National Home Inspector Exam Prep Podcast

12 - Alternative Energy and Generators: Solar PV, Wind Turbines, Generators

Season 1 - Electrical Systems ⚡ Season 1 Episode 12

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Alternative energy systems are increasingly common but typically out of scope for standard home inspections. This episode introduces these systems and helps inspectors recognize components and limitations.

Common Residential Systems:

  • Solar photovoltaic (PV)
  • Wind turbines
  • Solar water heating
  • Passive solar design
  • Ground-source heat pumps
  • Water-source heat pumps

Home Inspector Actions:

  • Report presence of system
  • Disclaim inspection
  • Recommend specialist evaluation for condition and function
  • Note permit requirements (few systems may be installed without permits)

Solar Photovoltaic (PV) Systems

Grid-Connected (Most Common):

  • Connected to utility grid
  • Provides some/all occupant electricity during daylight
  • Utility provides electricity when system insufficient
  • Excess electricity fed back to grid (net metering—utility may pay)
  • Most systems home inspectors see are grid-connected

Stand-Alone:

  • Not connected to utility grid
  • May serve one/few loads or entire house
  • Batteries/generators provide power at night
  • May include wind turbine supplement

System Components:

  1. Solar arrays (panels on roof/ground)
  2. DC disconnect switch (service/safety device)
  3. Inverter (converts DC to AC)
  4. AC disconnect switch (service/safety device)
  5. Backfed circuit breaker (connects to house panel—should be labeled and secured)
  6. Conduit/conductors (EMT, MC common)
  7. Mounting hardware
  8. Waterproofing (roof/wall penetrations)

Key Requirements:

  • PV conductors identified where accessible
  • PV conductors NOT in same conduit as other system conductors
  • Conduit/boxes labeled as containing PV conductors
  • Non-current-carrying metal parts grounded
  • Emergency access pathways on roof (new requirement—36" wide, separate planes)
  • Arrays set back from roof ridge 18-36" (new requirement)

Typical Defects (If Reported):

  • PV system disconnected/not functioning (check inverter display)
  • Backfed breaker not secured in panelboard
  • Components not labeled
  • Absent disconnect switches
  • Exposed conductors
  • Metal components not bonded
  • Panels cover vents/exhausts (okay if adequate spacing)
  • Damaged panels (scratched glass)
  • Significant shading of arrays

Wind Turbines

Key Components:

  • Rotor and generator module
  • Inverter, disconnects (similar to solar PV)
  • Tower (self-supporting or guy cables)
  • Surge protective device (lightning arrestor)
  • Grounding electrode connection

Generators

Transfer Switch (REQUIRED):

  • Disconnects house from grid while generator provides power
  • Prevents dangerous backfeeding into utility grid (fatal shock hazard to utility workers)
  • May be automatic or manual

Key Takeaways

  • Alternative energy systems typically out of scope
  • Report presence, disclaim, recommend specialist evaluation
  • Solar PV most common alternative energy system
  • Generators require transfer switches (prevent backfeeding)
  • Few systems may be installed without permits

IRC/NEC References

IRC 2018: R324, R327, Chapter 23 NEC 2017: Article 690 (PV), Article 694 (wind)

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