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Complete 2025 Calculator & Planning Guide Location Impact is Massive: The same home using 1,000 kWh monthly could need just 16 panels in sunny Arizona but 22 panels in Massachusetts due to solar production ratios varying from 1.0 to 1.8 across different regions.
Part 2 of the solar lighting design guide is about determining the wattage and Lumen requirements of the project. This varies from fixture to fixture, manufacturer to manufacturer, and higher wattage does not always mean more light or higher lumen output. Each fixture has a standard LED wattage range.
Standard Efficiency Panels (350-400W) These panels represent the most budget-friendly solar options and work well for homes with ample roof space. Modern standard efficiency panels from quality manufacturers deliver reliable performance at lower upfront costs. For a typical 7 kW system, expect to need 18-20 panels in this category.
For a typical 7 kW system, expect to need 18-20 panels in this category. Standard efficiency panels are ideal if you have a large, unobstructed south-facing roof and want to prioritize lower installation costs over maximum power density. They'll deliver strong long-term performance and reliable energy production. High Efficiency Panels (400-450W)