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Residential Solar System Warranties: What to look for, what to watch out for

by James Martin II on 9 May, 2011

in Installation advice,Inverters,Batteries & Energy Storage,Off-grid solar power, Stand-alone solar power, Remote solar power

When thinking about installing a residential solar power system, it is important to carefully consider the types and durations of the warranties offered by solar system installers. This article explains the differences between the types of warranties that may be available to you when shopping around for a solar photovoltaic system for your home.

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What types of warranties are usually available for solar power systems?

When deciding on a system and its warranty, it is important to know exactly what you are signing up for in order to avoid surprises long after you have installed your system. There are several different types of solar power system warranties, offering coverage of different parts of a system, that you may encounter when shopping around for the ideal system for your home energy consumption needs. These are outlined below.

Solar panel workmanship/materials/product warranty

As solar panels contain no moving parts, barring hail, tornadoes, and children throwing rocks, they are probably the least likely part of your solar photovoltaic system to give you problems, even in the long run. Just in case something does go wrong, though, there is a workmanship warranty.

A workmanship warranty, sometimes called a materials or product warranty, is usually valid for anywhere from 1 to 10 years, and will cover the components that make up your system’s panels: the glass, laminate, backing, and possibly the silicon cells/wafers contained within. Damage to these parts of the panel, although unlikely, may result in major or minor losses to their electricity production capacity. These warranties exist just in case something untoward does somehow befall your panels.

Some important things to consider and questions to ask:

-Is the materials warranty from the panel manufacturer or your system installer? If it is the manufacturer, make sure you know if you will have to send your panels overseas to have them serviced in the case of damage or problems. Is this something you are prepared to do? Will you have to pay to have them shipped?

-Are there any contractual requirements for regular maintenance of the panels, which if not undertaken could void your warranty? If so, what are they? How much will they cost to undertake?

-Who is the manufacturer/installer? How long have they been in business? Are they reputable?

Manufacturer’s power output / performance warranty for solar panel silicon wafers

Generally speaking, the silicon wafers (encased in glass in your solar panels) will be the most durable, long-lived part of any panels that you ultimately purchase–provided there are no incidents that damage them. For this reason, power output warranties (also called performance warranties) ordinarily last between 25 and 35 years.

Performance output warranties will cover repairs for the silicon cells/wafers themselves, should their electricity production fall below a predetermined percentage of the panels’ rated capacity. For instance, you would be covered in the case that your array output falls below 80% and the drop is due to a defect in the cells themselves (not due to a fault of the rest of the system, known as Balance of System or BoS). Some output warranties may also be graduated, e.g. 90% of rated performance efficiency at year 15, 80% performance efficiency at year 35, etc. The fact is, though, that panels may continue to produce electricity even after the warranty has expired, possibly at a rate very close to the system’s nominal capacity.

Some important things to consider and questions to ask:

-Is your output problem really an issue with your panels’ productivity, and not the BoS? How is panel performance measured? Keep in mind that the output of your system as a whole may be less than optimal even if your panels are performing at their rated capacity.

-Is the performance warranty through the manufacturer or through your installer? Will you have to send your panels overseas to have them serviced if something goes awry?

Other solar power-related warranties

Inverter manufacturer’s warranties:

A warranty for your inverter is absolutely critical. Inverter warranties typically last for 5 to 10 years, although your installer may also offer extended warranties on request. Your inverter is one of the most important parts of any solar power system; it is also one of the most expensive, and one of the most prone to malfunction, thanks to the fact that it is constantly working to convert the DC power from your panels to the AC power required by your appliances and the grid: if your inverter breaks down, your system will essentially stop working! The first thing to do is make sure that you have selected the right inverter for your system size, and then check the reputability of the manufacturer and the model; installing a wrongly-sized inverter could void the inverter warranty.

Battery warranties:

If you have a stand-alone system or a hybrid system, it will include batteries, which typically have warranties of 5-10 years. Batteries, as we have discussed previously, can be the most maintenance-intensive and expensive parts of a stand-alone power system. Be sure that you understand the maintenance requirements to ensure that you are in compliance with your battery bank’s warranty conditions.

Balance of system warrantees:

Your installer may also warranty for the balance-of-system (non-panel components of your system) in order to cover miscellaneous issues with your system, such as wiring, inverter, and batteries. Ask the installer about what is on offer.

Written by James Martin

Solar Choice Analyst

© 2011 Solar Choice Pty Ltd

Sources and Links:

Previous related Solar Choice blog entries: How solar energy works : Troubleshooting your grid-connected solar power system : Optimising your system through inverter sizing : Oversizing your inverter for future system expansion : Stand-alone system batteries : Accredited solar power system components and installers

James Martin II

James Martin II

Communications Manager at Solar Choice
James has been Solar Choice's primary writer & researcher since 2010. He lives in Newcastle in a house with a weird solar system.
James Martin II

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