Do livestock buildings need ammonia-resistant solar panels?

A poultry house, a pig unit or a cubicle shed is one of the more hostile places a solar module can spend thirty years. The question is whether that needs a different panel, and the answer is that it needs a tested one. This post sets out the test, who runs it and how to ask for it. It is the research behind the solar panel comparison for farm roofs.

The problem: ammonia and the module’s metalwork

Livestock buildings breathe out ammonia from slurry, bedding and sprays, and the air leaving a ventilation outlet carries it onto whatever sits above. TUV Rheinland, which certifies modules against the test, describes the case directly: systems used in agricultural environments, for example on the roofs of livestock buildings, can be tested for corrosion from the ammonia present in sprays and liquid manure. The parts at risk are the frame, the glass coating, the junction box and the connectors, and the consequence of corrosion is a module that leaks, loses output or arcs.

The test: IEC 62716

IEC 62716:2013 is the ammonia corrosion test for flat-plate PV modules. As TUV Rheinland sets it out, the corrosion test comprises 20 test cycles, each of 24 hours, for a total of 480 hours, or 20 days. To pass, the modules must show no obvious visual defects and no more than a 5% drop in maximum output. It is a type test on the module design, so the certificate is for a specific model, not a brand.

Two things follow for a farm buyer. First, the certificate has to match the model number on the quote; a brand that holds the certificate on one range does not hold it on all of them. Second, the test is not part of the standard IEC 61215 and 61730 certification every module carries, so its absence from a datasheet is not an oversight, it is information.

The coastal cousin: IEC 61701

Farms within reach of sea spray have a second test to ask about. IEC 61701:2020 is the salt-mist corrosion test. In TUV Rheinland’s description the test comprises eight cycles of seven days, 56 days in all, with the same pass criteria: no obvious visual defects and no more than a 5% drop in maximum output. Much of the Welsh, Cornish, Scottish and East Anglian coastline is within reach of salt-laden wind, and a module that has passed only the ammonia test is not the right answer on a cliff-top dairy.

Where on the farm it matters most

The exposure is highest where the air leaving the building is concentrated: around ridge and gable ventilation outlets, above fan housings and on roofs directly over slatted or deep-litter areas. An array on a machinery store across the yard has a different exposure from one on the finishing shed, and the specification can differ building by building. An honest installer will say so rather than specify one module for the whole holding.

How to ask for it

1. Put the exact module model number on the quote, not the brand.
2. Ask for the IEC 62716 certificate for that model where the roof is over livestock, and the IEC 61701 certificate where the farm is coastal.
3. Ask who issued it. TUV Rheinland is one certifier; others exist, and the certificate names the lab.
4. Keep the certificate with the handover documents, because a corrosion-related warranty claim will turn on it.

The ammonia and salt-mist certificates are two of the five tests set out on the solar panel comparison for farm roofs, alongside the independent reliability results, the mechanical build for an exposed roof and the warranty wording. The building types where the ammonia question arises are covered on solar panels for farm buildings.

Corrosion is one reason a livestock-building array ages faster than the averages suggest; the general degradation figures are in how long solar panels last on a farm roof.