understanding your solar system
Domestic solar jargon buster
Thinking about installing solar panels on your home? You’ll quickly discover that the solar industry comes with its own vocabulary, a collection of technical terms and abbreviations that might seem puzzling at first.
When you’re making decisions about a significant investment like solar panels, understanding the terminology will help you feel confident in your choices. Many of our customers tell us they initially felt overwhelmed by solar jargon during their research.
This guide explains the key terms you may encounter when exploring home solar systems. We’ve broken down the technical language into clear, straightforward explanations to help you navigate your solar journey with confidence. Knowing these terms will help you ask the right questions and understand the answers when speaking with installers and energy companies.
Solar panel technology terms
Photovoltaic (PV) panels are the most common type of solar panels for homes. These panels convert sunlight directly into electricity through the photovoltaic effect. When sunlight hits the silicon cells in the panel, it knocks electrons loose, creating an electric current. This direct current (DC) electricity then flows to an inverter, which converts it to alternating current (AC) for use in your home.
Monocrystalline panels are made from single-crystal silicon, giving them a uniform black appearance. They typically offer higher efficiency rates and take up less space, but cost more. Polycrystalline panels use multiple silicon crystals, giving them a blueish, speckled appearance. They’re generally less expensive but slightly less efficient, requiring more roof space to generate the same amount of electricity.
Kilowatt peak (kWp) measures the maximum power output a solar panel system can produce under ideal conditions. A typical UK home might have a 4kWp system, meaning it can generate up to four kilowatts of electricity at peak performance. Your system’s actual generation will vary throughout the day based on sunlight intensity and panel angle.
Solar cell efficiency describes how effectively a panel converts sunlight into electricity. Most residential panels operate at 15%-22% efficiency, with higher percentages indicating better performance. Higher efficiency panels cost more but generate more electricity in limited space, making them ideal for smaller roofs.
Degradation rate refers to how quickly solar panels lose efficiency over time. Quality panels typically degrade at about 0.5% per year, meaning they’ll still produce about 87.5% of their original output after 25 years. Manufacturers’ performance warranties usually guarantee at least 80% efficiency after 25 years.
Installation and system components
Inverters are essential components that convert the DC electricity generated by your solar panels into AC electricity used by household appliances. Without an inverter, your solar-generated electricity couldn’t power your home.
String inverters connect multiple panels in a series or “string.” They’re cost-effective but have a disadvantage. If one panel underperforms due to shade or dirt, it can reduce the output of the entire string. Microinverters address this. They attach to individual panels, converting DC to AC at each panel. They help improve performance when some panels are shaded, and make monitoring individual panel performance easier, though at a higher cost.
Mounting systems secure your solar panels to your roof. These include roof-mounted frames for pitched roofs, flat roof mounting systems that tilt panels at the optimal angle, and ground-mounting options for properties with suitable land. The mounting system must withstand decades of weather exposure while keeping panels at the ideal angle for maximum generation.
A generation meter measures all the electricity your solar panels produce, regardless of whether you use it in your home or export it to the grid. This differs from your standard electricity meter, which only measures power imported from or exported to the grid.
Your consumer unit (fuse board) connects your solar system to your home’s electrical wiring. It may need upgrading before solar installation to ensure it can safely handle the additional power source. Most systems require a dedicated solar circuit breaker within your consumer unit.
MCS certification (Microgeneration Certification Scheme) is a quality assurance certificate for renewable technology installations. Using an MCS-accredited installer like Electrical Innovations (Derby) Ltd ensures your system meets industry standards and qualifies for Government incentive schemes like the Smart Export Guarantee (see below).
Energy storage and management
Battery storage systems capture excess electricity generated during sunny periods for use when your panels aren’t producing enough power. Modern home batteries use lithium-ion technology similar to electric vehicle batteries. They typically store between 5-13.5 kilowatt-hours (kWh) of electricity, enough to power most homes through the evening and into the night.
Depth of discharge (DoD) refers to how much of a battery’s capacity can be used before recharging. A battery with 90% DoD means you can use 90% of its stored energy before needing to recharge it. Higher DoD percentages generally indicate more usable capacity, but very deep discharges can reduce battery lifespan.
Hybrid systems combine solar panels with other energy sources, such as wind turbines or backup generators. These systems provide more consistent power generation across different weather conditions and times of day. Many hybrid systems include battery storage to maximise the self-consumption of generated electricity.
The Smart Export Guarantee is a Government-backed scheme requiring large energy suppliers to pay small-scale generators for excess renewable electricity exported to the grid. It replaced the earlier Feed-in Tariff scheme. Under SEG, suppliers set their own rates, which vary between 15p-40p per kilowatt-hour exported.
An export tariff is the specific rate you’re paid for electricity you send to the grid. Different energy suppliers offer different rates, so shopping around can increase your returns. Some tariffs offer higher rates during peak demand periods, making a smart meter and battery storage even more valuable.
Performance and monitoring terms
Kilowatt-hour (kWh) is the standard unit for measuring electricity consumption and generation. One kWh equals 1,000 watts of power used for one hour. A typical UK household uses around 8-10 kWh of electricity daily. Your solar generation and export payments will be calculated in kWh.
Self-consumption refers to using the solar electricity you generate directly in your home rather than exporting it to the grid. Higher self-consumption rates typically mean better financial returns, as using your own solar power saves more than selling it through export tariffs.
Solar irradiance measures the power of sunlight hitting your panels, typically expressed in watts per square metre (W/m²). Higher irradiance levels produce more electricity. The UK receives average irradiance levels between 750-1,100 kWh/m² annually, with southern regions generally receiving more.
Performance ratio compares your system’s actual electricity output against its theoretical maximum. A high-performance ratio (typically 75%-85%) indicates an efficient operating system. Regular monitoring of this ratio helps identify potential issues before they significantly impact generation.
Monitoring systems track your solar generation, household consumption and grid imports/exports. Most modern systems include smartphone apps showing real-time and historical data. This information helps you optimise energy use patterns to increase self-consumption and reduce bills further.
Financial and regulatory terms
The payback period describes how long it takes for your solar system to save you enough money to cover its initial cost. Most UK installations reach this point within 7-10 years, leaving at least 15 years of effective ‘free’ electricity generation afterwards.
Return on investment (ROI) measures the financial benefits of your solar system over its lifetime compared to its initial cost. A typical UK domestic solar system might achieve 10%-15% ROI annually through bill savings and export payments, outperforming many traditional investments.
EPC rating (Energy Performance Certificate) grades your home’s energy efficiency from A (most efficient) to G (least efficient). Since 2012, properties have needed a minimum D rating to qualify for the best solar incentive rates. Improving your home’s energy efficiency before installing solar panels often increases your overall savings.
A DNO application (Distribution Network Operator) may be required before installing solar panels. The DNO manages your local electricity grid and needs to approve connections of generation systems over a certain size. Your installer typically handles this paperwork, but approval must be received before installation begins.
VAT rates on solar installations are currently 0% for most domestic installations, making solar more affordable. This reduced rate applies to both materials and installation labour costs for systems installed at residential properties. Commercial installations may be subject to standard VAT rates.
Understanding the solar landscape
These key terms should help you navigate conversations about home solar systems with greater confidence. The terminology might seem technical at first, but understanding these concepts will help you make informed decisions about your installation. When speaking with solar installers, don’t hesitate to ask for clarification if you encounter unfamiliar terms. Reputable companies will happily explain technical concepts in straightforward language.
At Electrical Innovations, we believe in making solar accessible through clear communication. Our team can guide you through the process, explaining each element of your system in plain English. Contact us today to discuss your solar options without the jargon. We’re here to answer your questions and help you understand exactly what you’re getting.
