The denominator matters.
PV conversion compares electrical output with incident solar input. An inverter’s DC-to-AC efficiency uses another boundary. A charge/discharge energy ratio uses yet another. Similar percentage signs do not make these measurements interchangeable.
Sources: US Department of Energy: PV performance and efficiency · SAM help: PV inverter models · SAM help: battery results
Use a matched energy accounting window.
For a hypothetical AC round-trip test, 1,000 Wh measured entering and 800 Wh leaving would give 80% only when the accounting window, starting/ending storage state and included loads are defined consistently. Rated battery capacity divided by recharge input does not substitute for measured discharge output. The figure is invented arithmetic, not a measured product result.
Sources: SAM help: battery results
Peak, weighted and operating efficiency differ.
SAM supports part-load inverter curves and separately displays weighted efficiency. One quoted value does not describe every load point. For a buyer, ask for the load, voltage, temperature, boundaries and method. Keep standby energy visible and avoid applying a modeled conversion loss to an output that already includes it.
Sources: SAM help: PV inverter models
What this changes when you shop.
- Keep PV, inverter and round-trip boundaries separate.
- A nominal-capacity ratio is not measured round-trip efficiency.
- Use each loss once, at its documented boundary.
Sources, scope and corrections.
Conceptual buying guidance. Numerical examples are explicitly hypothetical; no exact product or installation is approved by this article.
Primary concept sources
- US Department of Energy: PV performance and efficiency
Conversion efficiency, temperature and reflection; not a forecast for a particular roof.
Reviewed 2026-11-07. Publication date not established; review date is not a publication or experiment date.
Source access and provenance
Direct source captured.
Captured 2026-11-08T01:51:11.720205+00:00 · SHA-256
89a3646b7e351a22092b9ecbbd24e681fa0d42481256254457ccbae6ea50688e - SAM help: PV inverter models
DC-to-AC conversion, part-load curves and weighted efficiency; no universal inverter efficiency is assumed.
Reviewed 2026-11-07. Publication date not established; review date is not a publication or experiment date.
Source access and provenance
Direct source captured.
Captured 2026-11-08T01:51:11.503925+00:00 · SHA-256
5951a1ca3156eb556662c336798386d7557884a26acb62c0a1c8ca12561bb19f - SAM help: battery results
Battery Storage Results: charge/discharge energy, temperature and separately modeled ancillary and converter losses.
Reviewed 2026-11-07. Publication date not established; review date is not a publication or experiment date.
Source access and provenance
Direct source captured.
Captured 2026-11-08T01:51:10.867215+00:00 · SHA-256
ef91e5d1d4d69173f3135b3767c78571fe44ebd43bd409dfbdfbe9bba39ff4cd
Illustration rights and meaning
Original site illustrations authorized for SolarCompare publication; no third-party artwork is reproduced. Source documents and publisher media retain their own rights. Conceptual diagrams and explicitly hypothetical arithmetic. No illustration is a measured curve or manufacturer drawing.
Article history
- · Initial publication. No subsequent correction is recorded in this revision.
New evidence is reviewed outside the build. A correction changes the article revision and records its date and reason; original source publication dates remain separate. Held observations stay held in the performance library until the source discrepancy is resolved.