The Solar Power Expert Blog

Solar Powered LED Grow Lights

by Chris - February 23rd, 2011.
Filed under: Projects, Solar Products. Tagged as: , , , .

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Although not a solar product per se, LED grow lights are an excellent load for solar power systems. In cold climates (like where I live) we have shortened growing seasons and many highly desirable plants like lemons, oranges, limes, kiwi, star fruit do not grow well here. The plants can be coaxed, but need to be given as much support in their early life as possible. A solar powered LED grow lamp can provide this extra energy they need to ensure good root development early in life as well as supplemental light during the fall, winter, and spring. I like to think of a solar powered LED grow light system as capturing non-usable sunlight, storing it, and reemitting it at my selected target.

Why do LED grow lights make such good solar powered loads? They are highly efficient and present a steady load to the system. These are both good qualities that make them optimal for a solar system. Below I will present quick coverage of the efficiencies inherent in solar powered LED grow light systems and then I’ll describe how to properly size a stand-alone solar power system for implementing a supplemental LED grow light.

Most people are aware that LED grow lights are efficient, but most people are not aware of the several ways in which they are efficient. Let’s explore each one:

LED Efficiency
This is the most widely known aspect of efficiency when it comes to LED grow lights. The general public has pretty much grasped that LEDs are a new and extremely efficient for of lighting. How efficient? Some LED clusters are able to operate at 90% efficiency. Compare that to an incandescent bulb which operates at about 5% efficiency. This means that LED grow lights are approximately 75% more efficient that a HID grow light.

Spectrum Efficiency
Plants do not absorb all colors evenly. In fact, the two types of chlorophyll in plants (chlorophyll a and chlorophyll b) absorb most light in the blue and red areas of the visible light spectrums. Newer, high efficiency LED grow lights will be composed of blue, red, and orange LEDs in order emit only those frequencies of light that plants absorb most readily. This improves efficiency because less light is needed to get optimal effect. Effectively it improves the efficiency of converting electricity to plant growth. Here is a picture of absorption of chlorophyll relative to the different colors of light:

Optimal LED Grow Light Emission

Long Life
Another advantage of using LED grow lights over other types of grow light is the long life inherent in LED technology. Heat is the killer of all lighting methods. LEDs high efficiency means they emit much less heat. A good LED grow light is often quoted as having a lifespan of 10 to 15 years. In actually, LED grow light technology has not been around that long so no one actually knows. The fact is that LEDs can last indefinitely. This effectively makes the LED grow light the most economical grow light because the cost of the bulb averaged out over its lifetime means it only costs a few cents per year.

Implementing a Solar Powered LED Grow Light System
Ok, so you’re sold on LED grow lights. Now how do you go about implementing them in a solar powered system? The setup is going to be just like the one laid out in the solar power generator. At the end of the inverter, you’ll plug in the LED grow light on a timer. This will allow you to have solar led lights with timer control. I’m assuming that you’ll only be using a few, small wattage LED grow light bulbs like this 2-watt LED grow light:

This bulb uses approximately 2 watts. You may want to use a higher power bulb, but the math is the same. Let’s say you want to provide two hours of extra light in the mornings and two hours of light in the evening. This little amount can make a huge difference and can mean the difference between life and death to exotic plants. This means we will be using 4 hours times 2 watts which equals 8 watt-hours.

As a rule of thumb, you should multiply this number by two or three in order to compensate for inefficiencies in the system. So worst case, we need our solar panel to generate 3 x 8 watt-hours = 24 watt-hours per day. This is where the magic of a solar power system comes in. If your solar panel generates 24 watts in one hour then you’re good to go. If it generates an average of 3 watts over an 8 hour period, that still makes 24 watts and you’re still good. As long as your solar power generator system can store that much energy during the daylight, you can successfully power your LED grow light. Of course, you don’t need to buy a solar power generator system. As suggested in the post, you can build one yourself out of the subcomponents (solar panel, charge controller, batteries, and inverter).

8 Responses to Solar Powered LED Grow Lights

  1. This little amount can make a huge difference and can mean the difference between life and death to exotic plants.

  2. It makes the most economical grow light

  3. It is the same idea as I often mention,using the solar energy and wind energy to drive the LED grow lights,everything comes from nature,and returns to nature,only in this way can we save our fuels and planet.

  4. LED grow lights are an excellent load for solar power systems, The plants can be coaxed, necessary to give support in their early life as possible. LED grow lights are efficient, but most people are not aware of the several ways in which they are efficient.
    LED Grow Lights

  5. 120w CFL v 7w led bulbs

    I need 3 bulbs 2 red 1 blue both bulbs cost 15$ each which should i go for

    I have no expirince with grow bulbs but i need somthing cheep to run I plan on using solar power

  6. Hmm… that’s a good question. I’m more of an expert in regard to the electrical side of things. I suggest looking at the ratio that UFO LED lights use.

  7. Good job.. Hope more and more growers change their traditioanl HPS,HID and MH grow lights. Saving more energy.

  8. Why invert to AC and then convert from AC to DC for the LEDs? LEDs are 12v. Would be possible to go directly to the LEDs from the battery and gain even more efficiency?

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