Safety in photovoltaic installations: what are the main mistakes made?

Safety in solar energy installations is a very important aspect when validating a project and should be the number one concern for all integrators operating in the market.

However, due to the rapid growth of the sector, many unprepared professionals and companies end up emerging and offering poor quality services, putting the client's investment at risk.

Bruno Kikumoto, electrical engineer and director of Canal Solar, listed during what he considers to be the top ten mistakes made.

Before mentioning them, however, he highlights a few important points: the first concerns the technical standards for each type of project. "If their concepts were applied, most of the problems wouldn't even occur," he assured.

"The standard is not a law, meaning it is not legislative in nature. However, if a company ends up in a legal dispute, a strong argument for the judge to rule on is whether or not the design and execution comply with the technical standards," he emphasized.

The second point mentioned concerns the technical responsibility of projects—who can and cannot sign off on the installation of a solar energy system. According to him, this role falls to electrical engineers and, depending on the power level, to electrical technicians.

Check out below the ten most common mistakes that end up being made by companies and professionals in the solar energy sector, in the opinion of the director of Canal Solar.

Cable sizing

Undersizing, routing and connections that do not comply with standards, manufacturer specifications and basic engineering concepts can cause inverter shutdown problems at times of peak solar availability.

“Many designers sometimes think there is an internal problem with the inverter because it shuts down during peak generation periods, when in fact the vast majority of problems are caused by poorly sized conductors,” said Kikumoto.

Connectors and crimping

Electric arcs caused by poor contact in connectors are among the main causes of failures in the installation of a photovoltaic system. 

To ensure a good electrical connection, it is necessary to follow the recommendations regarding the maximum size of the bare conductor that fits into the terminal and also the correct use of the crimping tool for conductor termination.

Torque in connections

If the recommendations contained in the manufacturers' manuals (inverters, circuit breakers, among others), the use of correct tools and the technical standards on the subject are not followed, problems such as the interruption of the operation of a solar power plant may occur. 

“When I give my lectures, I always ask how many participants use a torque wrench to check electrical connections. Few mention having the equipment (…) Unfortunately, human error happens and for this we have to use the appropriate tools,” he said. 

Stepping on photovoltaic modules

Solar panels are designed to withstand harsh weather conditions such as rain, hail, snow, and wind, but they are not designed to support the weight of people. "If a cell cracks, there will be no electrical current flowing through this discontinuity, impacting the photovoltaic module's generation and the investor's expectations regarding the project's efficiency. Furthermore, it can cause hot spots in these cells, causing them to degrade rapidly and potentially even leading to fires."

Improvised structures

Photovoltaic systems must be designed to meet manufacturer specifications and tested in adverse weather conditions to ensure there will be no problems for the customer.

For example, you cannot use fastening structures, such as parts or screws, that were not designed for that purpose. “In the first instance of a stronger gust of wind, this structure could probably come loose.” 

Orientation and tilt “corrections”

In the southern hemisphere, where Brazil is located, photovoltaic modules generate better energy when installed facing north and with an inclination angle equal to the latitude of the location in which they are located.

The problem here is that few roofs have this configuration, and in an attempt to “correct” these two factors, many integrators reposition the modules incorrectly, causing problems from a mechanical point of view and a negative aesthetic influence on the construction, as in the image below:

In these cases, maintaining the modules in the same orientation and roof pitch is generally the best design option. To compensate for the lack of tilt or suboptimal azimuth, one can consider adding more PV modules to achieve the expected energy production.

Collapse in roofs

Although it is not very common, problems related to roofs, especially metal ones, that cannot support the additional load of photovoltaic modules still occur in the country.

These errors tend to occur more frequently in commercial establishments that do not have well-distributed walls and support pillars, such as a residence, for example. 

“This is because this type of structure is often designed to support its own weight and wind loads, but not to support additional loads.”

In these projects, it's best for a competent professional (a civil engineer, for example) to assess and determine whether the structure can support the additional weight of the system that will be installed on site. This professional should also present the technical report and the ART (Technical Responsibility Note). 

Installations with shadows

Installing photovoltaic modules in shaded areas is not always avoidable, but it is necessary to optimize the allocation of photovoltaic modules so that they are only in the shade during periods of low generation, which would be at the beginning or end of the day.  

The image below shows a solar power system installed in an area with no solar radiation at around 11:00 a.m. This means that, during the peak solar radiation hours, there was no generation of solar energy, as the photovoltaic modules were completely shaded. 

However, it's not just total shadows that end up being a problem, as there are cases of projects installed in locations that present occasional shadows throughout the day. 

This is also a problem, as this type of shade often prevents the bypass diodes from activating, causing hotspots in the cells. This causes the cells to degrade more quickly, potentially causing a fire in extreme cases.  

"It's a fairly common problem we see, especially in ground-based projects, where tall vegetation above the module planes creates this type of shade. Proper operation and maintenance could prevent this."

String parallelization

When you want to parallelize strings of photovoltaic modules, you need to analyze and ensure that you have the same open circuit voltage between these strings, otherwise fires may occur in installations.   

According to Kikumoto, to avoid these problems it is necessary to work with strings that contain photovoltaic modules of the same model, the same manufacturer and the same quantity.  

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