Solar Street Light ROI Calculation for African Municipalities: A 10-Year Analysis

The True Cost of Grid-Connected Street Lighting in Africa

Grid-connected street lighting in African cities carries three major cost components: electricity consumption (typically 0.10–0.25 USD/kWh), maintenance (lamp replacement, ballast replacement, cable repairs), and the hidden cost of outages during load shedding or grid failures. In South Africa, where Eskom's tariffs have increased by an average of 15% annually since 2010, the electricity cost of a 150W HPS street light has grown from $45/year in 2010 to over $180/year in 2024.

10-Year Total Cost of Ownership Comparison

Cost Component	Grid-Connected 150W HPS	Solar 100W LED (All-in-One)
Initial Capital Cost	$350	$580
Annual Electricity Cost	$180 (escalating 10%/yr)	$0
10-Year Electricity Total	$2,865	$0
Maintenance (10 years)	$450	$120
Battery Replacement (yr 7)	N/A	$180
10-Year Total Cost	$3,665	$880

The solar option delivers a 76% reduction in 10-year total cost of ownership. The payback period — the point at which cumulative savings exceed the additional upfront cost — occurs at approximately 1.3 years for South African electricity tariffs.

Sensitivity Analysis: Key Variables

The ROI calculation is most sensitive to three variables: electricity tariff escalation rate, solar street light initial cost, and battery replacement cost. At a conservative 5% annual tariff increase (well below the South African average), the 10-year savings still exceed $1,800 per light. Even in countries with subsidised electricity at $0.05/kWh, solar street lights break even within 4–5 years.