Low Energy Lights

Hello all. I'm new to this forum, have read lots of posts. I see there's an incredible amount of information here.
I am trying to put together a solar- or wind-powered system to run two lights on a flag that is 30 feet off the ground. Its located on top of a hill where there is lots of wind and I'm leaning towards using wind power. I am looking for some lights that would be comparable to 90 watt halogen 110volt, but that could be run off the DC power that would be produced by a 200 watt wind generator. I don't know of any LED that are strong enough. Maybe some metal halide. Any ideas?
I am considering using a "Chinook" brand wind generator. Does anyone have any experience with this kind? They are built in Montana in small quantities and are said to be very durable.


  • BB.BB. Super Moderators, Administrators Posts: 33,082 admin
    Re: Low Energy Lights

    Lights that run 12 hours a night are very tough to power off-grid in a cost effective manner.

    As a start, certainly the most efficient, smallest wattage that will meet the needs is a start.

    LED's--There is a lot of variability out there--and many LED's don't seem to last more than 500-1,000 hours (instead of the 50,000 hours usually listed on the box).

    A CFL flood might be a better choice.

    In any case, you need to pick your power needs. Say 2x13 watt for 12 hours per night:
    • 2*13 watts * 12 hours = 312 Watt*Hours per day
    A Chinook 200 watt turbine will (according to the little bit I found) generate 40 kWH per month at 12 MPH:
    • 40,000 watt*hours per month * 1/30 days per month * 1/24 hours per day = 55.6 Watt average output
    • 312 WH per day * 1/0.80 battery efficiency * 1/0.85 inverter eff * 1/55.6 watts generated = 8.3 hours per day of 12 mph+ wind
    If you have 12 MPH average winds at least 8.3 hours per day--Then you may have enough wind to power two 13 watt cfl lights on a flooded cell battery bank with a 120 VAC inverter (there are DC CFL's available, but they tend to be pretty expensive).

    For central Montana, using PV Watts, we see hours of sun per day as:
    "Station Identification"
    "Lat (deg N):", 47.05
    "Long (deg W):", 109.45
    "Elev (m): ", 1264
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 47.1"
    "Array Azimuth:","180.0"

    "Month", "Solar Radiation (kWh/m^2/day)"
    1, 2.95
    2, 3.84
    3, 4.95
    4, 5.04
    5, 5.49
    6, 5.91
    7, 6.44
    8, 6.26
    9, 5.52
    10, 4.68
    11, 3.07
    12, 2.72,
    "Year", 4.74
    Worst case sun is 2.72 hours of sun in December, assume 0.52 system efficiency (solar panel to AC inverter output):
    • 312 WH per day * 1/0.52 sys eff * 1/2.72 hours of sun = 221 watts of solar panels
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • MisterBMisterB Solar Expert Posts: 156 ✭✭
    Re: Low Energy Lights

    I would recomend you go solar for what you are proposing. Wind energy potential can look good from a distance but when you actually measure what you get from a site, it can be a lot less than it looks. And the cost of the wind generator is not the total cost of the system, the tower installation and maintenance of even a small wind turbine need to be taken into account. And if you are dealing with a constant load like a couple of lights, you take out the "human behavior" varible that you have to deal with in an off the grid home system and the math is a lot more straightforward. Solar is much more constant and reliable than wind and the seasonal variations in energy are much more easy to predict. It will probably be more cost effective in the long run to put in a solar system with enough extra watts to cover the December/January conditions than to deal with the hassle of a mechanical turbine.

    I am using an mixture of ultra low power LED lights, most of which I have made or modded myself, and halogen lights for my home lighting. The LEDs are great for low level ambient lighting but if I need to read or work on something, I use 10 watt halogen lights. The LED lights have a white spectra that is very much like moonlight while the halogen bulbs give out a very instense light that is very solar and they generate heat as well which is good on cool nights. They give you much more bang for the watt than incandescant bulbs. There is no way I could work with just one 15 watt incandescant bulb but 10 watts of halogen light is fine and 20 watts is really bright. The LED lights are very focused and will shine bright light on a very small area and a few feet away the light will be very dim while incandescant and halogen bulbs will flood a broad area with light.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Low Energy Lights

    I would be interested in a separate discussion regarding LED light. I've purchased them over the years but not with solar in mind, so my choices have been AC versions.

    In looking for low power, DC LEDs, I found that solar-powered holiday lights are probably the easiest to purchase, but are they practical? If I may post one link for an example, this seems easy enough to mod.


    Or is this too rinky-dink to bother with? Thanks
  • BB.BB. Super Moderators, Administrators Posts: 33,082 admin
    Re: Low Energy Lights

    For $11--Have fun playing with them and see what happens.

    If you want to see lots of detailed information on LED lighting--Take a look at this forum:


    Lots of very good information over there.

    Of course, you are welcome to start a thread here too.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Low Energy Lights

    Thanks for those web sites. I'll be calling them, since the product I'm interested in do not list any lumen ratings.
  • peterakopeterako Solar Expert Posts: 144 ✭✭
    Re: Low Energy Lights

    Hi there,
    In my house i amnearly only using LED lights all by european brands philps osram etc.. after two years use i do not have one failure or dimming age problems. i think pecause i use brands!!!!
    next month i will install 12 pcs 14W pure white light led modules.

    Greetings from Greece
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Low Energy Lights

    Does anyone have experience with the Star light brand of 12v leds?


    I saw these in my local rv supply for around $25 each, but they can be gotten off the net for about $18-20 each if bought in bulk.

    Are they worth the cash at 150 lumens?
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