Solar energy audit: What’s included and when you need one

What a solar energy audit includes

A solar energy audit typically covers several diagnostic areas to determine whether your system is operating at full capacity. Auditors measure panel output, test the electrical system and review your monitoring history to find problems you can’t see from the ground. The scope depends on whether you’re dealing with a new system that never met expectations or an aging installation showing gradual decline.

Most professional audits include an infrared scan to find hot spots and failing cells, IV curve tests on sample panels or strings to measure electrical performance, and a safety check of breakers, disconnects and grounding. The auditor will also analyze your monitoring system data, comparing your actual production over the past 12-24 months to what the system should be generating based on your location, panel specifications, and local weather patterns.

If your system lacks monitoring or the data looks inconsistent, the auditor will conduct on-site performance testing using diagnostic equipment. They also look for dirt buildup, inspect wiring connections and confirm the panels are tilted as designed. Even small issues like shading from tree growth or a loose wire can significantly reduce output — and an audit is designed to catch those problems.

Performance monitoring and output analysis

Monitoring data is the starting point for diagnosing a system that isn’t performing, since most inverters and third-party monitors record production continuously. During an audit, the technician reviews your monitoring dashboard and historical data logs to spot trends that indicate trouble.

Historical data shows whether a dip is seasonal or a real fault. A slow, steady decline can point to aging panels or new shade from trees or buildings. The auditor compares your system’s output to expected performance benchmarks for your area and adjusts for weather variations. If your production consistently falls short despite good weather, that’s a red flag.

Many audits start with a remote review of your data and add an on-site visit if needed, then deliver a report on problems such as degraded panels or wiring faults so they can be fixed before they get expensive. You’ll receive a written report with performance charts showing exactly where your system is underperforming and by how much.

Electrical system and inverter diagnostics

The inverter turns your panels’ DC power into AC for your home, so the audit checks its output, temperature and efficiency. A failing inverter can cost you a large share of your production. The audit includes testing voltage and current across all components to verify proper operation.

Loose or corroded connections and damaged connectors can block current or cause voltage drop, and testing finds them so an electrician can fix them before they cause bigger problems. This is especially important for systems installed several years ago, as weathering and thermal cycling can degrade connections over time.

If your inverter has been displaying error codes, going offline frequently, or showing fluctuating output, these are symptoms the audit will investigate. The technician will test the inverter’s response to load changes and verify it’s communicating properly with your monitoring system. In some cases, inverter firmware updates or recalibration can restore lost performance without replacing hardware. For more on common inverter issues, see our guide on outdated solar technology.

Physical inspection of panels and mounting hardware

Auditors also check the roof’s condition, orientation and shading at different times of day, and whether the structure is sound. For existing systems, the auditor inspects the panels themselves for physical damage, soiling, micro-cracks, or discoloration that could indicate cell degradation.

The mounting hardware and racking system are checked for corrosion, loose bolts, or signs of water intrusion that could compromise both performance and safety. Even minor shifts in panel position due to loose mounts can alter the angle of incidence and reduce energy capture. The auditor will also look at the roof penetrations and flashing to ensure they’re still weathertight — a leaking roof is a problem that goes well beyond solar performance.

Specialized meters measure panel output, check for shading and evaluate how well the inverter is working. Thermal imaging cameras can reveal hot spots caused by failing bypass diodes or damaged cells that aren’t visible to the naked eye. If shading has become an issue due to new construction or tree growth, the auditor will document the impact and suggest remediation options.

When you should consider a solar energy audit

You don’t need an audit if your system is producing as expected and your monitoring shows consistent performance. But there are clear signals that an audit is worth the investment. Your monthly output has dropped 10 to 15% over the past year even though the weather was similar, or your inverter keeps showing errors or rebooting.

Other reasons to schedule an audit: your electric bills haven’t dropped as much as your installer projected, your monitoring system shows unexplained gaps or inconsistencies in data, or you’re planning to sell your home and want documentation of system performance for potential buyers. If you’re buying a home with an existing system, an audit before closing can reveal problems the seller may not have disclosed. For more on that process, see buying a home with solar.

A yearly check, plus one after any major storm, keeps small problems from growing. If your area experienced hail, high winds, or severe storms, even systems that appear undamaged can have micro-cracks or electrical issues that reduce output. An audit provides peace of mind and catches small problems before they become expensive failures.

Before you book an audit, run through the common causes in our underperformance guide.

What to expect from the audit report

The findings come together in a plain-language report that lists each problem, the recommended fix, and what it’s costing you in production and money. The report should include baseline data showing what your system was designed to produce, actual production figures over a defined period, and the performance gap expressed both in kilowatt-hours and dollar terms.

You’ll also receive prioritized recommendations: urgent repairs that affect safety or cause significant output loss, efficiency improvements that offer good return on investment, and optional upgrades that may enhance performance but aren’t strictly necessary. The report should include cost estimates for recommended work and projected savings or production increases from each action.

A good report includes recommendations, cost estimates and the expected payback for each fix. Use the report to hold your installer accountable if the system is under warranty, to plan maintenance and upgrades, or to negotiate with a service provider if you’re seeking competitive bids for repairs. Keep the report with your system documentation — it’s a valuable record if you sell the home or file an insurance claim after storm damage.

DIY monitoring vs. professional audit

If you have a monitoring system installed, you can track your solar production daily and compare it to expected output using online calculators or your installer’s projections. Many monitoring platforms flag anomalies and send alerts when production drops unexpectedly. This DIY monitoring is useful for spotting obvious problems like a complete inverter failure or a sudden drop in output.

Watching your own data catches big problems, but only a professional has the equipment for infrared scans and IV curve testing. You can’t see micro-cracks in solar cells, measure the IV curve of individual panels, or test for ground faults without the right equipment. Professional audits also include liability — if the auditor damages something or misses a safety issue, they’re accountable.

Start with your monitoring data and a visual inspection. If everything looks normal but production is still low, or if you see error codes you can’t interpret, that’s when to call in a professional. The cost of an audit — typically a few hundred dollars for a residential system — is a fraction of the revenue you’re losing from an underperforming array. To connect with qualified professionals in your area, visit Find a Solar Installer.