- AC (alternating current)
- The kind of electricity your home outlets supply. Inverters convert the DC power panels make into AC.
- Anti-islanding
- A safety feature that shuts off a grid-tied inverter during a power outage so it can't send power into lines that utility crews are repairing.
- Azimuth
- The compass direction your panels face. In the Northern Hemisphere, 180° (due south) produces the most energy.
- Backfeed
- Power flowing from your solar system into your home's wiring or the grid. Plug-in kits backfeed through an outlet.
- Balcony solar
- A small plug-in solar kit, usually 300 to 1,200 W, mounted on a balcony railing, wall or yard and plugged into an outlet. Also called plug-in solar.
- Battery (home)
- A rechargeable unit, typically 10 to 15 kWh, that stores solar energy for evening use or outage backup.
- Bifacial panel
- A panel that collects light on both sides, gaining extra output from light reflected off the ground or roof.
- Community solar
- A shared solar farm that you subscribe to for bill credits, with no equipment at your home.
- Critical loads panel
- A sub-panel holding the circuits a battery keeps powered in an outage, such as the fridge, lights and Wi-Fi.
- DC (direct current)
- The kind of electricity solar panels and batteries produce and store.
- Dealer fee
- A hidden charge built into many low-APR solar loans, often 15 to 30% of the loan, that raises the system price.
- Degradation
- The slow loss of panel output over time, typically 0.25 to 0.5% a year.
- Depth of discharge (DoD)
- How much of a battery's capacity you can use. Lithium iron phosphate batteries typically allow 90 to 100%.
- Derate factor
- A combined allowance for real-world losses from heat, wiring, dirt and inverters. 0.75 to 0.85 is typical.
- Escalator
- A yearly price increase written into a solar lease or PPA, commonly 0 to 3.9% a year.
- Grid-tied system
- A solar system connected to the utility grid, with no battery required. It shuts off in outages.
- Hybrid inverter
- An inverter that manages both solar panels and a battery.
- Interconnection
- Your utility's approval process to connect a solar system to the grid.
- Inverter
- The device that converts DC power from panels into AC power for your home.
- Islanding
- Running your home on solar and battery while disconnected from the grid during an outage. Requires special equipment.
- Kilowatt (kW)
- A measure of power, the rate of energy flow. System sizes are given in kW.
- Kilowatt-hour (kWh)
- A measure of energy, what your utility bills you for. One kW running for one hour equals one kWh.
- Lease
- An arrangement where a company owns the panels on your roof and you pay a fixed monthly fee to use them.
- LFP (lithium iron phosphate)
- A battery chemistry known for long life and safety, used in most home batteries and power stations.
- Microinverter
- A small inverter attached to each panel, so shade on one panel doesn't drag down the others.
- Monocrystalline
- Panels made from single-crystal silicon. The most common and efficient residential type today.
- MPPT charge controller
- A device that gets the most power out of panels when charging a battery. Standard in RV and off-grid systems.
- NABCEP
- The North American Board of Certified Energy Practitioners, the leading solar installer certification.
- Net billing
- A program that credits exported solar power at less than the retail price, as in California's NEM 3.0.
- Net metering
- A program that credits solar power you export to the grid, often at the full retail price, against power you buy later.
- Off-grid
- A system with no utility connection, relying on panels, batteries and often a generator.
- Payback period
- How many years it takes for savings to equal what you paid for the system.
- Peak sun hours
- The number of hours per day of full-strength sunlight (1,000 W per square meter). Most US locations get 4 to 6.5.
- Permission to operate (PTO)
- Your utility's final sign-off allowing you to switch on a grid-tied system.
- Plug-in solar
- See balcony solar. Ten US states had plug-in solar laws as of October 2026.
- Portable power station
- A box combining a battery, inverter and outlets that you can carry and recharge with folding solar panels.
- Power optimizer
- A panel-level device that boosts output under shade while using a single central inverter.
- PPA (power purchase agreement)
- An arrangement where a company owns your system and you buy the power it makes at a set price per kWh.
- Price per watt
- System cost divided by its size in watts. The best way to compare quotes. Around $2.60 to $3.40 in the US in 2026.
- Production guarantee
- A promise that a system will make a minimum amount of energy, with payment if it falls short.
- Rapid shutdown
- An electrical code requirement that de-energizes rooftop wiring quickly for firefighter safety.
- Round-trip efficiency
- The share of energy you get back from a battery after storing it, usually 85 to 95%.
- Self-consumption
- Using your solar power at home as it's made, rather than exporting it.
- Smart Export Guarantee (SEG)
- The UK scheme that requires certain suppliers to pay for exported solar power.
- Soft costs
- Non-hardware costs such as sales, permits, labor and overhead. Often half or more of a US solar quote.
- Solar Renewable Energy Certificate (SREC)
- A tradable certificate earned for each 1,000 kWh of solar power in some US states.
- STC (small-scale technology certificate)
- An Australian certificate that discounts the upfront cost of solar panels and batteries.
- String inverter
- A single central inverter connected to a string of panels. Usually the lowest-cost option.
- Surge watts
- The short burst of extra power a motor needs to start, often 2 to 3 times its running watts.
- System size
- The total rated power of your panels in kW. US homes typically install 6 to 12 kW.
- Tilt
- The angle of panels from horizontal. An angle near your latitude maximizes yearly output.
- Time-of-use (TOU) rates
- Electricity prices that change by time of day. Batteries can save money by shifting solar power to expensive evening hours.
- True-up
- The yearly settlement under net metering, when your credits and charges are reconciled.
- Watt (W)
- A unit of power. 1,000 watts equal 1 kilowatt.
- Watt-hour (Wh)
- A unit of energy, used for portable power stations. 1,000 Wh equal 1 kWh.
- 25D credit
- The US Residential Clean Energy Credit, a 30% tax credit for homeowner solar. It ended for systems installed after December 31, 2025.
- 48E credit
- A US business tax credit for clean electricity that companies that lease solar to homeowners can still claim under 2026 rules.
Missing a term? Suggest one.