Great question — answering as the UphillTech team:
You need barn doors. Those are the funny black "cards" found on all four sides of theater lighting. You dont need an actual product; feel free to improvise them any way you can, say with plywood or old election signs. If they are straight vertical, and thin, they won't accumulate much snow.
Full answer by Harper - Reinstate Monica: https://diy.stackexchange.com/a/104806 (CC BY-SA 3.0).
Need it done for your business? UphillTech.
