Benefits of Slope and Shading Analysis Learned at the PV EXPO: Supporting Investment Decisions and Maximizing Power Generation Efficiency

In recent years, at trade shows like the PV EXPO, the solar power industry has focused attention on new technologies such as "slope analysis" and "shading analysis." While solar power is expected to be a mainstay energy source for a decarbonized society, the environment surrounding the industry has changed substantially. With the reduction of the feed-in tariff (FIT), falling purchase prices, and rising demand for rooftop and constrained-space installations, there is a greater need than before for precise estimates of power generation and for maximizing efficiency. For this reason, technologies that analyze slope and shading in detail have come to play an important role in supporting investment decisions and optimizing actual power generation.

This article explains the significance of slope and shading analysis, which are topics at the PV EXPO, with construction companies and small-to-medium rooftop installers in mind. We will carefully unpack why these analyses are useful for investment decisions and how they can maximize generation efficiency, along with the latest industry trends and background. We will also introduce how to use the latest technologies—such as the recently introduced smart construction support system LRTK—for slope and shading measurement, point-cloud scanning, and AR navigation-guided panel placement, and we will touch on the benefits of applying these tools in installation proposals.

Industry background: FIT reduction and rising demand for rooftop installations

First, let's organize the industry background. In Japan, the FIT (feed-in tariff) started in 2012, and because it initially guaranteed purchase at a high rate in the 40-yen-per-1kWh range for 20 years, investment in solar power exploded. However, subsequent annual revisions to the purchase price gradually lowered rates, and by the mid-2020s residential rates had fallen to around 15 yen per 1kWh and business rates to about 10 yen per 1kWh【EV DAYS commentary】(https://evdays.tepco.co.jp/entry/2022/01/06/000027). The FIT period has also been shortened; for small-scale installations the guarantee is limited to 10 years, so relying on feed-in income for stable revenue is no longer as feasible as it once was. Therefore, to secure the profitability of solar power businesses, reducing generation costs, utilizing self-consumption, and operating to maximize actual power generation have become important.

Recently, while development of large-scale mega-solar sites has stalled due to local opposition and scarcity of suitable land, utilizing unused rooftop space on buildings has been actively promoted. The government has also shown increased urgency and announced a policy to require formulation of rooftop solar installation targets for factories and stores above a certain scale from fiscal 2026【SOLAR JOURNAL column】(https://solarjournal.jp/information/61844/). This policy aims to expand renewable energy deployment by placing panels on previously underused rooftops. In Germany, about 70% of solar capacity is rooftop installations on homes and industrial facilities, whereas Japan’s figure remains around 40%, indicating significant rooftop potential in Japan【SOLAR JOURNAL column】(https://solarjournal.jp/information/61844/). Driven by these trends, demand for installing solar panels on house and small-building roofs, narrow idle lots, and over parking lots is likely to increase.

However, to secure maximum generation from limited roof area, more precise design and simulation than ever before are required. Unlike large ground-mounted systems, rooftop installations are relatively more affected by differences in slope angle and shadows from surrounding obstacles. That is where slope analysis and shading analysis become important. From the next sections, we will look at what these analyses mean concretely and how they help.

What is slope analysis: Generation potential determined by roof angle and orientation

Slope analysis evaluates whether a mounting surface’s tilt (slope) and orientation (azimuth) are suitable for power generation. Solar panels generate electricity most efficiently when they receive sunlight at an angle close to perpendicular to the solar irradiance. Therefore, the tilt angle of the mounting surface and its north–south orientation are key factors that determine generation potential.

Generally, in the Honshu area of Japan, a tilt angle around 30 degrees tends to maximize annual generation, and panels ideally face due south. However, on actual rooftops the roof shape fixes the tilt and orientation, so conditions are not always ideal. For example, on gently sloped flat roofs (low-slope flat roofs), panels are close to 0 degrees (horizontal), and the shallower elevation reduces annual generation somewhat. On the other hand, on steep single-sloped roofs the angle may exceed 30 degrees, which can be advantageous in winter but sometimes reduces generation in summer. If a roof faces east–west, panels are installed on east and west faces rather than due south, producing power in the morning and evening but with lower peak output than south-facing installations. North-facing roofs receive significantly less insolation in Japan and are generally deemed unsuitable for solar installations.

Slope analysis accurately measures and calculates such roof pitch and azimuth to evaluate how suitable a roof is for power generation. Specifically, practitioners measure the roof angle with a protractor or inclinometer, or calculate pitch from architectural drawings. Azimuth is checked with a compass or positioning tools to determine the deviation from true south. Using solar-angle theory and historical weather data, they then calculate the expected annual energy yield under those conditions.

Whether the tilt angle is appropriate affects not only generation efficiency but also installation methods and construction costs. For instance, on flat roofs adding racks to tilt panels can increase generation but raises cost and structural load. Conversely, on very steep roofs panels are more exposed to wind, so the strength of mounting hardware and installation methods require attention. By conducting slope analysis in advance and considering the optimal installation plan for that roof (for example, allocation to east–west faces, rack-angle adjustments, and fastening methods), it is possible to design with a balance of efficiency and safety.

In short, slope analysis is the process of determining how much generation a roof can produce and identifying design challenges and potential solutions. Proper analysis can prevent post-installation complaints or malfunctions such as “it generates less than expected” or “the angle makes maintenance difficult.”

What is shading analysis: Interpreting shadow impacts to minimize generation loss

Shading analysis identifies factors that cast shadows on panels and quantifies their impact. Solar panels suffer large output drops even from partial shading. In extreme cases, a small shadow over some cells can limit the current in a series string and cause generation loss or hot spots. On rooftops, surrounding buildings, chimneys, trees, utility poles, and other objects may cast shadows, and shadow positions change with time of day and season. Shading analysis is essential for identifying shadow sources and the area and timing of shadowing and for evaluating the impact on annual energy yield.

There are two main approaches to shading analysis: on-site inspection and simulation. On-site inspection involves observing the surroundings from planned panel locations and estimating shadows by comparing with the sun’s path. A traditional technique is to draw surrounding obstructions on a sun-path chart (all-sky graph) used for insolation calculations to determine annual sunshine hours. Dedicated shadow-measuring devices or fisheye-lens all-sky cameras are also used. Based on such surveys, you can determine things like “at noon on the winter solstice the neighbor’s shadow partially covers this area” or “after 3 pm the western adjacent building will shade this area.”

In recent years, 3D simulations on computers have become common. By modeling the building and surroundings in 3D and reproducing the sun’s movement in software, you can simulate time-of-day shadows. Although used in architectural design, these techniques have been adapted for solar power. This allows quantitative calculation of shading loss rates on annual generation. For example, a roof with a projected annual yield of 5,000 kWh might suffer a 5% shading loss, yielding an actual 4,750 kWh.

The value of shading analysis lies in understanding shadows in advance and taking countermeasures. If analysis shows significant shading impact, several responses are possible, such as:

• Layout optimization: Avoid placing panels in areas prone to shading. If some areas are inevitably shaded, reduce panel count there and concentrate panels in reliably sunlit areas.

• Equipment selection: Use systems resilient to partial shading, such as microinverters or power optimizers. With traditional series-connected systems and a centralized inverter, shading on a portion can reduce the entire string, whereas per-panel control localizes losses to shaded panels.

• Environmental adjustments: Reduce shading sources where feasible. For example, trim or remove on-site trees, negotiate with neighboring structures for light-blocking countermeasures, or relocate rooftop antennas or chimneys if possible to remove shadow sources.

• Time-of-day generation planning: If shading is unavoidable in the morning or evening, design to prioritize midday peak generation—e.g., use batteries to store midday surplus and discharge in the evening—to indirectly mitigate shading effects.

By optimizing installation plans and equipment configuration based on shading analysis, shading losses can be minimized. Even on narrow, challenging sites, careful analysis of shadow movement can prevent catastrophic failures such as “after installation it barely generated in the afternoons.”

The role of analysis in investment decisions

Slope and shading analyses quantify potential generation and risk factors, making them extremely useful tools for solar investment decisions.

When introducing rooftop solar, contractors and installers present expected generation and financial plans to owners (clients). How many years to recoup investment, how much electricity bill savings or feed-in revenue can be expected—these are critical decision factors for customers. You cannot state projections without evidence, and if the customer later says “this isn’t what you told us,” it becomes a trust issue. Detailed simulations informed by slope and shading analysis are powerful here.

For example, consider a case of installing 10 kW of solar on a store roof. A simple estimate might say “about 10,000 kWh per year,” but due to roof orientation, angle, and surrounding shading it might actually be 20% less—8,000 kWh. With slope and shading analysis you can present grounded figures like “about 8,000 kWh per year under these conditions, totaling ○○ kWh over 10 years.” Providing simulation reports with monthly generation graphs and shading-impact breakdowns (what percentage loss occurs in which months) gives customers strong reassurance. Presenting clear risk-and-return scenarios supports their investment decisions.

Detailed analysis data also increases credibility when seeking financing from banks or leasing companies. Especially for commercial (high-voltage) projects, lenders often require evidence for generation estimates; predictions accounting for slope and shading help pass project reviews. Conversely, optimistic estimates made without analysis can lead to underperformance and cashflow problems. Accurate pre-project analysis increases the stability of business plans and enhances the installer’s credibility.

In short, slope and shading analysis allow you to coherently present scenarios such as “installing here will generate this much and yield this revenue (or bill savings).” This reassures customers and strengthens the persuasive power of investment proposals. For installers, data-driven proposals reduce the risk of taking on unprofitable projects based on vague intuition.

Using analysis to maximize generation efficiency

Beyond the investment stage, results from slope and shading analyses directly contribute to maximizing actual generation during construction and operation. Feeding analytical insights into design and construction enables practical measures to literally maximize energy output.

Based on slope analysis, if a roof angle deviates from the ideal, construction methods can compensate. For example, on flat roofs consider using specialized racks to tilt panels to an appropriate angle. Since increasing rack angle too much can cause panel interference or increased wind load, reconcile the analytically determined “optimal angle” with actual construction constraints to choose a safe and efficient compromise angle. On very steep roofs panels are usually mounted flush with the roof, but if analysis finds a large azimuth deviation you might prioritize installation on the south-facing roof only. For multi-faceted roofs, analysis informs strategic choices such as whether to include east–west faces to boost total output or to avoid a heavily shaded west face.

Shading analysis produces even more practical insights. Knowing the times and areas that receive shadows allows adjustments at the layout stage, such as “skip this array row” or “leave a small gap here.” For example, if a lightning rod or vent in one roof corner casts a shadow in the afternoon, thin out panel layout only around that area and densely fill the rest. Even if shading loss is only a few percent annually, concentrating that loss on specific panels localizes damage. Optimizing layout according to the shading pattern discovered in analysis maximizes total generation while minimizing shading impact.

Analysis also informs equipment choices. If shading analysis shows the west half will be shaded after 4 pm in winter, separate that half into independent strings. Then only the shaded string’s output drops while other strings remain unaffected. Preemptively designing with microinverters or similar technologies provides further mitigation. In short, use analysis results to configure a system with high shade tolerance.

By applying slope and shading analysis, you can achieve meticulous, waste-free design from the construction stage and thereby maximize generation efficiency. To extract every possible kWh from limited roof area, fully incorporate analytic insights into your design.

Advanced technologies supporting slope and shading analysis (point-cloud scanning and AR)

High-level slope and shading analyses require detailed on-site measurement data. Traditionally, collecting such data was time-consuming. For example, measuring roof slope required ladders and protractors or laser levels, and investigating surrounding shadows meant repeated on-site observations at different times. For small and mid-sized installers, acquiring specialized surveying personnel and expensive equipment was a high hurdle, and in some site conditions accurate data could not be obtained.

Recently, however, advanced technology tools have changed this situation. A representative example is the simple surveying system that works with a smartphone, “LRTK.” LRTK combines a high-precision GNSS (RTK) receiver with a smartphone’s built-in LiDAR (light detection and ranging sensor) to enable anyone to easily perform 3D surveying with centimeter accuracy (cm level accuracy (half-inch accuracy)). By walking around a roof and building surroundings while holding a smartphone, you can capture high-precision point-cloud data (a collection of innumerable 3D coordinate points) as if recording a video.

Point-cloud data are digital measured models obtained by scanning the terrain and structures in 3D. For example, if you acquire a house roof as a point cloud, you obtain a realistic 3D dataset representing roof dimensions, slopes, heights, rooftop obstructions, and surrounding buildings and trees at true scale. LRTK’s RTK-GNSS assigns absolute coordinates (latitude, longitude, elevation) to all points, so aligning point clouds with each other and with design drawings is easy. Where high-quality 3D data previously required specialized surveying equipment or drone photogrammetry, with LRTK one person can complete the job in a matter of tens of minutes.

This point-cloud data is extremely useful for slope and shading analysis. First, it enables automatic calculation of slope angles. Fitting a plane to roof-surface points yields tilt and azimuth angles instantaneously in software. This is more precise than manual tape-and-calculation methods and works accurately even for complex single-slope roofs or curved roofs. Roof area and dimensions can also be measured automatically from point clouds, allowing data-driven consideration of “how many panels fit” and “how to lay them out.”

Point-cloud data are particularly powerful for shading analysis. Instead of inferring the environment from drawings or photos, point clouds retain the surroundings as a 3D model. You can measure the height and distance of neighboring houses or the overhang of nearby tree branches directly on the point cloud. By importing these into dedicated software for solar radiation simulation (shadow calculations using point-cloud data), you can perform shading analysis while reproducing the actual site in the computer. Even without full simulation, inspecting the point cloud provides intuitive understanding—“the winter-morning sun will be blocked by this building” or “this antenna’s shadow equals how many panels.” In short, digitizing the site allows detailed analysis back at the office.

LRTK also offers many convenient features for using acquired point clouds and design data. For example, you can view and share point clouds in the cloud, measure distances and areas, and overlay CAD drawings for comparison. Notably, it includes AR (augmented reality) features. When you view the site through your smartphone, you can accurately overlay a 3D model in-place without displacement. This is possible because RTK gives precise position and orientation. If you prepare a 3D model of the panel layout, you can view it on-site as if the layout were painted onto the real roof. AR-based panel placement simulation and marking make client explanations and installation verification easier.

Competitive advantages for contractors adopting LRTK

By adopting advanced tools like LRTK, contractors gain significant advantages across surveying, design, and construction. The main benefits include:

• Improved on-site survey efficiency: Roof dimension and angle measurements that once took hours can be completed quickly with LRTK. One person can scan roof shapes and surrounding environments, minimizing labor and scaffolding needs and enabling rapid acquisition of detailed data even on busy sites.

• Enhanced proposal accuracy: Slope and shading analysis results based on point-cloud data can be directly reflected in proposals. Presenting precise generation simulations and visualized shading evidence allows persuasive customer proposals. Showing grounded figures differentiates you from competitors and builds trust.

• Optimized construction planning: Simulating panel layouts and rack installation on the acquired 3D model minimizes design errors and rework. Checking the finished appearance on-site using AR helps discover and correct issues like “interference with piping” before construction.

• Improved construction quality and safety: LRTK’s coordinate/AR navigation guides the exact installation and mounting locations on site. Even without surveying expertise, following smartphone instructions lets workers mark locations with an error of less than several centimeters (cm level accuracy (half-inch accuracy)), preventing crooked panel rows or spacing errors. This standardizes construction quality and reduces the risk of rework or repairs.

• Strengthened customer service: Point-clouds and AR are also effective customer-explanation tools. Showing an AR-rendered finished image helps clients intuitively grasp the post-installation appearance and feel reassured. Storing point-cloud data after construction allows comparison with the original state during after-sales maintenance. Providing such digital data enhances customer satisfaction.

Thus, adopting LRTK creates a virtuous cycle of shorter surveys → stronger proposals → improved construction efficiency and quality → higher customer satisfaction. As long as competitors still rely on manual methods, early adopters of digital technology can secure a competitive edge.

Conclusion: Make slope and shading analysis your ally with the latest technologies

Because of FIT reductions and changing market conditions, the solar power industry now demands more meticulous planning and technical capability than ever. Especially as rooftop and constrained-space installations increase, slope and shading analysis are indispensable steps to support investment decisions and maximize actual generation. As highlighted at the PV EXPO, the industry is beginning to recognize the importance of digital analysis and simulation.

What matters is putting analysis into practice. Using advanced tools like LRTK makes previously difficult precision field analyses accessible to anyone on site. Visualizing tilt angles and shading impacts with data and feeding those insights back into design and construction lets you maximize the power you can extract from limited roofs. Building advanced analytic capabilities also dramatically improves your proposal strength and reliability as a contractor.

Moving toward solar power that generates sufficient benefit even without relying on feed-in tariffs—the key lies in meticulous planning using slope and shading analysis and in adopting advanced technologies. We encourage you to proactively use the latest analysis tools and digital systems like LRTK to differentiate your services and propose the best solar plans to your customers. By anticipating industry trends and achieving both high generation efficiency and customer satisfaction, you can establish robust competitive power in the future solar business.