Residential & Commercial Solar Panels Installation Conditions Evaluation Guidelines

I. Site Condition Evaluation: The Foundation for Determining “Installability”

1. Rooftop Installation Scenario (Most Mainstream, for Residences and Factories)

2. Ground Installation Scenario (for Rural Areas, Factory Vacant Lands, and PV Power Stations)

• Space Scale: Each 1kW of modules requires 10-12㎡ of space (including access paths). For example, a 10kW system needs 100-120㎡ of unobstructed open space.
• Land Type: The land must be confirmed as “non-basic farmland and non-ecological protection red-line area”. Industrial land, idle homesteads, and barren slopes are preferred options.
• Terrain Conditions: Gentle terrain (with a slope ＜10°) is ideal; steep slopes (prone to landslides) and depressions (prone to waterlogging) should be avoided.
• Drainage Capacity: The site must have natural or artificial drainage capabilities (no water accumulation after heavy rains to prevent bracket corrosion).
• Grid Access Convenience: The site should be close to grid connection points (e.g., distribution boxes, transformers) to reduce cable losses (the cable length is recommended to be ＜50 meters).

3. Wall-Mounted Installation Scenario (Niche, for Building Facade Renovation)

• Wall Orientation: Same as rooftops, with priority given to due south.
• Wall Load-Bearing: Concrete walls should support ≥150kg/㎡, and brick walls ≥100kg/㎡ (avoid hollow bricks and lightweight partition walls).
• Installation Height: The bottom of modules should be ≥1.2 meters above the ground (to prevent pedestrian collisions), and the top should be ≤0.5 meters below the rooftop (for easy maintenance).
• Ventilation Conditions: A 10-15cm gap must be reserved between modules and the wall (for heat dissipation, to avoid efficiency reduction caused by high temperatures).

II. Solar Resource Evaluation: The Key to Determining “Power Generation Output”

1. Core Evaluation Indicators

2. Methods for Querying Solar Resources

• Authoritative Data Platforms:
  • China Solar Energy Resource Distribution Map (issued by the National Energy Administration, classifying regions into “abundant areas, relatively abundant areas, general areas, and poor areas”);
  • Public Meteorological Service Center of the China Meteorological Administration (provides access to local sunshine data from the past 10 years);
• Tool-Based Calculation:
  • Online Tools: PVsyst (a professional PV system simulation software that calculates H values when latitude and longitude are input), SolarGIS (a global solar resource map);
  • On-Site Measurement: Use a sunshine recorder to continuously collect data for 7-15 days (preferably on sunny days) and extrapolate annual data.

3. Correction for the Impact of Obstructions

• If shading causes shadow coverage of more than 5% on modules, power generation efficiency will decrease by over 20% (PV modules operate as “series circuits,” so local shading reduces overall power output);
• Solutions: Remove small obstructions (e.g., trees); if removal is not feasible, adjust the module installation position or use “shading-resistant modules” (e.g., polycrystalline half-cut modules, heterojunction modules).

III. Technical Parameter Evaluation: The Key to Ensuring “Proper Installation”

1. Module Selection Evaluation

2. Inverter Selection Evaluation

• Power Matching: The rated inverter power should be 0.8-1.2 times the total module power (e.g., an 8-12kW inverter is suitable for a 10kW module system);
• Type Selection:
  • Small Residential Systems (≤10kW): Choose “string inverters” (low cost, easy to install);
  • Large Industrial/Commercial Systems (＞30kW): Choose “central inverters” (high efficiency, easy to operate and maintain);
• Functional Requirements: Must include “anti-islanding protection, overload protection, and low-temperature startup” functions (to adapt to extreme weather); prioritize models with “WiFi/4G remote monitoring” (for easy access to power generation data).

3. Bracket and Foundation Evaluation

• Material Selection:
  • Rooftops/Walls: Choose “aluminum alloy brackets” (lightweight, corrosion-resistant, suitable for scenarios with limited load-bearing capacity);
  • Ground: Choose “hot-dip galvanized steel brackets” (high strength, wind-resistant, suitable for complex outdoor environments);
• Wind Resistance Rating: Must meet local maximum wind speed requirements (e.g., 12-level wind resistance for coastal areas, 10-level wind resistance for inland areas);
• Foundation Type:
  • Rooftops: Use “concrete weight foundations” for flat rooftops (no drilling required, to avoid damaging rooftop waterproofing); use “hook-type foundations” for sloped rooftops (fixed to rooftop purlins);
  • Ground: Use “concrete cast-in-place pile foundations” (depth ≥0.8 meters to prevent landslides).

IV. Policy and Compliance Evaluation: Avoiding the Risk of “Unusable Installations”

1. Grid Connection Policy Evaluation

• Grid Connection Application Process: Submit an application to the local power grid company (e.g., State Grid Corporation of China, China Southern Power Grid), providing an ID card/business license, property ownership certificate/land use certificate, and system design plan;
• Grid Connection Access Requirements: The power grid company will conduct on-site verification of the access point capacity (e.g., the remaining capacity of the transformer must be ≥ the system power). If the capacity is insufficient, an application for capacity expansion is required;
• Metering and Subsidies:
  • Full Feed-in: All generated power is sold to the grid, with electricity prices based on the local “PV benchmark electricity price” (national subsidies have been canceled in most regions since 2024, and prices follow local desulfurized coal electricity prices);
  • Self-Consumption with Surplus Feed-in: Priority is given to self-consumption, and surplus power is sold to the grid. The electricity price = residential/industrial-commercial electricity price (for self-consumed power) + local desulfurized coal electricity price (for surplus power sold to the grid).

2. Building Compliance Evaluation

• Rooftop Installation Approval:
  • Residences: For commercial housing, written consent from the property management company is required (to avoid affecting the building’s appearance or neighboring residents); for self-built houses, confirm that rooftop modifications comply with local building codes;
  • Industrial/Commercial Factories: A factory property ownership certificate must be provided to ensure that installation does not alter the building’s main structure;
• Fire Safety Requirements: A ≥1-meter fire-fighting access must be reserved between modules and rooftop edges, chimneys, or other facilities; inverters must be installed in well-ventilated, dry locations away from fire sources (with a maximum temperature of ≤40℃).

3. Environmental and Land Compliance

• Ground Installation: Confirm that the land does not fall within “ecological protection red lines, permanent basic farmland, or nature reserves”. A Construction Land Planning Permit is required if the land is classified as construction land;
• Module Recycling: Choose manufacturers with “module recycling qualifications” (since 2024, China has required PV module manufacturers to take responsibility for recycling to avoid potential environmental risks in the later stages).

V. Cost-Benefit Evaluation: The Core of Determining “Cost-Effectiveness”

1. Initial Investment Calculation (2024 Market Prices)

2. Operation and Maintenance (O&M) Cost Calculation

• Annual O&M Cost: Approximately 1%-2% of the initial investment (e.g., the annual O&M cost for a 10kW system is 300-920 RMB);
• Main Expenses:
  • Cleaning: Once per quarter (manual cleaning, costing 50-100 RMB per session);
  • Inspection: Once per year (checking brackets, inverters, and cables, costing 200-500 RMB);
  • Accessory Replacement: Inverters have a service life of approximately 10-15 years (the replacement cost is about 0.5 RMB/W); modules have a service life of 25 years and do not need replacement during this period.

3. Benefit Calculation and Payback Period

• Annual Power Generation: 10kW × 1200 hours = 12,000 kWh;
• Annual Benefits:
  • Self-Consumption Benefit: 12,000 kWh × 80% × 0.56 RMB/kWh = 5,376 RMB (savings on electricity bills);
  • Feed-in Benefit: 12,000 kWh × 20% × 0.38 RMB/kWh (desulfurized coal electricity price) = 912 RMB;
  • Total Annual Benefit = 5,376 + 912 = 6,288 RMB;
• Payback Period: Initial investment (35,000 RMB) ÷ Annual Benefit (6,288 RMB) ≈ 5.6 years (excluding subsidies; with local subsidies, the period can be shortened to less than 4 years).

VI. Summary of the Evaluation Process (Step-by-Step)

1. Preliminary Screening: Confirm the site type (rooftop/ground/wall-mounted) and exclude obviously unsuitable sites (e.g., insufficient load-bearing capacity, H＜800 hours);
2. Professional Testing: Hire PV service providers or construction institutions to test load-bearing capacity, solar resources, and grid access conditions;
3. Scheme Design: Determine module selection, installation angle, and grid connection mode based on test results;
4. Policy Confirmation: Consult the power grid company and housing construction department regarding grid connection and approval procedures;
5. Cost-Benefit Accounting: Calculate investment, O&M costs, and benefits based on the scheme to evaluate feasibility;
6. Contract Signing: Select qualified installers (must hold a General Contracting Qualification for Electric Power Engineering) and clarify warranty terms (25-year module warranty, 10-year inverter warranty).