What an inverter actually does
Solar panels generate DC electricity — current that flows in one direction at a voltage that varies with light intensity. The appliances in your home (and the UK national grid) operate on AC electricity — current that alternates direction 50 times per second at 230V. An inverter bridges this gap, continuously converting the variable DC output from your panels into stable 230V 50Hz AC power.
Modern inverters do considerably more than this basic conversion. They perform maximum power point tracking (MPPT), which continuously adjusts the electrical load on the panels to extract the maximum available power from whatever light conditions exist. They also monitor and log the output of the system, detect faults, and in a grid-connected installation manage the safe export of surplus electricity to the grid.
When the grid goes down, UK inverters are legally required to shut off automatically — a safety requirement called anti-islanding, which prevents electricity from flowing out onto the grid while engineers are working on it. This is why a standard grid-tied solar installation does not provide backup power in a blackout.
Types of inverter used in UK homes
String inverters connect all the panels in series (or parallel strings) to a single central unit. They are the most common and cost-effective option for unshaded, uniform roof installations. The weakness of a string inverter is that if one panel in the string is shaded or underperforming, it drags down the output of the entire string. Common UK brands include Fronius, SMA, and Growatt.
Microinverters attach individually to each panel and convert DC to AC at panel level. Because each panel operates independently, partial shading on one panel does not affect the rest. They also allow panel-level monitoring — you can see exactly how much each panel is generating. The trade-off is higher upfront cost and more components on the roof. Enphase is the dominant UK microinverter brand.
DC optimisers sit between a string inverter and each panel, performing per-panel MPPT without the full cost of microinverters. SolarEdge is the leading UK system using optimisers. They offer most of the shading resilience and monitoring benefits of microinverters at a lower cost than a full microinverter system.
Hybrid inverters connect to both your solar array and a battery, managing the charging and discharging of the battery alongside grid interaction. If battery storage is planned now or in the future, a hybrid inverter avoids the need to retrofit a separate battery inverter later.
How long do inverters last?
Solar panels routinely last 25–30 years. Inverters last 10–15 years on average. The components inside an inverter — capacitors, fans, and power electronics — operate under thermal and electrical stress and degrade over time in a way that the passive glass-and-silicon structure of a panel does not.
Most inverter warranties are 5–10 years, often extendable to 12–15 years for a fee. When comparing solar quotes, check the inverter warranty period alongside the panel warranty. A quote that includes a 5-year inverter warranty and a 25-year panel warranty almost certainly means the inverter will need replacing at some point within the system's commercial life.
An inverter replacement typically costs £500–£1,500 including labour, depending on type and brand. Budgeting for this in your system lifetime cost calculation will give you a more accurate picture of the true return on investment.
Maintaining your inverter
String inverters and hybrid inverters are typically installed in a garage, loft, or utility room. Keep the area around the unit clear — inverters need airflow to cool themselves and will throttle output or shut down if they overheat. Do not store items directly against the unit or block the ventilation grilles.
Check the inverter's status display or app weekly during peak generation months. Most modern inverters connect to a monitoring app (Fronius Solar.web, SolarEdge monitoring portal, Enphase Enlighten) that shows daily and cumulative generation. A sudden drop in output that is not explained by weather is often the first sign of a developing inverter fault.
If your inverter is displaying an error code, consult the manufacturer's documentation before calling an electrician. Many fault codes are transient and clear themselves; others require a qualified solar technician to assess. Your installer should be the first point of contact for warranty-period faults.