Installing a solar system is a long-term investment that can provide significant savings and sustainable energy. However, the key to successful implementation is precise planning and preparation – including the creation of appropriate connection points, assessment of shading conditions, selection of the right technology, and the use of premium-quality equipment. In this article, we have collected the most common installation and operation errors – at each point, we present the consequences of the error and provide a solution proposal to prevent it. This way, you can avoid common pitfalls and ensure that your solar system operates efficiently and safely in the long term.
1. Choosing an unreliable contractor (lack of expertise)
One of the most serious mistakes is to entrust the design and installation of a solar system to a contractor who is not fully qualified. The work of an inexperienced or unqualified installer can lead to additional costs and even create a life-threatening or fire-threatening situation. For example, faulty electrical connections or poor mounting can cause serious damage to the system, even millions of damage simply due to incompetence. It is important to know that although legally it is sufficient for an electrician to carry out the installation, in practice a well-functioning solar system requires a well-trained, multi-professional team (electrician, carpenter, roof specialist, etc.), since installation is a complex process consisting of several phases.
Consequence: Mistakes made by an unqualified contractor can result in an inefficient or dangerous system. In the worst case scenario, an electrical fire or accident can occur if the system is not installed properly.
Solution/Tip: Always choose a reliable professional with references to install the solar panel. Check that the contractor has the necessary electrical qualifications and experience, and whether he offers a guarantee for the work. It is worth asking for recommendations and looking at previous projects. Don't waste time choosing the right partner - the precise work of a professional team is the basis for the safe operation of the system for 30+ years.
2. Using cheap, low-quality equipment (excessive savings)
Many people make the mistake of choosing solar equipment (panels, inverter, mounting structure) based on the lowest price, or accepting the cheapest offer. However, excessive savings can quickly backfire in this industry. Using poor-quality panels or inverters will result in lower system efficiency, more frequent failures, and a shorter lifespan. For example, a cheap mounting structure can start to rust within a few years, jeopardizing the fastening of the panels and thus the integrity of the entire system. Similarly, cheaper inverters can also break down faster, so in the long run it is better to choose quality equipment.
Consequence: Poor quality devices can reduce production and require more frequent maintenance or replacement. The payback period of the system is extended, as lost production and additional repairs mean additional costs. In extreme cases, the failure of a weak inverter can cause the entire system to shut down.
Solution/Tip: Don't just base your decision on price! Choose premium quality panels, inverters, and mounting structures, even if they seem more expensive at first. High-quality solar panels are designed to last 30-40 years, so the mounting structure should last at least that long. Look for a contractor who guarantees that all components are of the right quality and provides a full range of services from design to permitting to installation. A higher quality system is more profitable in the long run because it produces more stable power and generates fewer errors.
3. Inadequate sizing (under- or over-designed system)
A common mistake is to missize the system, i.e. if the performance is underestimated or overestimated. An undersized system will not produce enough energy, so it will not fully cover consumption, and the owner will not achieve the desired savings. On the other hand, an oversized system can be unnecessarily expensive: the excess energy produced cannot always be utilized or fed back into the grid, so the return on investment is significantly slower. For example, if someone installs a capacity much larger than their needs, some of the panels may remain unused, especially if the feed-back to the grid is limited.
Consequence: In case of undersizing, the electricity bill may remain high because the solar system does not produce enough. In case of oversizing, the investment cost is unreasonably high, which does not pay off within a reasonable time. In both cases, the economy of the system deteriorates.
Solution/Tip: Conduct a thorough needs assessment and planning with the help of a professional. Collect annual energy consumption data and calculate the optimal system capacity based on this. Also consider future energy needs – for example, are you planning to use electric heating, air conditioning or electric car charging in the future? For accurate planning, you can use software sizing tools or the expertise of installers. The performance of a well-sized system covers the consumption, but does not exceed it by much, so that the investment is utilized in the best possible way.
4. Wrong orientation and tilt angle
When placing solar panels, it is critical to set the correct orientation (direction) and tilt angle. In Hungary, the most ideal orientation is towards the south, with an inclination angle of approximately 20–40°. If the roof orientation differs significantly from this, the performance of the solar panels may decrease noticeably. For example, in the case of a purely eastern or western orientation, the production may be up to ~15% lower compared to the southern direction. On a roof that is too steep, the panels receive less perpendicular sunlight, and in the case of a flat angle, dirt can accumulate on them more easily. In addition, if the modules are connected in a string, all panels must be on a surface with the same orientation and tilt angle - otherwise, due to the difference, one panel may reduce the performance of the other.
Consequence: In case of non-optimal orientation/tilt angle, the system will not achieve the planned yield. Due to the lower production, the payback is postponed. In extreme cases (e.g. a completely north-facing roof), the investment may even become uneconomical because the solar panels do not receive enough sunlight.
Solution/Tip: Aim for a southerly orientation and a tilt angle of ~30°, as far as the location allows. If the orientation of the roof is not ideal, consider alternative placement of the solar panels: for example, on a ground-mounted support structure or on the roof of an outbuilding. With the involvement of an expert, it is possible to accurately assess the characteristics of the roof (even with 3D drone footage to analyze the angle of the roof plane and shadow effects). The system can also be installed with a slight east/west orientation, but in this case the installer may recommend performance optimizers or other technical solutions to minimize losses. The main thing is that the panels receive sunlight at the right angle all day long, as this ensures the best efficiency.
5. Ignore shading
Shadow is one of the biggest enemies of solar systems. A common mistake is not paying enough attention to where and when the panels are shadowed during installation. Even a small shadow spot – the shadow of a tree branch, chimney or antenna – can cause a disproportionately large loss of yield. In traditional string-connected systems, if the performance of one panel drops due to shadow, it degrades the performance of the entire panel row (string). In addition, permanent shading can also result in hot spots in the cells: in this case, the solar panel in the shadow acts as a cell resistor, overheats, and the heat can damage the cell (causing discoloration and damage). This not only means less energy production, but can also shorten the lifespan of the panel.
Consequence: In case of shading, the efficiency of the system can decrease dramatically – even a single shaded cell can cause a 20-30% loss of production for the entire panel. In the long term, hot spots due to shading can damage the modules, which may require replacement. Unexpected shading reduces the return on investment, as the system does not produce the calculated energy production.
Solution/Tip: Conduct a thorough shadow analysis during the design phase. Before installation, have a professional assess when the roof is shaded during the year (according to the Sun's path). Avoid placing the panels in a location where tall trees or buildings cast shadows nearby. If some shadow is unavoidable, consider using power optimizers or micro-inverters - these manage the power per panel, thus reducing the effect of shadow. In addition, eliminate any shadow-causing landmarks (tree branches, antennas, etc.) by pruning or moving them. During system operation, also monitor whether any trees or buildings have grown over the years that cast new shadows; if so, deal with the problem (cutting branches, moving panels). Goal: the panels receive as much direct sunlight as possible throughout the year.
6. Ignoring future expandability
Sometimes, when designing a system, we don’t think about future needs or expansion options. For example, we don’t have an electric car or battery today, but in a few years we might want to integrate them into our household energy supply. If we don’t take these future plans into account when building a solar system, we may encounter difficulties later: the inverter may not support additional solar panels or batteries, or the grid connection capacity may become a bottleneck.
Consequence: We have to make compromises or additional costs when expanding later. For example, if we want to connect a battery later, but our inverter is not a hybrid type, then the inverter will need to be replaced. Or if the original system covered the old consumption, but in the meantime we have installed a heat pump or started charging an electric car, the existing capacity is no longer sufficient, and obtaining permission and implementing the expansion will be an additional task. In short: it is much more difficult and costly to adapt the system to new needs later.
Solution/Tip: Think ahead about your expected future energy needs. Let the contractor know during the planning process if you want to expand the system later or if you are planning a battery energy storage system (hybrid system). Nowadays, the price of batteries is decreasing, so hybrid systems are becoming more and more economical - it may be worth choosing an inverter that can be supplemented with a battery later. If consumption is expected to increase (e.g. due to charging an electric car or new electrical equipment), incorporate this into the sizing: install a slightly larger inverter or leave space for additional panels on the roof. With smart planning, the system can be flexibly developed and keeps up with changing needs.
7. Failure to comply with permits and regulations
Many people do not take into account that the installation of solar systems is regulated by law, and in some cases, the construction requires a permit. In Hungary, a building permit is required for systems over 50 kVA (50,000 W). But even for smaller, household-sized power plants, the connection to the grid must be approved by the electricity supplier if a regenerative (grid inverter) system is installed. A common mistake is that the owner only starts to arrange the permits afterwards or does not report the system at all - this can cause serious inconvenience. The processing time for the electricity supplier's permit can be several weeks or months (the process from the application to the installation of the replacement meter can take up to 2-3 months), so if someone skips this or starts late, the system, even though it is ready, cannot be turned on in time.
Consequence: In the case of an unlicensed or unreported system, we can expect penalties, chargebacks, and the service provider may cut off the supply due to the electricity illegally generated on the network. In extreme cases, the service provider may have the system dismantled due to the illegal connection. But even if we allow it, the completed solar system may remain unused for months due to the late request for meter replacement. This causes a loss of income (since we will still be paying the electricity bill, instead of the solar panel producing).
Solution/Tip: Follow the rules and get the permits in time. Before installing the system, find out about the current regulations. If you are planning a larger system (over 50 kVA), obtain a building permit before construction. In the case of a grid-fed system, submit the request for connection to the service provider during the design phase - this way, the permit can run in parallel with the construction. Do not wait until the system is built, because the paperwork can take a long time. Coordinate with the contractor: most companies will also help with the administration. If all permits are in order, we will avoid legal problems and the system can be put into operation immediately as soon as it is completed.
8. Neglect of operational safety and protection
A well-designed solar system can provide electricity to the entire house, so safety solutions are essential. Two areas of particular importance are touch protection and surge protection. A common mistake is not to install proper grounding, disconnect switches, and surge arresters during installation. However, the lack of these poses a serious risk. Without touch protection, a possible insulation fault can cause an electric shock to anyone who touches the system (even causing a fatal accident). Without surge protection, a lightning strike or a power surge can destroy the electrical equipment in the house and the components of the solar system.
Consequence: Lack of safety protection can lead to life-threatening situations and material damage. In the event of a major surge, the inverter or the house's electrical network can burn out, which is very expensive to repair. In addition, the insurance company may refuse to pay compensation if it turns out that standard protection was not installed.
Solution/Tip: Never skimp on safety equipment! Make sure the contractor installs standard grounding, surge arresters and appropriate circuit breakers. Ask for documentation that the contact protection measurement has been completed and the system complies with electrical standards. If a battery is part of the system, it should also have adequate fuses and heat/smoke detector protection. Both external lightning protection (arrestor) and internal surge arresters are recommended against overvoltage. These precautions represent minimal additional costs compared to the entire investment, but they protect human life and property from unexpected events.
9. Incorrect placement of the inverter
The inverter is the heart of the solar system: it converts the direct current produced by the panels into alternating current, and also performs a number of protection and data collection functions. It is very important that the inverter is placed in the right environment. A common mistake is to install the inverter in an unfavorable location – for example, in the blazing sun, on an external wall exposed to rain, or in a closed, unventilated attic where the summer can reach 60°C. Non-ideal placement **reduces the efficiency of the system and can even lead to premature failure of the device】. A solar inverter, if it operates in an environment that is too hot, cuts its power (backload) to protect itself – thus reducing production. And if it is constantly exposed to moisture or dust, the electrical components will be damaged.
Consequence: If the inverter is placed in the wrong place, the system will not be able to deliver its maximum output, especially on hot days. The lifespan of the inverter may be shortened, and errors may occur more frequently (e.g., overheating shutdown). In extreme cases, a wet or overheated inverter will be completely destroyed, requiring expensive replacement equipment.
Solution/Tip: Pay attention to the optimal placement of the inverter. It should be placed indoors, preferably in a cool, dry place (e.g. on the wall of a mechanical room or garage), where it is not exposed to direct sunlight or precipitation. If it must be placed outdoors, choose an inverter with a weatherproof cover, but it is still advisable to find a shaded, well-ventilated place for it. Do not place it in dusty, hot attics, but rather place it in a cooler part of the house. Ask a specialist for advice on the installation location - professional installers know exactly where to place the inverter for a long service life and good efficiency. A well-placed inverter will do its job quietly, reliably, and will not require unexpected service.
10. Errors in establishing a network connection
When installing a solar system, the correct design of the network connection point is also critical. A typical mistake that is only discovered during construction: there is not enough space in the house's electrical distribution board to connect the solar system, or only the sealed connection point is accessible at the meter. In such cases, the distribution box must be expanded later or the meter must be relocated, which causes a loss of time and money. Another common problem is ignoring the phases: even though the building's main line is three-phase, if only one phase is connected to the distribution board - this way, it may be discovered later that the installed 3-phase inverter cannot be connected to the existing network. This again requires extra work (network expansion, connection of 3 phases).
Consequence: Incorrect connection means delays and additional costs in the project. Expanding the distribution board or converting the metering point can be an unexpected expense of tens of thousands of forints and requires a specialist. If the number of phases of the inverter is wrong, either the entire inverter must be replaced with the correct type or the phase extension must be arranged with the electricity supplier – both are tricky and time-consuming. In addition, until the network connection is resolved, the system cannot operate, so the owner suffers a loss.
Solution/Tip: Before installation, consult an electrician about the network connection. Check the main distribution cabinet: is there room for the switches and circuit breakers of the solar panel system? If not, plan the expansion in time. Check the number of phases and their load capacity: a maximum of ~5 kW inverter can be connected to a single-phase network; if you want a larger system, it is worth building a three-phase connection. Consult the electricity supplier in advance about the connection points - they will tell you what needs to be created (e.g. a separate metering cabinet). Also involve the contractor: an experienced company will check these details during the survey and make suggestions if any modifications are needed. This will avoid any shortcomings being discovered during installation.
11. Construction errors when installing panels
Even with good planning and permits, physical construction errors can occur during installation if installers do not work precisely. One such error is when the panels overhang the edge or ridge of the roof. This should be avoided at all costs, as a strong wind can catch on the overhanging panels and tear them off the roof, even damaging the roof sheathing. Another common problem is when the panels are installed too tightly together, without an expansion gap. Natural expansion due to temperature changes requires space - if there is no space, the cells can strain against each other and crack, which leads to a significant loss of performance and shortens the life of the panels. It is also important to ensure that there is an adequate air gap between the roof and the panels for rear ventilation; the lack of this can lead to overheating and loss of efficiency. Signs of sloppy construction can also include messy cabling, loose screws, and non-waterproof junction boxes – all of which should be avoided.
Consequence: Installation errors can lead to system failure or reduced performance. Poorly installed panels can be subject to storm damage. Cracked solar cells permanently lose some of their performance and may need to be replaced prematurely. Unventilated panels overheat, which reduces the efficiency of the cells and accelerates their aging. Overall, a poorly installed system will not produce the expected production and will require more maintenance.
Solution/Tip: Choose an experienced, precise contractor who adheres to installation guidelines and standards. At the end of the installation, visually check the work: the panels are installed parallel, flush with the roof plane, and do not hang too much anywhere. Make sure that there is a gap of a few centimeters between the panels and an adequate distance from the roof to the frame (for ventilation). Ask the contractor for technical documentation on the fastenings and electrical connections. A quality contractor will ensure that every screw is tightened, every cable is fixed and UV-resistant, and every connection is waterproof. If possible, ask for a guarantee for the installation work – so that if something goes wrong later, you will have someone to turn to.
12. Lack of system monitoring
Many users make the mistake of leaving the system alone after installing a solar system and not monitoring its performance. In the past, it may have been difficult to track production, but most modern inverters today have an internet connection and a mobile application. With these, we can check the current production from anywhere, at any time, and receive daily, monthly, and annual reports. If we do not have an overview of the system's operation, it is easy to not notice for weeks or months if the system's performance has decreased due to a fault (for example, a fuse has blown, the inverter has stopped, or simply partial shade reduces the yield).
Consequence: Without supervision, the solar system may not produce or only operate in reduced mode, and the owner may not know about it. During this time, the lost production is a financial loss. In addition, minor errors can turn into bigger problems: for example, an intermittent inverter tripping may indicate a problem with the electrical network, which if not remedied, can cause a more serious failure.
Solution/Tip: Take advantage of the monitoring options! Set up the inverter’s online monitoring or smartphone app and check the production data regularly. It is worth checking, say, weekly, whether the daily production is as expected (e.g. high on clear days, lower on cloudy days). Many systems can be set to send an alarm/email notification in case the inverter detects an error or production drops significantly – take advantage of these features. If you see anything unusual or suspicious (e.g. one solar string produces half as much as the other, or there is a big drop compared to the same period last year), have the matter investigated immediately. Continuous monitoring allows you to intervene in time, thus ensuring the long-term optimal operation of the system.
13. Failure to maintain
Solar systems are often described as “maintenance-free,” but that doesn’t mean you should never take care of them. Although there are very few moving parts (the panels have practically none), it is worth checking and cleaning certain components from time to time. A typical mistake is that the owner doesn’t even look at the system for years. This way, they don’t notice if, for example, a fastener has become loose, a cable tie has become worn out, or moss has grown on the edges of the panels. Without maintenance, minor problems and dirt can add up, and the system’s performance gradually decreases over time. They often only notice when there is a more serious problem (e.g. the inverter stops due to water).
Consequence: A solar park left without regular maintenance will not provide optimal performance in the long term. Energy production is reduced due to the shading effect of accumulated dirt or leaves. If a panel moves due to a loose mounting element, it can eventually be torn out of place in high winds. Unchecked electrical connections can heat up, which can also pose a fire hazard. Overall, a neglected system has a shorter lifespan and is more likely to fail.
Solution/Tip: Establish a basic maintenance routine. Inspect the system at least once a year (but preferably twice, in spring and autumn) or have it done by a professional. During maintenance, clean the surface of the panels (if necessary) and visually inspect all important elements. Check the screws of the support structure, the integrity of the panels (no cracks, loose frames), the insulation of the wires and connections. Note if any changes have been made to the system and document the errors and repairs experienced (this way the system status can be tracked). Monitor the yields on a monthly basis and if anything is noticeably low or unusual, find out the reason. As part of maintenance, remove newly grown plants that provide shade from near the system (e.g. prune back trees). It is worth having your panels tested for performance and thermal imaging every 3-4 years to detect any cell degradation in time. Regular maintenance ensures that your solar panels will be in top shape for decades with minimal effort.
14. Improper cleaning of solar panels
There are many misconceptions about cleaning solar panels. Many people think that panels need to be washed manually at certain intervals, and this is done at home. In reality, this can do more harm than good to the panels. Dust and dirt do cause some (usually minimal, a few percent) loss of performance, but this is usually washed away by rain from time to time. Rough rubbing or the use of inappropriate chemicals can damage the surface of the panels (the glass and the anti-reflective coating). In particular, it is forbidden to spray hot solar panels with tap water - cold water causes heat stress, and minerals dissolved in water will settle and damage the equipment. A typical mistake is, for example, to start scrubbing the panels on the roof with a slag or a hard brush, which can cause scratches and micro-damages.
Consequence: Improper cleaning can cause permanent damage to the modules. A scratched or chemically stained surface allows less light to pass through, reducing performance. Untreated tap water can leave limescale stains, which also reduces light transmission. In extreme cases, the glass can crack due to sudden cooling. In addition, cleaning on the roof can be dangerous without the right equipment.
Solution/Tip: We basically leave the cleaning of solar panels to nature. Under normal circumstances, rain will clean the panels, washing away most of the dust on them. We should only clean them if it is really necessary – for example, if the panel is covered in thicker dirt or bird droppings that the rain has not removed. In such cases, we should use gentle methods: rinse with a soft sponge or brush, lukewarm, preferably deionized/distilled water, and only in the early morning or late afternoon, when the panels are not hot. Do not use aggressive chemicals. If you want to be on the safe side, call a professional cleaning team who will clean the panels safely with special tools. It is important to emphasize that we will not gain more proportionally by cleaning them too frequently: a possible gain of a few percent may not be worth the effort and risk. Instead, pay attention to the other elements of the system (e.g., dusting the inverter's cooling fins if it's outdoors - but only according to the manufacturer's instructions). In summary: the cleanliness of solar panels is important, but sometimes less is more - just touch them carefully and rarely.
15. Lack of solar system insurance
After successfully installing a solar system, many people think that they have done their job. However, one important step may be missed: properly securing the system. Solar panels are exposed to the elements – think of hail, a tree falling due to a strong storm, or even a lightning strike. These are unexpected events that can cause serious damage to the equipment, and unfortunately, they cannot always be avoided even with the most careful operation. If we do not have insurance, in the event of major damage, we will have to finance the repair or replacement ourselves, which can cost hundreds of thousands of forints.
Consequence: Without insurance, a damage event (e.g. hail, fire, theft) can cause significant financial losses to the owner of the solar panel. It may happen that the system is out of order for months due to a broken inverter or broken panels, and all this has to be fixed out of pocket. This also delays the return on investment, as you have to pay for repairs and replacement panels again.
Solution/Tip: Take out insurance specifically for the solar system. Many home insurance policies do not cover solar damage as a standard or only partially, so it is worth asking about it and taking out additional insurance if necessary. There are also insurance products specifically for solar panels. The ideal is for the insurance to be valid from the day the installation is completed - so you are protected from the very first moment. In fact, some insurers offer construction and installation (CAR) insurance for the construction period, which covers damage that occurs during installation (e.g. falling panels, damage during installation). Solar panel insurance costs only a fraction of the value of the system per year, but it gives you peace of mind that your investment will not be lost in the event of unexpected damage. Look into the options available on the market and choose insurance that provides coverage for the most important risks (ice damage, lightning damage, fire, theft, storm damage, etc.).
Summary: By avoiding the above mistakes, your solar system will operate safely and efficiently in the long term. Whether it's planning, installation or operation, pay attention to detail at every stage. The following checklist summarizes the most important tips for avoiding common mistakes:
By following the above points, the installation and operation of your solar system will be smooth. Remember: a solar system is a long-term investment that pays off best when it is professionally installed and carefully maintained.
This way, your solar panels will serve you safely for decades, and you can maximize the energy savings you can achieve while avoiding costly mistakes and inconveniences.
