Key Takeaways
- A solar array is the complete collection of panels in a PV system, wired in series and parallel strings
- Array sizing depends on energy consumption, available roof or ground area, and budget
- Panels within an array must be matched by type, wattage, and orientation for optimal performance
- Array layout directly impacts energy production, shading losses, and installation costs
- Residential arrays typically range from 4–12 kW; commercial arrays from 50 kW to several MW
- Proper array design accounts for structural loads, fire setbacks, and electrical code requirements
What Is a Solar Array?
A solar array is a group of solar panels (also called modules) mechanically mounted and electrically connected to form the power-generating component of a photovoltaic system. The array is the largest physical unit in a PV system — individual solar cells make up a panel, and multiple panels make up an array.
The term “array” refers specifically to the panel grouping, not the complete system. A full PV system also includes inverters, racking, wiring, disconnects, and monitoring equipment. But the array is where electricity generation begins.
A well-designed solar array balances three competing priorities: maximum energy production, structural integrity, and code compliance. The best arrays aren’t just big — they’re optimized for the specific site, load profile, and financial constraints of each project.
How Solar Arrays Are Configured
Solar arrays are organized into electrical groupings that determine voltage, current, and compatibility with the inverter. Here’s how the hierarchy works:
Solar Cells
Individual photovoltaic cells (typically 6–7 inches square) generate 0.5–0.7V each. A standard panel contains 60, 72, or 144 half-cut cells wired in series.
Solar Panels (Modules)
Cells are encapsulated in glass and a frame to form a panel. Each panel produces 350–600W depending on cell count and efficiency. Panels are the building blocks of the array.
Strings
Panels wired in series form a “string.” Series wiring adds voltages together while maintaining the same current. String length is limited by the inverter’s maximum input voltage.
Array
Multiple strings wired in parallel form the complete array. Parallel wiring adds currents together while maintaining the same voltage. The array connects to the inverter(s) for DC-to-AC conversion.
Array Power (kW) = Number of Panels × Panel Wattage (W) / 1,000Types of Solar Arrays
Solar arrays are categorized by their mounting location and structure. Each type has distinct design considerations.
Rooftop Array
Panels mounted on residential or commercial roofs using flush-mount or tilt racking. Constrained by roof area, orientation, pitch, and structural capacity. Accounts for over 80% of residential installations.
Ground-Mount Array
Panels installed on ground-mounted racking systems. Offers flexibility in tilt, azimuth, and row spacing. Common for utility-scale projects and large commercial installations where roof space is insufficient.
Carport Array
Panels integrated into overhead parking structures. Provides dual-use value — electricity generation plus vehicle shade. Higher structural costs but no land consumption. See solar carport for details.
Tracking Array
Ground-mount panels on single-axis or dual-axis trackers that follow the sun’s path. Increases energy production by 15–25% over fixed-tilt arrays, but adds mechanical complexity and maintenance costs.
When using solar design software to lay out an array, always verify that string lengths fall within the inverter’s MPPT voltage window across all temperature extremes. Cold temperatures increase voltage — a string that’s safe at 25°C may exceed the inverter’s maximum input voltage at -10°C.
Key Metrics & Calculations
Understanding array performance requires familiarity with these core metrics:
| Metric | Unit | What It Measures |
|---|---|---|
| Nameplate Capacity | kWp / kWdc | Total rated power of all panels under STC |
| Specific Yield | kWh/kWp | Annual energy production per kW of installed capacity |
| Performance Ratio | % | Actual output vs. theoretical maximum (typically 75–85%) |
| Capacity Factor | % | Actual output vs. output if running at full power 24/7 |
| DC/AC Ratio | ratio | Array DC capacity divided by inverter AC capacity (typically 1.1–1.3) |
| String Voltage | V | Sum of panel voltages in a series string |
Annual kWh = Array Capacity (kWp) × Peak Sun Hours (h/day) × 365 × Performance RatioPractical Guidance
Array design affects every downstream component — inverter selection, wiring, structural engineering, and financial projections. Here’s role-specific guidance:
- Optimize layout before sizing. Use solar design tools to test multiple array configurations. A smaller, well-placed array often outperforms a larger array with partial shading.
- Match panels within each string. Mixing panel wattages or orientations within a string forces all panels to operate at the lowest performer’s current, reducing output for the entire string.
- Account for all setback requirements. Fire codes (IFC), local building codes, and utility rules mandate setbacks from roof edges, ridges, and valleys. These reduce usable area significantly on smaller roofs.
- Design for the inverter’s MPPT range. Calculate string voltage at both minimum (hot summer) and maximum (cold winter) temperatures to ensure the array stays within the inverter’s operating window year-round.
- Verify structural capacity first. Before installing, confirm the roof can support the array’s dead load (typically 2.5–4 psf for flush-mount). Older roofs may need structural reinforcement.
- Maintain consistent row spacing. Follow the designer’s specified inter-row spacing to prevent self-shading. Even small deviations compound across large arrays.
- Label all strings clearly. Mark each string with its identifier at both the panel and inverter end. This simplifies future troubleshooting and maintenance.
- Test each string before commissioning. Measure open-circuit voltage and short-circuit current for every string. Compare against design values to catch wiring errors before energizing the system.
- Explain array size in context. Customers understand “covers 80% of your electricity” better than “8.4 kW array.” Translate technical specs into bill savings and energy independence percentages.
- Show the layout visually. Use solar design software to generate a visual array layout on the customer’s actual roof. Seeing their home with panels builds confidence and reduces objections.
- Address aesthetics proactively. All-black panels and flush-mount racking are popular for customers concerned about appearance. Offer these options before the customer raises the concern.
- Present expansion options. If the roof has additional space, mention future expansion potential. Design the initial inverter and electrical infrastructure to accommodate a larger array later.
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Real-World Examples
Residential: 8 kW Rooftop Array
A homeowner in Phoenix, Arizona, installs a 20-panel array (400W each) on a south-facing roof at 18° tilt. The array is configured as two strings of 10 panels, feeding a 7.6 kW string inverter. Annual production reaches 13,600 kWh with a specific yield of 1,700 kWh/kWp — enough to offset 95% of the household’s electricity consumption.
Commercial: 200 kW Flat-Roof Array
A distribution center in New Jersey installs 400 panels (500W each) on a flat TPO roof using ballasted tilt racking at 10°. The array is divided across four string inverters with optimizers for partial-shade management. East-west row spacing of 1.2 m keeps self-shading losses below 2%. The system produces 240,000 kWh/year, saving the business approximately $33,600 annually.
Utility-Scale: 5 MW Ground-Mount Array
A solar farm in North Carolina uses 9,500 bifacial 530W panels on single-axis trackers. The array is organized into 380 strings of 25 panels each, feeding 10 central inverters. Tracker-adjusted specific yield reaches 1,550 kWh/kWp. The bifacial gain adds 8–12% over monofacial panels due to ground-reflected light captured by the rear side.
Impact on System Design
Array configuration decisions cascade through the entire system design. Here’s how key array choices affect other components:
| Array Decision | Impact on System |
|---|---|
| Panel count and wattage | Determines inverter sizing, electrical panel capacity, and interconnection requirements |
| String configuration | Sets DC voltage and current, affecting wire gauge, conduit sizing, and inverter MPPT selection |
| Tilt and azimuth | Controls production profile, self-shading, and structural wind/snow loading |
| Row spacing | Balances energy density (kW/m²) against shading losses — tighter rows mean more capacity but more inter-row shading |
| Module-level electronics | Optimizers or microinverters add cost but mitigate partial-shade losses and enable panel-level monitoring |
A DC/AC ratio of 1.15–1.25 is the sweet spot for most residential and commercial arrays. This means the array’s DC capacity slightly exceeds the inverter’s AC rating, which maximizes inverter utilization during non-peak hours while accepting minor clipping losses during peak production.
Frequently Asked Questions
What is the difference between a solar panel and a solar array?
A solar panel (module) is a single unit containing 60–144 solar cells that generates 350–600W. A solar array is the complete collection of panels in a system, wired together in series and parallel strings. A typical residential array contains 15–30 panels, while commercial and utility-scale arrays can contain hundreds or thousands.
How many solar panels do I need for my home?
The number of panels depends on your annual electricity consumption, local solar irradiance, panel wattage, and roof conditions. As a rough guide: divide your annual kWh consumption by your area’s specific yield (kWh/kWp), then divide by the panel wattage. For example, a home using 10,000 kWh/year in a 1,500 kWh/kWp location needs about 6.7 kWp, or 17 panels at 400W each.
Can I mix different solar panels in one array?
Mixing different panels within the same string is not recommended, as the string’s current is limited by the weakest panel. However, you can use different panel types on separate strings connected to different MPPT inputs on the inverter. This approach is common when expanding an existing system or working with multiple roof faces that require different panel sizes.
What is the optimal tilt angle for a solar array?
For maximum annual energy production, the optimal tilt angle roughly equals the site’s latitude. However, practical factors like roof pitch, snow shedding, wind loading, and panel row spacing often take priority. A tilt within 10–15° of optimal typically loses less than 5% of annual production. Use solar design software to model the exact impact of tilt choices on your specific project.
About the Contributors
Content Head · SurgePV
Rainer Neumann is Content Head at SurgePV and a solar PV engineer with 10+ years of experience designing commercial and utility-scale systems across Europe and MENA. He has delivered 500+ installations, tested 15+ solar design software platforms firsthand, and specialises in shading analysis, string sizing, and international electrical code compliance.
CEO & Co-Founder · SurgePV
Keyur Rakholiya is CEO & Co-Founder of SurgePV and Founder of Heaven Green Energy Limited, where he has delivered over 1 GW of solar projects across commercial, utility, and rooftop sectors in India. With 10+ years in the solar industry, he has managed 800+ project deliveries, evaluated 20+ solar design platforms firsthand, and led engineering teams of 50+ people.