Solar decisions get unnecessarily confusing when power, energy, pricing, contract assumptions and utility terminology are mixed together. This glossary keeps the definitions short and connects important terms directly to the calculator or review tool that checks them.
AC (alternating current)
The form of electricity used by normal household circuits and the utility grid. Solar panels produce DC electricity, which an inverter converts to AC for most home uses.
Azimuth
The compass direction a solar array faces. In PVWatts-style modeling, 180° represents south, 90° east and 270° west.
Battery capacity (kWh)
The amount of electrical energy a battery can store. Capacity is different from power: a 13.5 kWh battery does not necessarily deliver 13.5 kW of power.
Check this term →Battery charge power (kW)
The rate at which a battery or storage system can accept electrical power while charging. During an outage, this limit can cap how quickly surplus solar restores storage even when the array could provide more power.
Check this term →Battery continuous discharge power (kW)
The sustained power a battery system can deliver to household loads within its operating limits. It is separate from stored energy in kWh and from short-duration surge capability.
Check this term →Battery power (kW)
A general battery power term that can refer to charging or discharging, so the direction and duration should be stated. For backup planning, distinguish continuous discharge, short surge and continuous charging power instead of treating one kW rating as interchangeable with the others.
Check this term →Battery surge / peak power (kW)
A short-duration power capability used for brief high-demand events such as some motor starts. A surge rating should always be read together with its allowed duration or manufacturer test condition and should not be treated as continuous output.
Check this term →Clipping
Energy that could have been produced by the solar array but is limited because inverter AC output has reached its maximum. A DC/AC ratio alone does not tell you annual clipping kWh or clipping-loss percentage.
Check this term →Cost per watt ($/W)
Solar-only installed price divided by the system's DC watts. It is one of the cleanest ways to compare differently sized cash-price proposals when batteries and unrelated upgrades are separated.
Check this term →DC (direct current)
The form of electricity produced by photovoltaic modules and stored internally by many battery systems before conversion to household AC electricity.
DC/AC ratio
Solar-array DC nameplate divided by combined inverter continuous AC capacity. The ratio is a nameplate-sizing check, not an automatic verdict on design quality or a direct estimate of annual clipping loss.
Check this term →DC system size
The nameplate capacity of all solar modules added together, normally expressed in kilowatts DC. For mixed-module arrays, calculate each module group separately and add their DC watts.
Check this term →Degradation
The gradual reduction in solar-panel output over time. Performance warranties normally define minimum retained output or a maximum annual degradation schedule; that schedule is not the same as a weather or production forecast.
Check this term →Export limit
A utility or interconnection constraint on how much AC power a solar system may send to the grid at one time. It is different from inverter AC capacity, export compensation and net-metering credit rules.
Check this term →Export rate
The value a utility assigns to electricity a home sends to the grid. The export rate can equal the retail rate under some programs or be materially lower under net-billing structures.
Check this term →Inverter
Equipment that converts DC solar electricity into grid-compatible AC electricity. Residential systems can use a central/string inverter, microinverters or other architectures.
Check this term →kW (kilowatt)
A unit of power. Solar-array size and instantaneous battery output are commonly described in kW. It describes a rate of energy production or use, not an amount accumulated over time.
kWh (kilowatt-hour)
A unit of energy. Utility bills, annual home consumption, solar production and battery storage capacity are commonly expressed in kWh.
Net billing
A distributed-generation structure in which exported solar electricity is credited at a defined export value that can differ from the retail price paid for imported electricity.
Check this term →Net metering
A billing structure that credits customer-generated electricity exported to the grid according to program rules. Exact credit values, rollover rules and eligibility vary by utility and jurisdiction.
Check this term →PPA escalator
The annual percentage increase written into some solar power-purchase agreements. It compounds the contractual PPA rate and is different from a utility-rate escalation assumption used in a savings projection.
Check this term →PVWatts
A photovoltaic production model from the National Laboratory of the Rockies used by Home Solar Atlas for ZIP-specific planning estimates when location data are available.
Check this term →Solar offset
The share of a home's annual electricity consumption that a solar system is expected to produce over a year. A 100% annual offset does not mean the home is disconnected from the grid or that the utility bill will be zero.
Check this term →Solar yield (kWh/kW/year)
Annual solar production divided by installed DC system size. It normalizes a production forecast so two different system sizes can be compared on a common kWh-per-kW basis.
Check this term →TOU (time-of-use) rate
An electricity tariff where the price of grid electricity changes by time of day or day type. TOU pricing can materially change the value of daytime solar and evening battery discharge.
Check this term →Usable roof area
The portion of a roof that can realistically host solar modules after orientation, shade, obstructions, access paths, setbacks and other design constraints are considered.
Check this term →Utility-rate escalation
An assumed annual percentage change in future utility electricity rates. In a proposal it can materially affect long-term savings projections, so it should be separated from a lease/PPA contract escalator and treated as a scenario rather than a guaranteed forecast.
Check this term →Use the terms in a real proposal review
Start with the Solar Quote Review Tools when an installer proposal arrives, use the System Size Claim Checker for module-nameplate arithmetic, the Production Claim Checker for first-year kWh assumptions, the DC/AC Ratio Checker for inverter sizing and the Solar Financing Hub for loan, lease and PPA terms.