30 terms you'll run into while planning solar or battery storage, explained without the jargon — each linked to the calculator or guide that uses it.
The type of electricity used in your home and the grid. Solar panels produce DC, so an inverter converts it to AC before it can power household appliances.
The process of paying off a loan through fixed payments over time. See the Solar Loan Calculator for the standard amortization formula used for solar financing.
The unit of electrical current. Cable size, charge controllers and inverters are all rated in amps — see the Solar Cable Size Calculator.
The compass direction a panel faces. South-facing (in the northern hemisphere) is typically optimal — often a bigger factor in production than tilt angle. See the Roof Angle & Tilt Calculator.
One or more batteries wired together to form a storage system. Size one with the Battery Size Calculator.
A small component inside a panel that routes current around a shaded or damaged cell so it doesn't drag down the whole panel's output.
Regulates the flow of power from panels to battery so the battery isn't overcharged. See the Charge Controller Sizing Calculator.
The type of electricity solar panels and batteries natively produce and store, before an inverter converts it to AC for household use.
How much a panel's output shrinks each year, typically around 0.5% — used in the Solar ROI Calculator's 25-year production model.
The share of a battery's rated capacity you can safely use. Lithium batteries typically allow 90-100% DoD; lead-acid is usually limited to 50%. Explained fully in our battery storage guide.
A conservative multiplier (commonly 0.8) applied to a panel's rated output to account for real-world losses — inverter conversion, wiring, heat, dust. Built into the Solar Panel Calculator.
A fixed rate paid per kWh of solar exported to the grid, common in the UK, Germany and Australia — distinct from net metering. See the Net Metering Calculator.
A solar system connected to the utility grid, able to draw power when production is low and (often) export excess. The opposite of off-grid.
The contract with your utility that governs how your solar system connects to the grid, including your net metering or net billing terms.
Converts DC power from panels/battery into AC power your home can use. Size one with the Inverter Size Calculator.
kW (kilowatt) measures instantaneous power — how fast energy flows. kWh (kilowatt-hour) measures total energy used or produced over time. A 6kW system running for 1 hour at full output produces 6 kWh.
The most common home battery chemistry today — high depth of discharge, long cycle life, and better thermal stability than older lithium chemistries. Compare cost with the Battery Storage Cost Calculator.
The technology most modern charge controllers and inverters use to continuously find the optimal voltage/current combination for maximum power output — more efficient than older PWM technology.
A billing arrangement where excess solar you export earns a credit, typically near the retail rate, offsetting what you import later. Full explanation in our net metering guide.
Similar to net metering, but exports are credited at a lower rate (often tied to wholesale prices) rather than the full retail rate — increasingly common as utilities phase out traditional net metering.
A solar system with no utility connection at all — every watt used has to come from panels or battery. See our off-grid solar guide and the Off-Grid System Calculator.
A panel's rated output under Standard Test Conditions (1,000 W/m² irradiance, 25°C cell temperature) — real-world output is usually somewhat lower, which is why calculators apply a derate factor.
How many years until cumulative savings equal what you paid for the system. Check yours with the Solar Payback Period Calculator.
The equivalent number of hours per day at 1,000 W/m² irradiance — not the same as daylight hours. Look yours up with the Solar Irradiance Calculator.
A contract where a third party owns the panels on your roof and sells you the power at a per-kWh rate, usually below utility price. Compare against ownership with the Lease vs. Buy vs. PPA Calculator.
An older, less efficient charge controller technology that requires panel voltage to closely match battery voltage — largely superseded by MPPT in modern systems.
The net financial return a system generates relative to what it cost. Model yours with the Solar ROI Calculator.
A tradable certificate representing 1 MWh of solar production, sellable for extra income in states with SREC markets (e.g. New Jersey, Pennsylvania, Illinois, Massachusetts, Maryland) — separate from net metering credits.
A string inverter converts DC to AC for a whole "string" of panels at once — cheaper, but one shaded panel can drag down the whole string. Microinverters work panel-by-panel, costing more but limiting shade losses to just the affected panel. See the Shading Loss Calculator.
The loss of voltage (and power) as current travels through a cable — the main reason cable size matters. Calculate the right size with the Solar Cable Size Calculator.
A panel's open-circuit voltage (Voc) and short-circuit current (Isc) — the maximum voltage and current it can produce, used when sizing charge controllers and wiring strings safely.