How long does a solar system last?Maintenance and lifespan.

A solar system usually runs for 25 to 30 years. In that time it needs little care. One part of the system has a shorter life, though: the inverter. This guide shows what to expect, so that your solar system delivers power over its whole life.

How long do modules and inverter last?

The modules have no moving parts. They age mainly through heat, light and weather, and their output falls slowly. Manufacturers state a product warranty and a performance warranty on their data sheets. The terms differ from one manufacturer to another and are given in the quote and the data sheet. With PV modules it is therefore worth looking closely at the warranty conditions.

The inverter works all the time. It converts the direct current from the modules into grid power and heats up as it does so. It usually lasts 12 to 15 years. Swissolar assumes that it has to be replaced once during the operating life of a system. Allow for this replacement when you work out the economics. The cost of the inverter and its installation depends on output and becomes concrete with a quote.

Reading the warranties properly

There are two warranties to tell apart. The product warranty covers defects in materials and workmanship. The performance warranty promises that after a certain time the modules still deliver a certain share of their rated output. The inverter has its own warranty. How long it lasts differs by manufacturer and device, and for some devices it can be extended. Ask for the terms in the quote and keep the documents safe. In a warranty case you need the invoice, serial numbers and data sheets.

When our own installers do the work, the system stays with one contact. That makes warranty cases easier, because nobody has to work out who built which part.

What does maintenance mean for a solar system?

Maintenance keeps the system in working and safe condition and slows wear. Solar systems are considered low-maintenance. There is no legal duty to maintain them. Even so, an inspection by specialists at longer intervals is worthwhile. We check:

• modules for cracks, discolouration and hot spots
• connectors and wiring
• fixings and mounting structure
• inverter and stored error messages
• yield figures compared with the forecast

An inspection makes most sense when someone is on the roof anyway, for example for cleaning or after a storm. It finds faults before they cost yield or become a safety risk. We also inspect systems that we did not build.

What is monitoring for?

Monitoring keeps watch over the yield of your system. Swissolar recommends it for all systems, because nobody looks at the inverter display every day for 20 to 25 years. Monitoring shows failures of the inverter or of a string and displays the yield by year, month and hour.

Most inverters today have remote monitoring built in that can be used at no extra cost. Alternatively an external data logger can monitor different inverters. If the yield falls compared with the previous year for no obvious reason, or the system reports a fault, a check is worthwhile. With us you receive an app after commissioning that shows yield and consumption.

How to spot a problem early

Most problems show up in the yield. These signs are a reason for a check:

• a yield clearly below the previous year
• error messages in the app or on the inverter
• one string that stands out from the others
• a module that looks discoloured, hot or damaged
• visible dirt, leaves or bird droppings on the modules

It is best to compare yield over a whole year, because weather and season vary a lot. If the comparison shows a gap you cannot explain, contact us. We look at the readings and on the roof to find the cause.

Do I have to clean the modules?

Usually not. On pitched roofs the rain washes the dust off. Cleaning is worthwhile with shallow modules, near farmland, trees or birds, and with a visible film of dirt. We check on site whether it pays off for your system, and tell you if it does not.

When cleaning is done, it uses demineralised water and a soft brush, with no chemicals and no pressure washer, and with fall protection. We advise against cleaning the modules yourself on the roof. You find the details on the page cleaning solar systems. It is best to combine cleaning with the inspection.

Is the system insured?

Who insures the system against damage depends on the canton. In most cantons a cantonal building insurer insures the buildings. Solar systems fixed to the building are generally covered there. The Lucerne building insurer, for example, covers fixed systems against fire and natural hazards, but not loss of yield. The GVZ (Zurich cantonal building insurance) counts solar energy systems among the installations insured with a building.

In cantons without a cantonal building insurer, the cover is set out in your policy with a private insurer. In German-speaking Switzerland this applies, for example, to Schwyz, Uri, Obwalden, Appenzell Innerrhoden and Upper Valais (Oberwallis). There, check whether natural hazards are included and whether the system is part of the sum insured.

Report a new system to your insurer after commissioning and compare the sum insured with the building costs. The same applies after an extension. What to do after a hailstorm is explained in the guide hail damage: what to do.

When is it worth looking at the whole system?

After ten to fifteen years, when the inverter is due, things in the house often change too. Perhaps you drive an electric car, have installed a heat pump or use more power during the day. A home battery as a retrofit may then make sense. If your roof still has room, the system can be extended. We discuss both at the inspection, with no obligation.

We calculate it for your system

Whether inspection, inverter, cleaning or extension, we look at your system on site. The site visit is free and without obligation. Within 72 hours afterwards you receive a binding quote for what your system really needs. If you are planning a new system, you find the costs under solar system cost and payback.