Solar equipment options for Washington, DC, Maryland, and Northern Virginia homeowners
Understanding solar equipment helps you compare installer quotes and choose a system that matches your property, budget, and goals.
Solar panel types
Monocrystalline: Made from a single silicon crystal. Higher efficiency (18–22%), better performance in low light, smaller footprint for the same output, and longer lifespan. Higher cost. Best for space-constrained roofs common in DC and Arlington.
Polycrystalline: Made from multiple silicon fragments. Lower efficiency (15–17%), larger footprint, lower cost. Less common in residential installations today as monocrystalline prices have dropped.
Thin-film: Lightweight and flexible but lower efficiency. Rarely used for residential rooftop systems. Occasionally used for flat commercial roofs or building-integrated applications.
Panel efficiency matters in the DMV because:
- DC rowhouses often have limited roof area
- Tree shading is common in established neighborhoods
- Higher efficiency means more production from the same roof space
Key panel specifications to compare
Efficiency rating: Percentage of sunlight converted to electricity. Higher is better, especially for space-constrained roofs.
Temperature coefficient: How much output drops as panels heat up. Lower (more negative) numbers mean better hot-weather performance. This matters for DMV summers.
Degradation rate: How much output declines each year. Premium panels degrade at 0.25–0.35% annually; budget panels at 0.5–0.8%.
Warranty: Most panels carry 25-year performance warranties and 10–12 year product warranties. Premium brands offer 25-year product warranties.
Inverter options
String inverter: One central inverter for the entire array. Lower cost, but the entire system operates at the level of the worst-performing panel. If one panel is shaded, all panels suffer.
Power optimizers: Devices attached to each panel that optimize output individually, with a central inverter. Better performance than string alone, especially with shading.
Microinverters: Small inverters attached to each panel. Each panel operates independently. Best for complex roofs with shading, but highest cost.
Inverter warranties range from 10–25 years. Microinverters and premium string inverters often have longer warranties.
Battery storage
Tesla Powerwall: 13.5 kWh capacity, integrated with Tesla solar systems. Popular but has had availability constraints.
Enphase IQ Battery: Modular system (3.36 kWh per unit), integrates with Enphase microinverters.
Generac PWRcell: Modular system with 8.6 kWh base capacity, expandable.
Battery considerations for the DMV:
- Backup power during summer storms and winter ice events
- Time-of-use rate optimization (if your utility offers time-varying rates)
- Additional cost: $10,000–$20,000+ depending on capacity
Roof considerations
Before installing solar, assess:
- Roof age and condition (solar panels last 25–30 years; your roof should too)
- Remaining roof life (if less than 10 years, consider replacing the roof first)
- Structural capacity (most roofs can handle solar, but older homes may need assessment)
- HOA rules (common in Northern Virginia and Montgomery County)
Flat roofs (common in DC rowhouses and some condos) require tilted racking or ballasted systems, which add complexity and cost.
How to compare equipment in quotes
Every quote should specify:
- Panel manufacturer, model, wattage, and quantity
- Inverter manufacturer, model, and type
- Battery manufacturer, model, and capacity (if applicable)
- Total system size in kW
- Estimated first-year production in kWh
- Warranty terms for all major components
Be wary of quotes that list "premium panels" without naming the manufacturer.
How Renovessa helps
The Renovessa solar planner helps you understand your roof's potential and what size system makes sense. When you request quotes through Renovessa, we help you compare equipment specifications across proposals.