Solar Energy Glossary
Essential terminology explained simply for balcony solar beginners.
Alternating Current (AC)
Electrical current that periodically reverses direction. This is the standard electricity supplied by UK power grids to homes, used for all household appliances. Your solar inverter converts DC power to AC.
Battery Storage
A rechargeable battery system that stores excess solar energy generated during the day for use in the evening or at night. Lithium batteries are most common, offering efficiency of 90-95% and lifespans of 10-15 years.
Building Regulations
UK government standards that define the minimum quality of buildings and installations. Most balcony solar systems under 4kW require no Building Regulations approval, but electrical sign-off is still necessary.
Direct Current (DC)
Electrical current that flows in one direction only. Solar panels generate DC electricity, which must be converted to AC (alternating current) by an inverter to power household appliances.
Distribution Network Operator (DNO)
The company that manages electricity distribution lines in your area. UK has 14 DNOs. You must notify your local DNO when installing solar systems, and they manage grid safety and export payments.
Feed-In Tariff (FIT)
A government payment scheme (now closed for new applications) that paid homeowners for electricity generated by solar systems. Replaced by the Smart Export Guarantee (SEG) in 2019.
Inverter
A device that converts DC electricity from solar panels into AC electricity for home use. Micro-inverters (for balcony systems) are attached to individual panels; string inverters serve multiple panels together.
Kilowatt (kW)
A unit of power equal to 1,000 watts. It measures the rate of energy flow. A balcony solar system is typically 0.3-0.8kW (300-800W).
Kilowatt-Hour (kWh)
A unit of energy equal to 1,000 watt-hours. This is what electricity bills measure: how much energy was consumed. A 400W solar system typically generates 450-550 kWh annually in southern UK.
Microgeneration Certification Scheme (MCS)
UK industry standard for certifying renewable energy installers. MCS-certified installers have been vetted for quality and competence. Certification is not mandatory for balcony solar but indicates professional standards.
Microinverter
A small inverter designed for single solar panels or small arrays. Ideal for balcony systems. Each panel has its own microinverter, optimizing performance if shading affects individual panels differently.
Ofgem
Office of Gas and Electricity Markets, the UK's independent energy regulator. Ofgem sets rules for renewable energy installations, grid connection, and export payments through the Smart Export Guarantee.
Payback Period
The time it takes for your system's energy savings to equal its initial installation cost. A £900 system with £100 annual savings has a 9-year payback period.
Photovoltaic (PV)
Technology that converts sunlight directly into electricity using silicon cells. All residential solar panels are photovoltaic panels, which is why they're often abbreviated as "PV panels."
Smart Export Guarantee (SEG)
UK government scheme allowing small-scale renewable energy generators to sell excess electricity back to the grid. Energy suppliers participating in SEG pay between 5-15p per kWh for exported power, depending on supplier.
Smart Meter
An intelligent electricity meter that records consumption in half-hourly intervals and transmits data to your supplier. Required to receive SEG payments for exported solar electricity. Installation is free for most UK households.
String Inverter
A single inverter that serves multiple solar panels connected in series (a "string"). Less common for balcony systems but used for larger installations. Typically more affordable than multiple microinverters.
Watt (W)
A unit of power measuring the rate of energy flow or consumption. A 400W solar panel produces 400 watts of power when receiving full sunlight. Light bulbs are also rated in watts.
Common Solar Terminology Combinations
400W System Generating 450 kWh Annually
A balcony solar panel rated at 400 watts will produce approximately 450-550 kilowatt-hours of energy each year (in southern UK). This is the total energy generated, measured in kWh, which is what your electricity bill measures.
Microinverter Efficiency of 95%
A microinverter that converts 95% of the DC power from your panels into usable AC power. The remaining 5% is lost as heat. Modern inverters typically achieve 94-97% efficiency.
Smart Meter Reading Shows 12 kWh Exported Today
Your smart meter recorded that 12 kilowatt-hours of electricity was sent back to the grid from your solar system. If your SEG supplier pays 12p per kWh, you'd receive £1.44 for that day's exports.
System Pays Back in 8 Years
Your £900 system generates £112.50 in savings annually (900 ÷ 8 = 112.50). After 8 years, cumulative savings equal your investment cost, and subsequent years are pure savings.