than typical home rooftops. Bifacial panels, which capture light from both the front and back of the panel, add measurable output in ground-mount or elevated installations with reflective surroundings, but the benefit is much smaller on a standard flush roof mount. Inverter types. An inverter converts the direct current (DC) electricity panels produce into the alternating current (AC) electricity a home actually uses, and the choice of inverter architecture is one of the bigger cost and performance decisions in a system design. A string inverter connects a series of panels to one central unit; it's the lowest-cost architecture, but one shaded or underperforming panel can drag down the output of the entire string, so it works best on simple, largely unshaded roofs. Microinverters place a small inverter at each individual panel, eliminating that shading penalty and providing panel-level production monitoring, at a higher upfront equipment cost; manufacturers typically back microinverters with the longest warranties in the industry, commonly around 25 years. Power optimizers pair a DC optimizer at each panel with a single central inverter, conditioning each panel's output individually before it reaches the shared inverter — a middle-ground architecture that solves the worst of string inverters' shading problem without the full cost of microinverters at every panel. Hybrid inverters combine a solar inverter and a battery inverter in a single unit, managing solar production, battery storage, and grid interaction together, and are the typical choice for homeowners who want to keep a future battery addition simple even if they aren't installing one immediately. Battery chemistry. Nearly all residential battery storage sold today is lithium-ion, and within that category the market has shifted decisively toward one chemistry. Per BloombergNEF's global energy storage market tracking, LFP (lithium iron phosphate) batteries account for roughly 90% of new annual lithium-ion storage capacity additions, driven by superior thermal stability, a longer cycle life, and a cost advantage over the alternative. NMC (nickel manganese cobalt) batteries, the older residential storage chemistry, are being phased out of home energy storage in favor of LFP, though NMC remains more common in electric vehicles where its higher energy density per unit of weight matters more than it does for a battery sitting in a garage or utility closet. Lead-acid batteries are a legacy technology found mostly in older off-grid systems, with a much shorter usable life than either lithium chemistry. Typical installed cost for solar panels. Two respected

SOURCE: Chief Appraiser Knowledge Base — Solar PV System Components and Typical Installed Costs Compiled from: National Renewable Energy Laboratory (NREL) Best Research- Cell Efficiency Chart; Lawrence Berkeley National Laboratory, "Tracking the Sun" (installed residential PV pricing); EnergySage 2026 Marketplace Intelligence Report (residential solar and battery pricing); BloombergNEF, global energy storage market reporting (battery chemistry); SEIA / Wood Mackenzie U.S. Solar Market Insight (industry structure); 26 U.S.C. § 25D, Residential Clean Energy Credit (expiration) Last reviewed: August 2026 ===================================================================== Solar PV System Components and Typical Installed Costs This file answers a different question than the rest of the Solar PV section of this library. It doesn't address what a solar system adds to a home's appraised value — that depends on ownership status and local market evidence, and is covered in Solar PV: Real vs. Personal Property & Valuation. This file answers a more basic question a seller, buyer, or agent often asks first: what is this system actually made of, and what does something like it typically cost to install. Cost data here comes from national marketplace and government sources, updated annually — it describes national trends, not a quote for any specific house. Panel types and efficiency. The large majority of residential panels sold today are monocrystalline silicon, cut from a single silicon crystal, distinguished mainly by cell architecture. According to NREL's Best Research-Cell Efficiency Chart, which tracks laboratory and commercial efficiency records across technologies, TOPCon (tunnel oxide passivated contact) cells have become the current mainstream commercial standard, with typical commercial module efficiency in the roughly 21.5%-24.5% range, and have largely displaced the older PERC cell architecture that dominated the previous generation of panels. HJT (heterojunction) cells sit a tier above TOPCon, at roughly 24%-25.5% commercial module efficiency, with better performance in high- temperature conditions, typically at a price premium. Polycrystalline panels, cut from multiple silicon fragments rather than a single crystal, run meaningfully lower in efficiency and have largely been discontinued for new residential rooftop installations. Thin-film panels are lightweight and lower-efficiency, used mainly in niche applications like recreational vehicles or some commercial and building-integrated products rather than typical home rooftops. Bifacial panels, which capture light from both the front and back of the panel, add measurable output in ground-mount or elevated installations with reflective surroundings, but the benefit is much smaller on a standard flush roof mount. Inverter types. An inverter converts the direct current (DC)

THIRD EDITION Solar Panels — Devices containing solar cells that are used to absorb the sun’s rays and convert them into electricity or heat. Sole Proprietorship — A business enterprise net worth that belongs entirely to one individual. Sonar — An apparatus that detects the presence of, or determines the distance or direction of, an object underwater by receiving and interpreting sound from the object. Span of Control — The number of employees supervised by each manager. Spatial — The location of, proximity to, or orientation of objects with respect to one another in N-dimensional space. Generally, refers to phenomena that can be mapped in two or three dimen- sions on or near the earth’s surface. Spatial Data Analysis — The study of the relationship between location-related data and property data, including property characteristics, market data, estimated values, and sales ratios. Spatial Resolution — 1) The ability of an entire remote sensor system, including lens, antennas, display, exposure, processing, and other factors, to render a sharply defined image; and 2) A measure of the smallest angular or linear separation between two objects that can be resolved by the sensor. Spearman Rank Test — Tests the association between two ranked variables. Specifically, as the value of one variable increases, does the other variable tend to increase or decrease? This is a standard nonparametric test useful in examining assessment bias. Special Assessment Area — A geographic area where additional funds are collected to provide services in a municipality. Also known as Special Rate Area. Special Property Tax — A tax that applies to a single class of property (for example, oil and gas properties, motor vehicles) and differs substantially in one or more respects from the general property tax. Note: Such difference may be in the base of the tax (for example, it may consist of gross earnings instead of property values), in the rate, or in important administrative aspects. Compare General Property Tax. Special Tax — 1) In general, an unusual, extraordinary, or unique tax; and 2) Specifically, as applied to property taxes, a) a property tax that is levied in addition to the levying of the regular annual property tax; and b) a property tax levied for a single purpose rather than for the general purposes of government. Special-Use Properties — Properties that have a very specific use and might be appropriate for only one or a very limited number