Residential Solar PV Installation SOP

Purpose

Standardize residential solar PV (photovoltaic) installation. Combines structural roofing, electrical, + integration work. Quality install determines 25-year performance + insurance/warranty integrity.

Scope

Grid-tied residential PV systems 4-15 kW. Excludes off-grid (different design), ground-mount (different mounting), commercial > 25 kW, + battery-only retrofits.

Prerequisites

• System design complete (panel layout, electrical schematic)
• Permit pulled
• HOA approval (if applicable)
• Equipment on-site: panels, racking, inverter, balance-of-system, conduit, wire
• Crew: 1 lead + 2-3 helpers; 1 must be licensed electrician
• 3-5 days typical for residential install
• Fall protection equipment (mandatory)
• Weather: dry days, low wind, mild temps

Procedure

Day 1 - Pre-install + setup

1. Review approved permit + design with crew
2. Verify all equipment matches design
3. Set up scaffolding or roof anchors
4. Brief safety + tasks

Day 1-2 - Roof penetrations + racking

1. Mark rafters below intended panel locations
2. Drill pilot holes through roof + into rafter (minimum 2.5" into rafter)
3. Install standoffs / mounts:

• Flashing kit around mount
• Sealant between flashing + roof
• Lag bolts torqued to spec (typically 8-12 ft-lb on 5/16" lag)

1. Inspect each penetration for proper sealing
2. Install rails on standoffs
3. Level + align rails per design

Day 2-3 - Panel installation

1. Carry panels carefully to roof (one at a time; no stacking on roof)
2. Set panel onto rails
3. Clamp panel: end clamps at ends, mid clamps between
4. Verify spacing per design
5. Verify panel grounded to racking (continuous bonding)
6. Continue across array

Day 3 - DC wiring + roof penetrations

1. Connect panel DC wiring (positive + negative)
2. Run DC strings to inverter location
3. Use UV-resistant wire (PV-rated)
4. Through-roof penetration to inverter location
5. Conduit + flashing at each through-penetration

Day 3-4 - Inverter + electrical

1. Install inverter (typically wall-mounted near service panel, OR on rail next to panel for microinverters)
2. Run DC from panels → DC disconnect → inverter
3. Run AC from inverter → AC disconnect → service panel
4. Install monitoring system

Day 4 - Service panel integration

1. Backfeed breaker installed in service panel:

• Sized per inverter output + 125% safety
• 120% rule: solar + main breaker ≤ 120% of panel bus rating

1. Wire from AC disconnect → service panel
2. AC disconnect labeled per code

Day 4 - Final wiring + commissioning

1. Verify all connections torqued
2. Test DC voltage at panel strings (multimeter)
3. Test AC at inverter output (multimeter)
4. Energize: turn on AC disconnect first, then DC disconnect
5. Inverter syncs to grid (5-10 minutes typical)
6. Monitor production beginning

Day 5 - Inspection + commissioning

1. AHJ (Authority Having Jurisdiction) electrical inspection
2. Utility interconnection inspection
3. Permission to Operate (PTO) issued by utility
4. System fully active

Acceptance criteria

• All penetrations sealed + leak-tested (water spray check)
• All panels secured + grounded
• All electrical connections per NEC + manufacturer spec
• DC + AC voltages within tolerance
• System producing per design estimate (sunny day baseline)
• Monitoring system online
• Customer sign-off + utility PTO

Common pitfalls

• Inadequate rafter penetration: lag bolts pull out under wind/snow
• No flashing at mounts: roof leak in 1-3 years
• Wrong wire size for run length: voltage drop reduces production
• Inverter undersized: doesn't capture full panel output
• Backfeed breaker not 120% rule compliant: panel overload
• Skipping ground continuity: NEC violation; safety hazard
• Permit not closed before customer occupancy: legal issues
• Wrong DC disconnect type: doesn't break under load

Mounting types

Flush-mount (most common):

• Panels parallel to roof slope
• 2-4" gap for airflow
• Simple, cost-effective
• Best for standard pitched roofs

Tilt-mount (less common):

• Panels angled different from roof
• Optimizes sun angle (especially low-pitch roofs)
• More expensive
• Best for flat or low-slope roofs

Ground-mount:

• Separate scope; ground-mounted racks
• For homes with significant land
• No roof penetrations

Inverter types

String inverter:

• Single inverter; all panels connect to it
• for typical residential
• DC disconnect at inverter

Microinverter (or DC optimizer):

• One inverter per panel (or per pair)
• Eliminates string loss; better in shading
• More monitoring points

Hybrid (battery-ready):

• Inverter integrates with battery storage Tesla Powerwall, Enphase IQ Battery, FranklinWH integrations are common.

Battery storage

Separate but related:

• Reduce grid dependence
• Backup during outages
• Time-of-use rate optimization

Costs: added for typical battery system; 1-3 day install separate or combined.

Permits + utility coordination

Permits:

• Electrical permit
• Sometimes building permit (for structural mounts)
• Utility interconnection application

Utility process:

• Submit interconnection application (10-30 day approval)
• Install system
• Utility inspection (sometimes; often via electrical inspector)
• Permission to Operate (PTO) issued
• Net metering credit begins

Don't activate system before PTO; results in back-charging + fines.

Customer education

After install:

• Walk through monitoring system + app
• Show how to read production data
• Explain seasonal variation (winter less than summer)
• Provide warranty info (panels 25 years, inverter 10-25 years)
• Set up annual visual inspection
• Discuss battery upgrade option if not included

Cleaning + maintenance

• Annual visual inspection:
• Cleaning: typically (residential)
• Self-cleaning in most regions (rain handles it)
• Some warranty work covered by manufacturer

Lifespan + degradation

• Panels: 25-year warranty; 80% production after 25 years
• Inverter: 10-25 year warranty (replace once during system life)
• Cables: 25+ years
• Mounting: 25+ years if properly installed

System designed for 25-30 year operation.

References

• NEC Article 690 (Solar PV)
• IRC R324 (PV systems in residential)
• Manufacturer installation manuals (binding for warranty)
• NABCEP installation certification