Buying a photovoltaic system – What property owners should watch out for

More and more homeowners are considering installing a photovoltaic system. No wonder, as it enables them to generate eco-friendly electricity for their own use and also brings financial savings through feeding power into the public grid. But what should you, as a property owner, watch out for when planning the purchase of a photovoltaic system? In this article, you will learn the most important aspects for your decision.

Preliminary checks: Is my roof suitable at all?

Before deciding on an offer, you should clarify whether the installation of a photovoltaic system on your roof is even possible. Important factors include the orientation and pitch of the roof as well as potential shading from trees or other buildings. It is best to obtain an assessment from a specialist company or energy consultant for this. The structural integrity of the roof should also be checked, as modules and substructures carry a significant amount of weight. If the basic prerequisites are met, there are various options for mounting a PV system on the roof.

Determining the right size for your photovoltaic system

When planning the optimal system size, you should consider the following aspects:

The larger the photovoltaic system, the lower the costs per kilowatt of output usually are. The reason for this is the fixed costs, such as for installation, which are incurred regardless of the system size. When sizing the system, use the available space on your roof and your household electricity consumption as a guide.

Also consider the future purchase of an electric car. With a larger PV system, its battery could be conveniently charged at home. However, a very large system also means that you have to feed some of the electricity into the public grid at a comparatively low tariff.

One option is to install two separate photovoltaic systems on your roof. A smaller one supplies only your own consumption, while the larger one serves exclusively as a feed-in system. You will receive a higher remuneration for the electricity fed into the grid. In this case, however, inform your grid operator so that they can correctly register the systems.

Last but not least: PV systems with an output of 25 kilowatts or more must be remotely controllable. The grid operator can then throttle the feed-in to keep the power grid stable.

Calculate the profitability of the photovoltaic system

A crucial question is whether investing in a photovoltaic system will pay off for you financially. Various factors come into play here: the investment costs consist of the modules, inverter, substructure, and installation. Added to this are ongoing costs for maintenance and insurance. Offsetting this are your potential savings: you use part of the generated electricity yourself, thus saving on your previous electricity costs. You can feed the rest into the public grid for a feed-in tariff. Also, factor potential subsidies into your calculation. This makes it possible to determine the payback period. Under good conditions, this is currently in the range of 10 to 15 years.

The various components of the photovoltaic system

When choosing the components, there are various aspects to consider. Photovoltaic modules convert sunlight into direct current. Here, crystalline solar cells have predominantly established themselves, which are divided into monocrystalline and polycrystalline. Both types are well suited for roof-mounted systems. The inverter then converts the direct current into grid-compatible alternating current. Make sure here that the efficiency is over 98 %. For the substructure, simple installation and good rear ventilation are primarily important. The connection to the power grid is usually made via a two-way meter.

Now or later: When does a battery storage system make sense for your photovoltaic system?

A battery storage system enables a more efficient use of solar power. Whether it is economically viable depends on its cost and durability. A storage system for 15 years of use should not exceed 600 euros per kilowatt-hour.

Storage prices could fall in the future. The Fraunhofer Institute forecasts a 20 percent price reduction by 2030. For 10 kWh models, this corresponds to savings of approximately 2,000 EUR.

There are no disadvantages to buying later. If a storage system is added later, it is subject to the exact same VAT exemption as a direct purchase with a PV system. However, if a later integration is planned, a hybrid inverter should be considered during the initial installation of the PV system to avoid additional costs.

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Compare offers and find the best provider

It is recommended to obtain quotes from at least three regional providers. When doing so, compare the products and services offered in terms of prices, conditions, and, if applicable, service. It is also important that the provider has references for projects already carried out. In addition, pay attention to certifications and memberships in trade associations. With the best offer, you will have a solid foundation for your investment.

From price to performance: What should be included in your offer

A comprehensive quote for a solar system should cover every cost item, from materials, scaffolding setup, and module installation to the complete electrical connection and any new meter cabinet that may be required. A detailed price per item makes it easier to compare quotes, even though this is not always standard in the industry.

Furthermore, the offering should comply with two essential standards: VDE-AR-N 4105, which regulates installation and connection details, and DIN EN 62446, which determines the necessary checks during commissioning as well as the required customer documents.

The contract and the installation of the PV system

Once you have decided on an offer, a contract for the delivery and installation is concluded. A maintenance contract is important, which ensures the regular inspection and maintenance of the system. During installation, electrical engineering regulations and the grid operator's specifications must be observed. After commissioning, the system must be registered with the grid operator and the Federal Network Agency.

From price to performance: What should be included in your offer

A comprehensive offer for a solar system should cover every cost item, from the materials, scaffolding setup, and module installation to the complete electrical connection and any new meter cabinet that may be required. A detailed price per item makes it easier to compare offers, even if this is not always standard in the industry. Furthermore, the offer should comply with two essential standards: VDE-AR-N 4105, which regulates installation and connection details, and DIN EN 62446, which determines the necessary inspections during commissioning as well as the required customer documents.

Prepared for the project: Questions before purchasing and installing a photovoltaic system

Before property owners buy a photovoltaic system, they should ask a series of questions to ensure that the system meets their needs and represents a profitable investment. Here are some essential questions that property owners should consider before acquiring a photovoltaic system:

• Site suitability: How suitable is my roof or property for a PV system regarding orientation, pitch, and shading?
• System size: What size and capacity should my system have to cover my annual electricity consumption?
• Costs and Profitability: What does the cost-benefit analysis look like? When will I reach the break-even point? What government subsidies or tax benefits can I claim?
• Technology and Quality: Which technology (e.g., monocrystalline, polycrystalline) is best suited for me? What about the quality and lifespan of the proposed modules and inverters?
• Storage options: Should I consider a battery storage system? How would this affect profitability?
• Maintenance and warranty: How often does the system need to be serviced? What warranties are offered on the modules, the inverter, and the workmanship?
• Installation: Who will perform the installation? What qualifications and references does this installer have?
• Energy sales: Are there ways to feed excess energy back into the grid? Under what conditions?
• Monitoring: How can I monitor the yield and efficiency of my system? Is there a monitoring system?
• Insurance: Do I need a special insurance policy for the PV system? Are damages caused by, for example, storm or hail covered?
• Future-proofing: How easy is it to expand or modernize the system in the future?
• Regulations and PermitsWhat official permits are required, and who takes care of them?
• Energy-efficient renovation: Would it make sense to carry out energy-efficient renovations on the building first in order to reduce energy demand?
• Module properties: How do the modules behave under different weather conditions, such as high heat or low temperatures?
• Payback period: How long will it take for the system to pay for itself?
• Financing options: What financing options are available, and which one best fits my financial situation?
• Spare parts and repairs: How readily available are spare parts? Are there local service providers who can perform repairs?
• Performance decline: How much does the performance of the panels decrease over time?
• Off-grid power supply To what extent can I achieve independence from the power grid with this system?
• Feed-in tariff: How has the feed-in tariff developed in recent years and what are the forecasts for the future?
• Extensibility: How modular is the system? Can I add more modules or an additional storage unit in the coming years?
• Environmental impact: What are the environmental impacts of the manufacturing, transport, and disposal of the modules?
• Life-cycle costs: What are the total expected costs over the entire lifecycle of the system, including maintenance, potential repairs, and replacements?
• Security: What safety precautions are required for the installation and operation of the system?
• Reviews and Recommendations: Can the provider show customer reviews or references from previous installations?

By asking these questions, property owners can ensure that they make an informed decision and get the most out of their investment in a photovoltaic system.

Conclusion – With the right preparation to the optimal PV system

If you are planning to purchase a photovoltaic system as a property owner, it is crucial to carefully examine all general conditions and select a good offer. By taking the listed aspects into account, you can find a photovoltaic system that is technically suited to your property and financially worthwhile. In this way, you contribute to the energy transition and reduce your electricity costs in the long term.