Plug-In Solar Glossary: 40 Terms Explained

Shopping for a balcony kit means wading through a lot of jargon. Here are the terms that matter, in alphabetical order.

A-D

• AC (alternating current): the electricity in your home’s outlets. The microinverter produces it.
• AC-coupled battery: a battery with its own inverter that plugs into an outlet and charges from surplus on the house circuit. Compared here.
• Anti-islanding: the safety function that shuts an inverter down within a fraction of a second when grid power disappears.
• Balkonkraftwerk: German for “balcony power plant”, the common name for plug-in solar there.
• Baseload: the power your home uses continuously (fridge, router, standby). The key number for sizing a kit.
• Bifacial panel: a panel that collects light from both sides. Worth it?
• BS 7671: the UK wiring regulations; Amendment 4 (2026) made room for plug-in solar.
• Clipping: when panels could produce more than the inverter’s maximum, the inverter caps output.
• DC (direct current): what solar panels produce.
• DC-coupled battery: a battery connected between panels and the inverter.
• Degradation: the slow loss of panel output over time, typically 0.3-0.5% a year.
• DNO: Distribution Network Operator, the company that runs local power lines in the UK.

E-L

• Export: power flowing from your home to the grid.
• G98: the UK engineering recommendation for connecting small generators, including notification rules.
• GFCI / RCD: ground-fault circuit interrupter (US) or residual current device (UK/EU). They cut power if current leaks to ground. Outdoor outlets should have one.
• Glass-free panel: a lightweight panel with a polymer front instead of glass, easier to mount on balconies.
• Interconnection agreement: the formal approval utilities normally require for any generator on the grid. Plug-in laws exempt small devices from it.
• Irradiance: the power of sunlight hitting a surface, in W/m².
• kWh (kilowatt-hour): the unit of energy on your bill. 1,000 W running for one hour.
• kWp (kilowatt-peak): panel capacity under standard test conditions.
• LFP / LiFePO4: lithium iron phosphate, a safe, long-lasting battery chemistry. Guide.

M-S

• MaStR: Germany’s Marktstammdatenregister, where balcony systems must be registered.
• Meter socket adapter (meter collar): a device installed at the meter to connect solar or batteries without panel rewiring. Not the same as plug-in solar.
• Microinverter: a small inverter for one to four panels.
• MPPT: maximum power point tracking, how an inverter or charger extracts the most power from a panel.
• Net metering: a billing scheme crediting exported power. Usually not available for plug-in kits.
• NRTL: Nationally Recognized Testing Laboratory (UL, Intertek, CSA and others).
• Offset-only: Utah’s term for systems that only reduce your own consumption, with no export credit.
• Payback period: how long it takes for savings to equal the kit’s price.
• Self-consumption: the share of solar output used in your home. Explained.
• Smart Export Guarantee (SEG): UK scheme that pays for exports, currently tied to MCS certification.
• Specific yield: kWh produced per kWp of panels per year, the best way to compare locations.

T-Z

• Tilt angle: the angle between the panel and the ground. Vertical is 90°.
• Time-of-use (TOU): tariffs where electricity costs more at certain hours. How it affects savings.
• UL 1741: US safety standard for grid-connected inverters.
• UL 3700: the US safety standard for plug-in solar systems. Explained.
• VDE-AR-N 4105: German grid connection rules for small generators.
• W (watt): a unit of power, the rate of energy flow at a moment.
• Wp (watt-peak): a panel’s rated output under standard test conditions.
• Zero export: a setup that prevents any power flowing to the grid. Details.

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