We've been quite busy past 1 year building something quite exciting! We are hoping it will change the world :)
Solar Pumping can play a critical role in enhancing livelihood of the farmer. In absence of good reliable power, Solar can be the missing link between hardwork and prosperity for the farmer.
We visited a village called Kinhawali in Palghar district of Maharashtra for Solar Pumping System without batteries to enable the tribals to farm throughout the year. Water will be pumped into a artificial tank and then used for farming even when power is not available. Power can be missing for weeks altogether when lines are down due to damage.
NOTE: Click here if you can't view the ppt:
A lot of customers ask us how to install clips for LED Panel Lights. Sometimes, if they are not installed properly, the light may come loose, creating the impression that the clip is defective or of poor quality. This video shows the proper way of attaching clips to the light:
Here's an alternate technique I found on youtube:
This article will walk you through repairing an LED Street Light. You can follow this procedure to repair hand soldered LEDs.
Basics of a Light
Every LED Light has 2 essential electronic components:
1. LED Driver: This power supply converts 230V AC to DC power required for LEDs.
2. LED Diode or LED: This stands for Light Emitting Diode. This is the main component that emits light when electricity passes through it. These come in several types. The ones that can be easily repaired come in Lambardian package, which can be hand soldered.
A light can stop working mainly for 2 reasons:
1. Damaged LED Driver: When this happens, the entire light either stops working completely OR all LEDs glow partially.
2. Damaged LEDs: When this happens, you will notice a row of LEDs not working. Alternately, you will see LEDs flashing, i.e. coming ON and OFF quickly. You may also notice some LEDs to have gone black.
In this article, we will discuss replacing damaged LEDs.
Soldering Iron and Solder Wire
Step 1: Lay the light upside down on a flat surface.
Step 2: Unscrew 4 screws that keep the glass attached to the casing.
Keep the 4 clamps aside carefully.
Step 4: Gently lift the light to remove glass. If it does not come off easily, try to take it off by gently knocking on the casing from behind, or using a screw driver. Keep the glass and the silicone lining aside.
Step 5: Rotate the light right side up with the glass removed.
Step 6: Each LED has a positive (+ve) and negative (-ve) terminal. The -ve terminal is marked with a hole on the negative side.
Step 7: The PCB has a clear marking for how the LED should be placed on the PCB.
Step 8: We will use the Multi-meter to locate the damaged LED. Set the Multi-Meter on Diode testing mode.
Step 9: Start testing LEDs by touching the +ve wire (red) to +ve terminal of the LED, and -ve wire (black) to -ve terminal.
If the LED glows, it means the LED is OK.
If the LED does not glow, it means the LED is damaged. Mark this LED with a marker.
Test all LEDs in this fashion.
Step 10: For all the damaged LEDs, remove them using a soldering iron.
Step 11: Solder the new LEDs in place of removed LEDs making sure the +ve and -ve terminals are matched properly.
Step 12: Test the light carefully without touching inside of the light. Check if light is working properly. If it still does not work like before, and you are sure all LEDs are OK, then it's a problem with the Driver. Get in touch with the manufacturer/dealer to get a new matching driver.
Step 13: Next place the silcone lining in its grooves.
Step 14: Place the glass into the casing.
Step 15: Turn the light around holding the glass in place, and start attaching the clamps.
Step 16: Turn casing side ways to tighten further.
Step 17: You light is now as good as new!
Thank you for reading! Please do not hesitate to ask questions or leave comments below!
We spent this weekend installing a 200W solar panel to power some of the AC loads in my home. Instead of the traditional method of using a panel to charge batteries, I installed something called as a Grid-Tie Micro-Inverter. Like most things in life, this has advantages as well as disadvantages. Read on to find out more...
What is a Micro-Inverter and what is it used for?
There are generally 2 ways of harvesting energy of the sun. In the more common method adapted for residential applications, you connect Solar Panels to a Battery Bank via a Solar Controller, and use the energy stored in the Battery Bank using an Inverter to run your AC loads like lights, fans, etc. Dis-advantage of this technique is the Batteries, which are costly and need replacing in 4-5 years. However, when you have access to fairly reliable grid electricity but would still like to use Solar Energy without incurring cost of batteries, Micro-Inverters is the way to go. A Micro-Inverter connects directly to your Solar Panel and generates AC power that's phase matched with your grid power. Thus, your appliances use what ever power is generated from your panels, and the balance power is drawn from the grid, thus eliminating the need of batteries, and reducing your electricity bill. Since one Micro-Inverter is connected to one panel, it can utilize something called as MPPT (Maximum Power Point Tracking) to extract maximum power out of a solar panel, which is not possible in systems where multiple Solar panels are connected in series/parallel to a single Inverter. Another advantage of a Micro-Inverter is that it can be connected to additional Micro-Inverters in a daisy chain to add capacitiy to your system, letting you increase capacity of your system gradually. Since each Micro-Inverter directly generates 230V AC from the panel its connected to, you can even connect mis-matched panels of different make, capacity, and age, which is not possible in traditional systems. The term "Grid Tie" implies that it's directly connected to the Grid supply, and supplies excess power back to the grid.
Does a Micro-Inverter generate power if the main power goes down?
A Micro-Inverter will stop generating power if the main power is shut off. This protects an electrician working on the line after he's shut off the main supply.
What if you generate more power than you use?
Here's the unfortunate part in a state like Maharashtra. The state has not introduced legislation to support Net Meters, where the electricity company can give you a rebate for whatever excess electricity is generated. Today, if you generate more than you use, the normal meter will report that as energy used and you will end up paying for the excess energy you produce! Therefore, you need to be careful in sizing the system to be just under what you normally use.
Will a Micro-Inverter supply power on a branch circuit that's being supplied power from a Diesel Generator OR a regular AC Inverter?
It would be great if you could supplement you Inverter/Diesel Generator's power in case of an outage to save Diesel/Battery. However in most cases, the Micro-Inverter is not able to synchronize the wave-forms generated by these power backup systems and shuts down till main power comes on. This means that your Micro-Inverter won't generate any power when your home is running on backup power. So one usually ends up connecting a Micro-Inverter on the input side of these systems rather than output. Having said this, I have personally not tried it out, and would like to confirm for myself that that is indeed the case.
Are Micro-Inverters cheap?
Sadly no. These devices are fairly sophisticated. Cost per watt for these will be almost the same as what you pay for the panel. But their inherent advantages make them worthwhile in the long run.
Photo our our Installation:
First step of making a Solar Panel starts with cutting a Solar Cell. Check out our following video that explores this first step..
What is a Solar Home Lighting System (SHLS)?
A SHLS is typically a Battery powered system that is charged using a Solar Panel. The energy stored in the battery is then used to illuminate one/more rooms of your home or shop or classroom. These systems can also offer mobile phone charging and the ability to charge the battery using AC wall socket.
Uses of a Solar Home Lighting System
India of the 21st century, sadly, has not been able to satisfy basic power requirement for all of its citizens. Till that happens, a SHLS can provide a good alternative to satisfying needs of homes/shops so that businesses can run & kids can study well past sunset. A SHLS can be used in places that either do not have reliable 24 hours grid electricity OR no grid electricity at all. It can also be useful for people on the move like soldiers, campers, and small vendors. Furthermore, with mobile phones becoming a basic necessity for all; a SHLS can provide that essential ability to charge a mobile device even when there's no access to AC power.
Types of Solar Home Lighting Systems
SHLSs can come in all shapes and sizes. These range from the very small Solar Key Chains giving a couple of hours of light to the off-grid Solar AC Inverter which enables you to run all your AC Loads like Lights, TV, Fans, Mixer, etc for several hours all together.
Following are common types of Solar Home Lighting Systems:
Solar LED Torch Key-Chain
This is the lowest in the food chain of solar lights and falls under the category of a novelty item. It has a very small solar panel, a tiny battery, and a very low power LED light, all of which can fit on a key-chain. It can come handy as a low power torch and charges on ambient light. These, however, do not last very long as the battery usually is of fairly inferior quality to keep the cost low.
Solar Lamp / Solar Light / Solar Light Bulb
A solar lamp typically offers a small LED light (0.2 to 1W) powered by a re-chargeable cell (NiCd, NiMH, or LiIon/LiPolymer/LiFePO4). A small Solar Panel (usually about 0.5W or less) is attached directly to the body of the lamp that enables you to charge the light during day time. Such a lamp provides 3-5 hours of light and can sometimes also have a mode that lets you adjust the brightness to extend the battery life. The illumination offered by such a lamp is usually sufficient for tasks like studying/cooking but will not illuminate the entire room. These usually do not offer mobile charging as the battery is of a limited capacity. A good brand will use a Lithium Ion (or similar) cell that can last for more than 1000 charge cycles. One disadvantage however can be the general availability of an appropriate Li Ion cell and the cost of replacing such a cell.
Solar Lantern / Solar Emergency Light
A solar lantern looks like a kerosene lantern and provides uniform illumination all around. These are usually made of several (20-40 nos) low power LEDs, and are typically powered using 6V Sealed Maintenance Free (SMF) Lead Acid Batteries. The Lead Acid battery will have a shorter life (around 1 year), but can be easily replaced. Good brands like Luminous/Excide/Amaron generally do not make 6V batteries, so one is at the mercy of cheap Chinese brands. Few solar lanterns can also offer you mobile charging, but it's usually not sufficient for charging smart phones that consume more power. Solar Panels for these lights are usually separate, and come with a long wire so that you can place the panel in the Sun and the lantern indoors. This is important because heat tends to reduce the life of a battery, and you can get better performance form your solar light by keeping it away from heat and sun.
Solar CFL Inverter / Solar LED Lighting System / Solar Home Lighting System
Such a system has a bigger Lead Acid battery (12V 7.2Ah) commonly found in small UPS systems and easily available in local battery stores for about Rs.700. This system supports one/more CFL lights OR one/more LED lights with optional mobile charging. CFL systems, which you might have seen with some vegetable vendors, require more power and therefore give lesser backup. In CFL systems, the battery also wears out sooner. LED systems are better because of the long life of LED bulbs and they consume less than half the power of CFLs. Like Solar Lanterns, these systems have a separate Solar Panel usually 10 to 15W in power that charges the battery in 8-10 hours. Some systems will also provide AC charging. Typical backup for CFL systems is about 4 hours for 2 11W CFL lamps, while it can be 10-12 hours for 2 LED bulbs of 5W. Green Pyramid Solar is working on special techniques that extends total hours even further.
Solar AC Inverter / Solar Hybrid Inverter System / Solar PCU
This is the big daddy of SHLSs and runs your normal 230V AC loads like fans, mixers, CFL/LED Lights. These come in 2 flavours: Solar Off-Grid Inverter, and Solar Hybrid Inverter. A Solar Off-Grid inverter is suitable for homes with no access to grid electricity. These have Pure Sine Wave/Modified Sine Wave AC Inverters running off Inverter Batteries (100Ah - 200Ah) which are charged using Solar Panels. A Hybrid Inverter runs off the Battery as long it's fully charged. When the voltage of the battery falls under a specific level, the solar panel charges the batteries and the load switches to the grid. Hybrid Inverters help you reduce electricity bill providing you power backup at the same time when grid is not available. In these systems Solar Panels tend to be bigger, in the 100W to 200W range, and need to be properly installed to get most out of the system. These also require a higher upfront cost. Panels last more than 25 years but batteries have to be replaced 3-6 years, which should be factored into the cost of the overall system.
Lighting based on Solar Power is now available in several form factors. You can select the correct system based on your specific needs and price range. Several of these are also available online on websites like ebay.in, and amazon.in, which lets you compare prices and read customer feedback. Green Pyramid Solar has also introduced a range of these lights which we would love for you to check out!
Author's Note: If you have any further questions, feel free to add a comment to the Blog, and I will try my best answering those in a timely manner.
I know this post does not in any way relate to Solar or LEDs; however I spent a nail biting weekend trying to track down my UK visa. I finally figured out a way of tracking the passport, and thought if some other hapless traveler finds him/herself in my shoes, hopefully this post will help them. I had already received a mail from the consulate saying my Visa had been handed over to VFS 3 days ago. However, there was no communication from VFS about the delivery of my visa. I was going to fly out Sunday and it was already Saturday. I then chanced upon the following link. You can track your Passport from Blue Dart web site. Simply enter your application reference number in the Track your shipment section and select the Ref no option. It used to accept passport number earlier but that option has been changed recently to use the application number. Your application number is typically of the format: GWF012345689. Try entering the number part of your GWF number (E.g. 12345689) as the Ref no. If that does not work, enter the full thing, viz. GWF012345689.
The earlier method of tracking your VISA status by sending SMS to 57333 using format "VISA UK <passport number>" does not seem to work any more.
Why LED Street Lights
LED Street Lights are expected to revolutionize illumination of streets and common areas. They consume less than 15% electricity as compared to Incandescent lights, and have better life and light quality compared to High Intensity Discharge (HID) lamps like Sodium Vapour (HPS), Mercury Vapour (HBO), or Metal-halide lamps. LED Lights last at least 50,000 hours (13 years @ 12 hours use per day), and provide better control over the illuminated area reducing light pollution. Being solid state devices, they can be constructed in a robust fashion which reduces the risk of glass breakage during maintenance and operation. By switching to LED Street Lights, Municipalities/Institutions can save almost 30-40% of their budget costs which can be put to other good uses.
Why a _GOOD_ LED Street Light?
A badly constructed LED light can fail early, cause damage, or not function as per your requirements. LED Lights can require a higher upfront capital investment with a promise of lower long term running costs; that's why it's very important that you be able to reap the benefits of the long life of the LED Light. This post hopes to equip you with the right questions that you should ask your LED Light supplier to be able to choose a suitable product for your use.
Characteristics of a GOOD LED Street Light
Dust and Water Proof
Your light will be sitting outside exposed to elements. Therefore, the innards of your light (viz. the LED Chips, Driver, etc) must be adequately protected against moisture and dust. This protection is usually described using a rating system called the IP Code or the Ingress Protection code. To a minimum, your light fixture must be IP65 compliant. This means it has dust and water protection. If you stay close to coastal areas, also consider if the light is safe against the corrosive salty sea winds.
The single most important thing that determines the life of your LED in the temperature at which the LED operates. Life of LED means the duration for which the LED generates rated light output. LED which can last more than 50,000 hours at the rated temperature can rapidly reduce in life, say from 10 years to less than 2 years, if operated at a higher temperature. Therefore great care needs to be taken when constructing the LED Light to rapidly dissipate heat away from the fixture. LED Lights can employ either active and passive cooling. Most fixtures have a passive cooling mechanism where LEDs are mounted on Metal Core PCB (MCPCB) which in turn are attached to an Aluminium casing using a good thermal interface material. When selecting a LED light, it's important to choose one which has good thermal management. This can ensure full life of your LED Light.
Robust LED Driver
LEDs are DC devices. That means you need an electrical circuit to convert 230V AC from grid to a DC voltage. This electrical circuit is called a LED Driver. Since LED Street Lights can be installed at remote/rural areas with not-so-reliable-grid-voltages, the driver should be able to withstand sudden voltage surges induced by electrical interference like Lightning strikes OR be able to shutdown if voltage falls over or under an operating range. Good LED drivers typically operate between 150V to 270V with about 4KV surge protection. A good driver will also have a thermal shutdown mechanism that protects the LEDs in case of a malfunction that causes a lot of heat to get generated.
The drivers can come in 2 varieties: Isolated & Non-Isolated. Isolation is basically an electrical barrier between the input and output side, most commonly using a transformer. An Isolated driver protects the end user from an electrical shock and can also protect against reversed polarities. Isolated driver should be preferred over an non-isolated one.
LED can also get damaged due to an excessive current flowing through it above and over its rated value. Therefore, good LED Drivers are Constant Current devices (as against Constant Voltage), which keep the output current constant even if the output load changes due to changes in temperature. As LEDs get hot, their resistance tends to decrease, which can cause an increase in current. Also, not all LEDs have the same resistance. A constant current driver protects against all these conditions and keeps the same current flowing through the LEDs thereby protecting them and increasing their life.
Light emanating from a LED tends to be very directional. Therefore LEDs come attached with special Optics or Lenses that help it dissipate light over a wider area. The shape and the nature of the light coming out of the LED Light will be a topic of a separate blog but it suffices to say that selection of LEDs and Optics plays an important role in deciding how suitable the light is for your specific application. E.g. a light used for general illumination should spread its light over a wide area where as a light meant to illuminate roads should direct most of its light towards the road and very little away from it.
Light Intensity and Color
The total light coming out of a fixture is measured in Lumens, where as the the total light falling on a unit area is called LUX or luminous intensity. There are specific guidelines for LUX based on the nature of work. E.g. total LUX needed at a work desk in an office will be different than that needed on a side walk. When selecting a LED light, make sure that the light satisfies your LUX requirements when mounted at the specified height.
Another parameter is the Color of light produced by the LED. Most common colors are Cool White or Natural White which is closer to daylight. Some applications might prefer Warm white. Color is measured by something called Corelated Color Temperature (CCT) and its unit is degree Kelvin (K).
Yet another parameter is called the Color Rendering Index (CRI), which essentially indicates how accurately the light source can illuminate an object's true color. Yellow light has a very poor CRI where as a white CFL has better CRI. CRI can become very important if the light is to be used where accurate color reproduction is needed, e.g. a shop selling Sarees or Shirts. CRI over 70 is generally desired.
Like a lot of things in life, things are not as simple as they appear at first. Not all LED lights are created equal. A little information can go a long way in helping you select an appropriate LED Light for your specific application. Hope this article will help you with just that. Comments welcome!
Selecting a LED light