Micro-Climates and Solar Output

Why do neighbours' solar panels perform differently?

Why your neighbour's identical system outperforms yours — micro-climate factors: (1) ALTITUDE: Every 100m elevation = 0.6°C cooler = panels 0.3% more efficient (cooler = better). But also more cloud. Net: marginal. (2) LOCAL SHADING: Trees, buildings, hills cast shadows at different times. Even slight morning shade reduces total output 5-10%. (3) URBAN HEAT ISLAND: City centres are 1-3°C warmer than suburbs. Warmer panels = slightly lower efficiency (0.3-0.5%/°C). Net: city panels 1-3% less efficient but more sunshine hours (less fog). (4) FOG VALLEYS: River valleys and low-lying areas experience more fog, reducing output 3-8% vs hilltop locations. (5) COASTAL EFFECT: Coastal areas often have more sunshine than inland at the same latitude (less fog, sea breeze clears cloud). TOTAL VARIATION: Micro-climate effects can cause 10-20% output difference between systems in the same postcode. Your installer's shading analysis accounts for site-specific factors. Source: PVGIS, Met Office micro-climate data.