The True Math Behind Outdoor Lighting and Solar Energy

Sit down with your last power bill. Find the “price per kWh.” Mine’s $0.18. Now walk outside and count every outdoor light bulb. My old setup: two 60W floods (4 hrs/night), six 7W path lights (6 hrs). That’s 132Wh daily, or 0.132 kWh. Daily cost: 2.3 cents. Monthly: 70 cents. Annual: $8.40.

The solar system I nearly bought cost $450. At $8.40/year savings, the payback period is 53 years. The lights will be landfill long before then. That’s bad math.

Here’s the real math: I wasn’t running those lights because they cost money. I’d turn them off to “save.” With solar, I run them dusk-to-dawn, every night. The value isn’t in replacing existing cost—it’s in getting light where you currently have darkness. Put a dollar value on your family not tripping on the path. On your house looking occupied on vacation. On enjoying your patio after sunset. That’s the return on investment no bill shows.