Engineering Mistakes in Solar Power Plant Design That Can Reduce Energy Generation by 20–40%

The long-term performance of a solar power plant depends not only on the quality of photovoltaic modules but also on the engineering decisions made before construction begins. Incorrect calculations of shading, module orientation, inverter sizing, cable routing or structural configuration may significantly reduce annual electricity production, increase the levelized cost of energy (LCOE), and extend the investment payback period. International studies indicate that engineering mistakes made during the design phase may reduce system performance by as much as 20–40%. Helio Solar provides engineering, equipment supply, installation and maintenance services for commercial, industrial and residential solar power plants in Kazakhstan. More information is available on the Helio Solar company profile on Mytrade.kz.

Why engineering design has the greatest impact on system performance

According to research published by the U.S. National Renewable Energy Laboratory (NREL), engineering design has a greater influence on lifetime energy production than the natural degradation of photovoltaic modules. Modern PV panels typically lose only about 0.3–0.6% of their output annually, whereas design errors can immediately reduce expected generation by more than 20% during the first year of operation.

Studies conducted by IEA PVPS and Germany's Fraunhofer ISE conclude that more than 80% of a solar power plant's long-term performance is determined before construction begins through proper engineering calculations.

Examples of completed projects are available in the Helio Solar Reels gallery.

The most common engineering mistakes affecting energy production

Inaccurate assessment of solar resources

One of the most common mistakes is relying on generalized climate data instead of site-specific solar resource analysis. Professional engineering uses databases such as NASA SSE, Meteonorm, PVGIS and Solargis to evaluate long-term solar irradiation, cloud coverage, ambient temperature and seasonal weather conditions.

According to PVsyst simulations, even a 5% error in solar resource estimation usually leads to approximately the same error in predicted annual energy production.

Ignoring shading analysis

Partial shading from nearby buildings, vegetation or technical equipment may dramatically reduce the performance of an entire PV string. NREL research demonstrates that shading only 10% of several modules may decrease string output by 30–50%, depending on the electrical configuration.

Professional projects therefore include three-dimensional shading simulations throughout the entire year.

Incorrect module tilt and orientation

There is no universal installation angle suitable for every region of Kazakhstan. Engineers calculate the optimal tilt according to geographical latitude, seasonal energy demand, snow loads, wind loads and annual solar irradiation.

• Geographical latitude
• Seasonal consumption profile
• Snow accumulation
• Wind loading
• Summer and winter production balance
• Roof structural characteristics

IEA PVPS reports indicate that a deviation of only 10–15 degrees from the optimal tilt may reduce annual generation by 2–6%, while incorrect module orientation may increase production losses up to 15%.

Current solutions and equipment are available in the Helio Solar product listings.

Inverter selection and electrical design mistakes

The inverter is the central component of every grid-connected photovoltaic system. Besides converting DC electricity into AC power, it controls Maximum Power Point Tracking (MPPT) and overall system efficiency.

Fraunhofer ISE reports that improper DC/AC sizing ratios may reduce annual energy production by approximately 8–12%.

Professional engineering includes evaluation of:

1. DC/AC sizing ratio;
2. Operating voltage ranges;
3. String current calculations;
4. Temperature coefficients;
5. Seasonal production peaks;
6. Future expansion possibilities.

Temperature modelling and ventilation design

One of the most underestimated engineering mistakes is insufficient thermal analysis. Photovoltaic modules generate electricity more efficiently at lower operating temperatures. Most crystalline silicon modules have temperature coefficients ranging between approximately –0.30% and –0.45% per degree Celsius above Standard Test Conditions (25°C).

According to Fraunhofer ISE research, module surface temperatures may reach 60–75°C during summer operation. If engineers fail to provide adequate rear-side ventilation, additional energy losses may increase by 8–15% compared to properly ventilated installations.

Professional engineering evaluates:

1. Distance between the roof and PV modules;
2. Natural airflow behind the array;
3. Roof material and surface colour;
4. Regional ambient temperatures;
5. Wind exposure conditions;
6. Optimal inverter installation locations.

Mismatch losses caused by improper module configuration

Even photovoltaic modules manufactured within the same production batch exhibit slight electrical differences. If modules are connected without proper matching or MPPT channels are incorrectly assigned, additional mismatch losses occur.

Research published by NREL and simulations performed with PVsyst indicate that mismatch losses normally range between 1% and 3%, but poorly designed systems affected by uneven string configuration or partial shading may experience losses approaching 8–10%.

Modern engineering simulations significantly reduce technical risks

Designing a modern photovoltaic power plant involves far more than selecting equipment. Engineers use specialized software including PVsyst, Helioscope, AutoCAD Electrical, Meteonorm and Solargis to simulate long-term energy production under real operating conditions.

According to the International Renewable Energy Agency (IRENA), comprehensive engineering analysis can reduce overall technical losses by approximately 10–25% compared with projects developed using simplified design approaches.

Professional engineering includes assessment of long-term climate records, electrical load profiles, snow and wind loads, degradation models, cable losses, inverter operating windows, utility grid requirements and future expansion opportunities before construction begins.

Additional renewable energy insights are available through the Mytrade.kz Reels collection.

Accurate engineering today determines financial performance for decades

Although photovoltaic equipment continues to become more efficient every year, engineering mistakes remain expensive throughout the operational lifetime of a solar power plant. Poor system layout, inaccurate electrical calculations or insufficient environmental analysis may permanently reduce energy generation, increase LCOE and delay investment payback. Thorough engineering performed before installation remains the most effective method for maximizing long-term system performance.

Helio Solar applies internationally recognized engineering methodologies when designing photovoltaic systems for commercial, industrial and residential facilities across Kazakhstan. Additional technical publications are available in the Helio Solar News section.

For a deeper understanding of project economics, read the previous article discussing payback period, LCOE, ROI and the real cost of solar electricity.

More information about renewable energy suppliers and engineering companies can be found on the Mytrade.kz marketplace.