Every term,
explained.

PVGIS is a scientific tool developed by the EU's Joint Research Centre that provides 25+ years of satellite-measured solar irradiance data for any location in Europe and beyond. VoltSun queries PVGIS for your exact GPS coordinates to calculate real solar potential — not regional averages.

A kilowatt-hour is the standard unit of electrical energy — the energy consumed by a 1,000-watt device running for one hour. In solar and EV contexts, kWh measures both what your panels generate and what your car needs, making it the core currency of every VoltSun calculation.

Kilowatt-peak is the standard measure of a solar system's maximum output under ideal lab conditions (1,000 W/m² irradiance, 25°C). A 6 kWp system of 400W panels contains 15 panels. Real-world output is typically 10–20% lower due to temperature, shading, and inverter losses.

Peak sun hours are the hours per day when solar irradiance equals 1,000 W/m² — the standard used to rate panels. A location with 4 peak sun hours receives the equivalent of 4 hours of full-intensity sunlight, even if the sun shines for longer. Portugal averages 5.2 peak sun hours; the UK averages 2.8.

Solar irradiance is the power of solar radiation reaching a surface, measured in watts per square metre (W/m²). It varies by location, season, time of day, and weather. PVGIS provides long-term irradiance averages for any GPS coordinate — the key input to VoltSun's yield calculations.

Monocrystalline solar panels are made from a single silicon crystal, giving them higher efficiency (20–23%) and better performance in low-light conditions compared to polycrystalline alternatives. Most modern residential installations use monocrystalline panels. VoltSun's calculations assume standard 400W monocrystalline panels.

A solar inverter converts the direct current (DC) produced by solar panels into alternating current (AC) used by home appliances and EV chargers. Without an inverter, solar power cannot flow into your home circuit. Most home solar systems include a string inverter or multiple microinverters, one per panel.

Self-consumption is the share of your solar output used directly on-site rather than exported to the grid. Higher self-consumption means greater bill savings, since you replace expensive grid electricity with free solar energy. EV owners who charge at home during daylight hours can achieve 70–90% self-consumption.

A home battery (such as a Tesla Powerwall or Huawei LUNA) stores surplus solar energy generated during the day for use at night or during peak-price periods. While not required to benefit from solar EV charging, a battery significantly increases self-consumption and can eliminate grid dependence for daily EV charging.

EV energy consumption, measured in kWh per 100 km, is the electric equivalent of fuel efficiency. A compact EV like the Fiat 500e uses ~14.5 kWh/100 km; a large SUV like the Rivian R1T uses ~27.9 kWh/100 km. VoltSun uses each model's official consumption figure to calculate the exact annual energy demand of your car.

AC (alternating current) charging is the standard method for home and workplace EV charging. Your car's onboard charger converts AC power to DC for the battery. Home chargers typically deliver 7 kW (single-phase) or 11–22 kW (three-phase). Solar panels produce DC, so AC charging passes through an inverter first — which most home solar systems already include.

The onboard charger (OBC) is the component inside your EV that converts AC electricity into DC for the battery. The OBC's maximum capacity limits AC charging speed — a 7.4 kW OBC cannot accept more than 7.4 kW, even from a 22 kW wallbox. DC fast chargers bypass the OBC entirely and charge the battery directly.

The payback period is the time it takes for a solar installation to recover its upfront cost through energy savings. For a typical European home with an EV, this is 7–12 years depending on electricity prices and local solar potential. After payback, the system generates free energy for its remaining 15–20 year lifespan, typically returning 2–3× the installation cost.

A feed-in tariff pays you a fixed rate for every unit of solar electricity you generate or export to the grid. The UK's FIT scheme closed to new applicants in 2019 and was replaced by the Smart Export Guarantee. Germany's Einspeisevergütung remains active. FIT rates vary by country, installation date, and system size.

The Smart Export Guarantee (SEG) is the UK government scheme that replaced the Feed-in Tariff. It requires licensed electricity suppliers to pay households for surplus solar energy exported to the grid. Unlike the FIT, SEG rates vary by supplier and tariff — ranging from 1p to over 15p per kWh. Only exported energy qualifies; self-consumed solar still saves you import cost separately.

Net metering is a billing arrangement where your meter tracks both electricity consumed from the grid and excess solar electricity exported to it. At billing time, you pay only for the net difference. Common in the US and parts of Europe (notably the Netherlands), net metering is one of the most straightforward ways to account for solar surplus across seasons.

A time-of-use (TOU) tariff charges different electricity rates depending on the time of day — higher during peak demand (typically evenings) and cheaper overnight. For EV owners with solar, TOU tariffs create a clear strategy: charge from cheap overnight grid electricity when solar is unavailable, and maximise solar self-consumption during daylight hours. Tariffs like Octopus Go and Octopus Agile are popular with UK EV drivers.

CO₂ intensity measures how much CO₂ is emitted per kWh of electricity generated on the national grid, in grams of CO₂ per kWh (gCO₂/kWh). It ranges from near-zero in Norway (~20 gCO₂/kWh from hydropower) to 400+ gCO₂/kWh in coal-heavy grids. VoltSun uses national CO₂ intensity data from the European Environment Agency to calculate how much carbon your solar panels prevent by displacing grid electricity.