I have a 75 watt HP sodium light fixture placed high up on barn, which is aprox. 150 feet from house and it throws enough light to see your way around the whole yard. It operates from dusk to dawn on a sensor same as street lights. The light has a more orange / yellow cast which I am fine with, cheaper to operate than mercury vapor. The local power company has switched all street lighting to the same HP sodium, 2 reasons cheaper to operate and they also cut through fog better than mercury. We gets lots of fog. I have replaced 1 bulb in the 20 years of operation which cost me about $30 Canadian. The fixture was about $45-50 new. I am not sure of monthly cost, the barn is powered from house, but it does what I need so not concerned. It does need a few minutes to warm up to full brightness, but with the sensor it comes on when needed, so again has not been a problem. It operates 365 days a year in all weather and temperatures, winter / summer. We can get quite cold in winter and it has never failed to start. I have tried the CFL's inside barn and they can't compare, will not light in cold, light intensity low compared to halogen or sodium, and if they break release mercury. So a no go for me, and LED's are still to expensive for initial purchase, but real cheap to operate it wait and see on these.