store 3600Wh ideally, but practically only 2800Wh can be used. The batteries are Su-kam tall tubular make and turned out to be a bad choice as well as a bad product. Firstly, they only gave a capacity of 75Ah. I think it was due the fact that battery was 3 months out of the factory when I bought it and lead acid batteries may not survive without degradation for that long. Additionally it seems normal tubular batteries cannot survive solar application. Within 2 months, the battery regressed to 50Ah and I had to replace them. I ordered and bought 2 Nos of 150Ah Exide Solar tall tubular battery. This battery, which has the ability to go long periods in partial state of charge, has turned out good so far, though I haven’t pushed the battery to full discharge and see its capacity.

The inverter I chose initialy was 1500VA,24V su-kam shiny UPS and not a solar hybrid inverter as I wanted a separate charge controller. But this turned out to be a bad choice too, as the inverter has 36W of self consumption losses and more importantly it did not have no load shutdown feature, which means someone has to manually turn off the inverter whenever there is no load connected in the output. I looked for a new inverter. I didn’t want an inverter with bulky iron core transformer as it was heavy and decided to try a inverter with high frequency transformer. I bought 1KVA,780W Sinex Solar PCU by Electronet Systems from GoGreenSolutions. It turned out to be fair. This solar inverter (aka solar PCU) has an no load shutdown and automatic wakeup feature. It has an disappointing self consumption of 24W when in operation and 6W when on standby mode, but still better than the pervious one due to no load shutdown. It is light and weighs 4.5kg, unlike the previous one that weighed 16Kg. It has poor dynamic characteristics, but since the load is LED lights that have SMPS and my laptop which has SMPS too, it is not a problem. But my desktop which I rarely use turns off when I subject the inverter to a new load. The inverter has an good fan control that varies depending on load.

Sinex solar PCU and Exide Solar tubular battery

Sinex solar PCU and Exide Solar tubular battery

Now for the overall power consumption of the system. The total energy requirement is 1080Wh, but inverter efficiency is 90%, taking the consumption to 1188Wh. Additionally, the inverter has self consumption of 24W for 12 hours and 6W standby for 12 hours adding upto 1548Wh. The power generation during a sunny day is 2000Wh and hence there is a surplus of 450Wh that can be used to compensate for dull days. The battery has a Depth of Discharge rate of 45% (1548Wh of 3600Wh) and manufacturer Exide claims that it can last for 3000 cycles(8.21years) at this Depth of Discharge.

The system serves well powering the reception lights of hospital. It is most useful during the time between power cut and when generator is turned on or when generator is down due to technical problems. The hospital does not remain in total blackout.

Economics of it

Two nos of 250W solar panels = Rs.27500

Charge controller = Rs. 3000

1KVA,24V Sinex Solar PCU(pure sine wave) = Rs.10200

Solar panel Mounting = Rs.4500

30m 4sqmm copper wire = Rs.1200

2Nos of 12V,150Ah Solar Tubular Battery = Rs.31600

sub-total = Rs.78,000


Su-kam Shiny HUPS = Rs.10000

2Nos of 12V,150Ah Su-kam Battery = Rs.30000

Grand Total = Rs.1,18,000

Overall the system cost is Rs.78,000. Generating 1.5 units per day and operating for 8 years with no failure, it translates to Rs.17.8 per unit (excluding cost of Investment). However, if I can find ways to reduce the cost of the system, especially by consuming the generated power instatnly, then I may have an answer to my mother’s hospital’s Diesel generator, which operates at 8-12 hours per day, producing power at Rs.20 per unit.

LED lights and Solar system mix

The use of LED lighting reduced the system size by 50%. Had I used CFL downlights and halogen floodlight, the system would have been atleast twice the size, costing an additional Rs.78,000. The cost incurred for the LED lights were Rs.23,000. So I realized that whem I’m generating my own power, every Watt hour of energy saved matters.

An audacious plan for the Future

I live in a state where power cuts are frequent and lasts upto 12 hours per day depending on the time of the year. Upto 50KWh is supplied for 12 hours by Diesel Generator. Currently the generator in my mother’s hospital produces power at the rate of Rs.20 per unit approx. That’s higher than what I acheived with my solar system. If I can make a big system that cuts costs then I might be able to bring down the cost of electricity supply while making the hospital contribute less to climate change.

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This web page by Solarii Knight Anand is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

My Experiments With Led Lighting 2: Downlights, Tubes and floodlight

After my last post, I have quite a few updates, which deserves a new separate post.

#1 For my home, it was strangely decided to buy LED downlights for general lighting(not for reading or work that requires concentration). I didn’t have knowledge of this and the downlights unfortunately was bought from a shop in Madurai with poor quality. In my experience in window shopping at Madurai for LED lamps earlier, I had found the lights to be of pathetic quality. Outraged, I demanded that all the lamps be first rectified and only then used. Below is a disassembled down light:

LED downlight - disassembled

LED downlight – disassembled

There were two problems – poor LED quality and low constant current driver output. The LED had a small die and poor luminous efficacy and the driver’s output was 160mA when it should be giving 350mA.

I bought many Edison Optronics 146 lumen 1W LEDs and drivers from Precious lighting Solutions in Ritchie street, Chennai. I found out that one of the 146 lumen LED was equivalent to 3 nos of the pathetic ones. For most of the lamps, I replaced three poor quality ones with one good quality one as the brightness was enough. Since I’m going to setup solar installation for my entire home, every watt of power saved is critical. I didn’t replace the driver for all downlights though. Downlight used for lighting staircase required high brightness and hence I replaced both there. For rest, I used the original driver and the one 146 lumen LED, which was enough. I don’t know how much was the cost of the original focus lamp was, but refitting a downlight cost me Rs.120 for the 3W constant current LED driver + Rs.150 for 3 LEDs, totaling Rs.270.

The problem I think is that most shopkeepers in Madurai didn’t know anything about LEDs and hence they were probably conned into buying it in the first place. Whereas, in Chennai, the shopkeeper is reasonably knowledgeable and hence knows what he is buying.

#2 I bought an 18W LED tube for Rs.1600. The total lumen output was mentioned as 1600 lumen by the shopkeeper. The brightness was considerably more than the 36W LED tubelight that I mentioned in earlier post. The light, though not spread 360 deg evenly like a FTL because the back side of it was made up of aluminum heat sink. But it was good enough, unlike my attempts to assemble tubes using short aluminium heat sink in earlier post. It was almost twice as bright as my other LED tube, which consumes 12W and cost Rs.1100. After this I spend a glut and bought 4 such LED tubes.


LED tube

18W LED tube

My brother didn’t like the LED tube as he feels that spending 40 times the amount of a normal tube (Rs.40 for T8 Fluorescent tube) for 50% decrease in power consumption is not economical, considering low domestic tariff. Also, LED technology is improving day by day and we’ll soon have better technology tomorrow. But I pointed out that since we’re going solar soon, decreasing the power consumption helps considerably as it reduces the size of the solar setup. But for commercial usage, it would require 16000 hours in operation to justify for the cost of LED tube over fluorescent tube at commercial rates. Also, I now feel that 15W(Rs.1300) from the same shop would have been enough as this is considerably brighter than a 36W FTL.

These tubes come with a one year warranty, but I do hope it lasts for 7-10 years.

#3 I assembled 4 LED 12W bulbs too recently. I used 146lumens/W LEDs to assemble. But before assembling, I read this concerning report about LED lights which says that blue light from LEDs can damage the eyes on the long run. The solution, apparently was to use warm white lights. Hence I assembled 12W LED bulbs using 9*1W cool white LEDs and 3*1W warm white LEDs. The light in the end had a yellowish tinge instead of a bluish one. The bulb is brighter than a 25W CFL. Though unlike a CFL or a FTL, the light is not very much distributed. Two of these bulbs will soon be operated at atleast 12 hours a day, thereby subjecting them heavy duty. It cost Rs.950 per bulb to assemble.

My calculations show that it will have be used at 12 hours per day for 3 years to be economically benificial at commercial rates of Rs.7/KWh over a 25W CFL. One problem was that only a Edison screw type base(E27) was available for the bulbs. These base cap holders are uncommon in India.

LED bulb raw -> finished

LED bulb raw -> finished

#4 From 1-Feb-13, I had switched on an 1W LED in order to possibly determine the durability and hence reliability of the LED drivers from Precious Lighting solutions. As of 14-july, the LED driver has operated successfully for 3900 hours. That translates to 2 years at 6 hours per day. Hopefully the driver will last much more than that.

#5 There is a 400W halogen in operation at my mother’s hospital and it needs to be replaced. To replace it, I would need 3*50W LED flood lights, according to a shop in Chennai. My calculations suggest that I’d save Rs.2375 for the first two years and Rs.15150 for four years. Here’s how

Capital cost:

For 150W LED – Rs.5800*3 = Rs.17400

For 400W halogen = Rs.7000

Difference: Rs.10400 more cost for LED flood light

Running cost for two years (assuming 10 hours per day at Rs.7 per unit)

For halogen: 0.4KWh*10hours*730days*Rs.7 = Rs.20440

For LED: 0.15KWh*10hours*730days*R.7 = Rs.7665

Difference: Rs.12775 more cost for halogen

Cost savings for first two years using LED = Rs.12775 – Rs.10400 = Rs.2375

Cost savings for next two years (assuming I don’t have to replace LED drivers which costs Rs.5000) = Rs.12775

Cost savings for four years total = Rs.15150

That’s much more than what a fixed deposit could give! Factor in rising power prices and usage of Diesel Generators for backup, the savings would be higher.

My college has been using LED streetlights, out of which 80% of them have never failed in my two years there. Hence the LED drivers can be deemed reliable for 2 years.. and hopefully the chance to fail in the 3rd and 4th years is also less as the quality seems good. Hence I’ll be buying it shortly.

More Buying tips:

1. Quality of LED products is critical. You don’t want to buy a LED driver that costs Rs.100 and that has to replaced ever few months or so. Also you don’t want to buy LEDs that are dimmer than CFLs. For people in South India, you can try asking from Precious Lighting solutions in Ritchie street. They are willing to ship. They assemble LEDs buy buying parts from Edison optronics. You can either get parts in non-assembled form to save some cost or get in assembled form if you don’t have time to solider. Shah infotech, another shop in Ritchie street is also an option, though their collection of products is lesser.

2. Buy from shops that know about the product they’re selling. If they don’t know stuff related to lighting like luminous efficacy, then most probably they’re conned themselves by merchants. For example my experience in Madurai revealed shops that knew absolutely nothing about the products and were of very inferior quality.

3. Cost of the LED lights at present is such that you’ll have to use it heavily to be economically beneficial.

I’ll probably merge the buying tips into one post later.

Environmental Impact:

The most important reason why I go for LEDs. But I’ll probably have to deal with this in more detail in a separate post. But anyhow..

1. Environmentally, LEDs have slightly reduced impact compared to CFLs, according to a 2012 report which compared a 60W incandescent bulb with 12.5W LED and 15W CFL. Today however, a 60W incandescent(12lumen/W) can be replaced with 7W LED bulb(110-150lumens/W), hence the gap would have widened. Also in recessed lighting, LED requirements will be a third to half that of CFLs and the footprint will be reduced considerably in that case. By 2017 LEDs will be much better off, as the technology is exponentially improving while Fluorescent technology has saturated.

2. Energy Star, an US government certifying organization has a list of certified products (both LED and CFL) which can be used for reference for buying. Here’s the pdf

That’s it for now. Will be back with an update on the Floodlight later in a few months.

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My experiments with LED lighting

I’ve been experimenting with LED lights for quite sometime now. Every time I try to put up a blog post, I hit the error “not enough data”. Then I realized that there can never be enough data. So I’ll just give information on my experiences so far.

LED lights have been used as indicators and traffic lights in the past. They are point sources of light that are visible from long distances, but was never enough to give light like a florescent tubes – until about 10-15 years ago. In the recent times, the cost has been decreasing for high power LEDs, making it affordable(though not economical yet).

Firstly, I tried high power LEDs by buying a few 1W LEDs and experimenting with them. A 1W LED cost Rs.60 approximately. The trouble was finding a good quality one. The LED lights that I bought were slightly better than CFLs of same power, but not enough to complete with a tube light. After much trial and error, I found LEDs of welly Power optronics corporation very good. I used the LEDs effectively to setup a light for my mother’s hospital reception. As shown in the photo shot, the LEDs were put inside a CFL enclosure. The results were outstanding. The LEDs managed to replace CFLs of twice its power. I made 10 such enclosures that is currently lighting up my mother’s hospital reception. Eight enclosures contain 8 LEDs each and two enclosures contain 12 LEDs. They are connected in series to a converter. Below are the screen shots.

Two 1W LEDs

Two 1W LEDs

LEDs soldiered and wired into CFL reflector

LEDs soldiered and wired into CFL reflector

LED in enclosure with constant current

The experiment with reception was good, though quite expensive – the enclosures cost Rs.9000. The 88 LEDs+PCBs used cost another Rs.4400 and converters Rs.4000. Wires and soldiering another Rs.500, adding upto Rs.17900. The enclosures originally meant for CFLs had copper ballasts and were wasted. It would have cost Rs.5000 lesser had it been not for those ballasts. Power wise it was a big gain though. t was 110W of LED instead of 240W of CFL in enclosures or 300W of tube light(tube lights fare poorly when directional light is needed). The constant current drivers that was used cost Rs.400 per piece and has a warranty of 1 year. It will be the deciding factor on how good my experiment is. If it lasts for 10 years then it would reach breakeven and there after it will be economical(building planners actually think that much ahead).

So, are LEDs a big gain over CFLs and florescent tubes? Well, it depends on the situation. For the hospital reception LEDs clicked because of a property of LEDs – they are directional and give light straight down, while in case of CFLs and florescent tubes they spread evenly all over the place. Enclosures need to give light straight down and hence LEDs worked really well. In case of home lighting, it is a different story. Florescent tubes give the same amount of Light 360o. It beats CFL lights by a league. I’ve tried using a 20W LED tube bought from ebay and a 20W LED light assembled by from a tube like enclosure. The 20W LED tube from ebay was of modest price (and probably quality too). The tube was unbranded and half the price of a usual LED tube. I found from my luxmeter it gave an overall light that is 70% of a 36W tube at 50% of a 36W tube’s power. Since LED lights are directional, it did not spread light 360o like a normal florescent tube, thus the room was dark in places where the LED tube did not face directly. But it was okay overall, and to my eyes it was as good as the 36W tube I compared with. The 20W tube like enclosure made from welly power LEDs(see the 20W one below; also I made 10W ones) gave light equal to a 36W tube. However, it was poorer in spreading light than compared to the other tube and it left the places that did not directly face dark. Especially the region behind it. Also, since the tube was much shorter and since I used two rows of 10W enclosures, it created distinct shadows unlike a tube light. Hence it gave an overall unsatisfactory feeling to the eye and one needs to adapt mentally to it.

tube enclosure - lighted

10W LED light

tube enclosure - off

10W LED light

20W LED light

20W LED light

The cost of the modest quality LED tube was Rs.1100(the ones available in the market varies between 1600-3000INR), while the cost of 20W setup was Rs.2000 approximately(18 LEDs, 20W adapter, 2 enclosures). The LED tube has been in operation at my home for about an year now. Everyone at home fits it comfortable enough for all purposes. I’m going to buy an better quality LED tube and see how it performs.

I also tested LED bulbs against CFLs. I bought a 9W Edison LED bulb and tested it against a 25W HPL CFL. The LED bulb didn’t turn out good as it gave 54% of lumens at 36% of the electric power. Also it is very concentrated compared to CFL or fluorescent tube light, hence I’m leaving the idea of using LED bulbs for home. It is worth noting that the 36W fluorescent tube light was 4 times brighter than the 25W CFL.
Buying tips:

The brightness of an LED lighting can be determined by the lumen/watt or overall lumen of the bulb. A normal fluorescent tube light has about 60-80 lumen per watt and CFLs have about 40-50 lumen per watt.
By the way, if any manufacturer says that LEDs don’t generate heat, don’t believe him – LEDs convert only 10-20% of electricity to light. Rest is converted to heat. LEDs life time is determined by 2 things other than quality – its internal temperature and life of the constant current LED driver. Higher the temperature, lower the lifetime(50000 hours at 85oC internal temperature). The electronic adapter is also the weak link in a driver’s lifetime. It depends on quality. The drivers that I get come with an 1 year replacement warranty.. I got a driver replaced after it failed under 3 weeks. None of the other 15 drivers that I bought have failed yet.

19-Feb-13: I bought a 6W LED bulb from ebay last week. It was as good as the 9W LED bulb that I mentioned earlier. It used 6 bridgelux 1W LEDs that gives 150 lumens/watt. It costs Rs.790+ Rs.100 for shipping and the seller has given a warranty for 2 years.

To conclude:

1. Buy carefully. Some LEDs are poorer than CFLs.

2. For recessed lightings used in showrooms, LEDs like the ones I used in my mother’s hospital should be considered. They are much better than CFLs.

3. For home lighting, LED tubes should be considered.


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