Six key points to check for snow measures during solar power plant construction

In solar power plant construction, wind and drainage measures tend to be considered early on, while snow measures are sometimes postponed as "only relevant in heavy-snow regions." In reality, however, snow affects not only the structural safety of racking and foundations, but also risks to the surrounding area from falling snow, equipment inspectability, winter power generation maintenance, snow removal routes, and prevention of electrical equipment failures. Recent technical guides for ground-mounted solar power equipment repeatedly organize the importance of snow damage, foundation settlement, eave-end loads, and snow-removal planning, and strongly call for confirmation from the construction stage. NEDO +2 NEDO +2

What practitioners in particular should keep in mind is that snow measures are not completed by “how to remove snow after it accumulates” alone. You need to consider where and to what extent design snow loads will be assumed, how to set racking tilt angles and eave heights, where to secure falling-snow zones, how to assess foundation and ground stability, how to treat combined rain-and-snow loads for low-slope arrays, and how to translate winter inspection and snow-removal work into operational procedures. If these are not finalized at the construction stage, the range of adjustments possible on site after completion is limited. NITE site +3 Ministry of Land, Infrastructure, Transport and Tourism +3 NEDO +3

Snow measures also directly affect long-term stable operation of the plant. In a 2025 advisory, the National Institute of Technology and Evaluation (NITE) summarized that of 62 ice-and-snow incidents at photovoltaic power plants that occurred between FY2020 and FY2024, more than 90% happened in heavy-snow zones, with many cases of module and racking damage. At the same time, module and racking damage and inverter failures caused by fine snow intrusion have also occurred outside heavy-snow zones, so judgment should not be based simply on whether a site is in a heavy-snow region. It is necessary to consider both regional conditions and equipment conditions from the construction stage. NITE site

This article organizes and explains six points to check for snow measures during solar power plant construction. The content is not only for design departments but is summarized to connect to construction management, site formation planning, equipment layout, and winter maintenance operations. If you want to reduce snow-season troubles and build sites that consider post-construction maintenance, please use this as a reference. NITE site +3 Ministry of Land, Infrastructure, Transport and Tourism +3 Ministry of Land, Infrastructure, Transport and Tourism +3

Table of Contents

• Why snow measures are important in solar power plant construction

• Point 1: Decide design snow loads and local conditions by region first

• Point 2: Consider racking tilt angle, eave height, and spacing together

• Point 3: Secure clearance in front of arrays for falling snow and drifts

• Point 4: Do not underestimate foundations, ground, frost heave, and differential settlement

• Point 5: For low-slope arrays, consider post-snow rainfall as well

• Point 6: Decide snow removal, inspection, and electrical equipment placement based on operations

• Common on-site oversights in snow measures

• It’s important to connect from construction stage to maintenance

• Location-sharing ease also becomes important at snowy sites

Why snow measures are important in solar power plant construction

Snow measures are important in solar power plant construction because snow is not simply a vertical load. The Ministry of Land, Infrastructure, Transport and Tourism’s approach to snow loads is based on vertical snow depth by region to calculate snow load, and it presumes that safety is further examined with consideration of heavy-snow zones and local topographic conditions. For ground-mounted solar power equipment, applying this approach means examining not only the array surface, eave ends, foundations, and ground, but also surrounding spaces and snow-removal routes; without that breadth of view it is difficult to avoid post-construction problems. Ministry of Land, Infrastructure, Transport and Tourism +2 Ministry of Land, Infrastructure, Transport and Tourism +2

Moreover, snow not only accumulates but also slides, compacts, presses, and connects. On tilted arrays, snow can slide down and accumulate in front; when that piled snow connects to the lower edge of the array it not only obstructs exposure of the array surface but also imposes extra loads on the lower edge. The problem in snowy regions is not a design that only looks at the top of the racking, but designs that do not consider where and how the snow will accumulate after falling. If this viewpoint is weak at the construction stage, post-completion issues such as “panels remain buried in snow and are never exposed,” “lower edges bend,” or “front walkways are buried” are more likely to occur. NEDO +1

Snow is also not just a structural issue. Maintenance and inspection guides state that for ground-mounted systems, soil erosion near foundations, ground settlement, effects of freezing depth, settlement and differential settlement due to snow, scouring due to poor drainage design, collapse of embankment fill from snow and rain, and even interference from vegetation should be checked. In other words, snow measures are a subject to be considered as an integrated theme including racking strength, ground, drainage, inspection, and safe operation. If all of that is visible at construction time, site responses after snowfalls will be much more stable. JEMA Japan Electrical Manufacturers Association

Point 1: Decide design snow loads and local conditions by region first

The first thing to confirm is the assumptions for design snow loads. When it comes to snow measures, practitioners tend to judge empirically that “this region gets a lot of snow” or “this place doesn’t get that much,” but in practice that is not sufficient. The Ministry’s standard uses a unit load of at least 20 N per 1 m² for each 1 cm (0.4 in) of snow and considers vertical snow depth by region as a basis. For heavy-snow areas there are criteria such as regions where vertical snow depth is 1 m (3.3 ft) or more, and local topographic factors and nearby observational data to derive 50-year recurrence values are also taken into account. In other words, beyond regional designation, it is necessary to organize which values will be adopted for each site. Ministry of Land, Infrastructure, Transport and Tourism +1

The design and construction guidelines for ground-mounted solar power equipment also indicate that the design snow load for array surfaces should, in principle, be based on vertical snow depth at the ground, but when local topographic factors have an effect or when a 50-year recurrence value from nearby observational data is required, that information should be reflected in the design. In particular, using municipal-level figures alone is dangerous in cliff sites, ridge topography, or terrain prone to drifting. As a construction practitioner, it is important to understand how the design values were determined and to check on drawings and on site where snow biasing is likely to occur within the site. NEDO +1

It is also important not to think “it’s not a heavy-snow zone, so we can take it lightly.” Technical guides recommend that even outside heavy-snow zones vertical snow depth should be set, and that, in addition to regional observational data and government-set values, local surveys and load-guideline values should be taken into account and set appropriately. In other words, snow measures are not a special measure only for heavy-snow zones; wherever snow can fall, the design assumptions should be organized. If this is left ambiguous, subsequent racking design, eave-height settings, and foundation design will all be ambiguous. NEDO +1

Point 2: Consider racking tilt angle, eave height, and spacing together

The second point is not to decide racking tilt angle, eave height, and spacing separately. For ground-mounted solar systems, increasing tilt angle can help reduce snow loads, but it raises array height and increases the falling-snow clearance in front and spacing between rows. Conversely, prioritizing site fill efficiency with a smaller tilt angle makes snow retention more likely, and on low slopes increased load due to post-snow rainfall becomes a concern. Thus, tilt angle must be decided not only with generation output and wind loads in mind, but also considering snow movement and clearance in front. NEDO

A common real-world issue is that prioritizing generation efficiency and site filling results in tightly packed arrays that are prone to row infill in winter and lack falling-snow clearance. Technical guides state that when installing multiple arrays, spacing should be considered not only for shading effects but also for tilt angle, snow loads, foundation conditions, and maintenance space. In snowy regions, increasing tilt angle increases array height and therefore the required space both in front and between rows. Therefore, at the construction stage you must confirm not simply “higher means snow will fall off,” but also whether there is sufficient space where that snow will fall. NEDO

Eave height is even more important. Technical guides for ground-mounted arrays indicate that on tilted array surfaces snow will fall from the eave to below the eave, and when eave-under accumulation becomes large and connects with snow on the array surface, sliding snow events cease; to increase the exposure time of the array surface during winter it is desirable to secure a height equal to the ground vertical snow depth plus the eave-under accumulation due to sliding snow. Furthermore, that accumulation can be roughly twice the ground vertical snow depth. This means that if the racking lower-edge height is reduced slightly at construction, it can greatly affect winter array exposure and lower-edge loading. NEDO +1

Point 3: Secure clearance in front of arrays for falling snow and drifts

The third point is to secure front-space that assumes falling snow and drifts. Snow measures tend to focus on the snow that accumulates on top of arrays, but for ground-mounted systems the behavior of snow after it falls often has a greater impact on equipment damage and maintenance. Technical guides state that where drifting occurs on cliff sites, local topographic factors require an increase in vertical snow depth, and that on tilted array surfaces under-eave accumulation affects lower-edge loads and array exposure. In short, the area in front of arrays is not just empty space but an important zone for snow-load measures. NEDO +1

If this front space is insufficient, fallen snow tends to accumulate near fences, walkways, maintenance routes, lower arrays, drainage channels, and equipment. As a result, winter patrols become difficult, physical pressure from snow blocks is applied around equipment, and meltwater flow patterns change. In sites with strong site constraints, arrays are often packed tightly, but without considering winter falling snow this can result in places that are inaccessible, persistently snow-covered, or with buried lower edges after installation. At the construction stage, decide layouts imagining not only whether you can walk when there is no snow, but also whether you can walk after snow has fallen and accumulated. NEDO +1

The concept of front-space also relates to safety. If arrays are placed too close to surrounding roads, third-party routes, site boundaries, or other equipment, the risk of contact or burial from falling snow increases. At construction, check whether people or vehicles might enter the falling-snow area, whether equipment will be buried when snow accumulates, and whether biased accumulations such as cornices will occur. Underestimating falling snow and drifts weakens not only structural safety but also maintenance, safety, and consideration for neighbors. NEDO +1

Point 4: Do not underestimate foundations, ground, frost heave, and differential settlement

The fourth point is not to underestimate foundations, ground, frost heave, and differential settlement. When thinking of snow damage, one might first imagine module or racking deformation, but in practice foundations and ground can have more gradual yet significant effects. The 2025 guidelines for ground-mounted systems present disaster cases in which foundations tilted and racking was damaged due to snow; in heavy-snow areas, snow can cause foundation settlement or tilting, so confirming ground conditions and foundation stability under maximum snow conditions at the design stage is important. NEDO +1

Maintenance and inspection guides also indicate that ground-mounted systems should check for soil erosion near foundations, ground settlement, effects of freezing depth, settlement due to snow, differential settlement, scouring of foundations due to poor drainage design, and collapse of embankment fill due to snow and rain. This means snow measures are not just a structural-calculation issue but are deeply related to ground moisture conditions, frost lines, finishing of earthworks, and drainage design. In other words, even if snow loads are adequately considered, weak ground conditions or drainage can render the whole site unsafe. JEMA Japan Electrical Manufacturers Association

From a construction management perspective, do not be reassured simply because foundation specifications were constructed according to drawings in snowy areas. On embankments, near slopes, at sites with groundwater emergence, or where surface soils are heterogeneous, behavior can change even with the same foundation type. It is important to assume how things will move during winter frost heave and after spring thaw, and to confirm drainage and ground stability from the formation stage. Snow weight is visible, but post-thaw ground changes are easy to miss, so a margin-minded approach is needed at construction. NEDO +1

Point 5: For low-slope arrays, consider post-snow rainfall as well

The fifth point is to consider post-snow rainfall for low-slope arrays. In many sites snow loads are understood as “the weight when snow has accumulated,” but in reality rain falling on top of snow can increase loads, and long low-slope arrays require particular attention. In response to the heavy snowfall in February 2014, the Ministry strengthened regulations to consider increased loads from post-snow rainfall for certain lightweight roof structures in areas outside heavy-snow zones where vertical snow depth is 15 cm (5.9 in) or more, the length from ridge to eave is 10 m (32.8 ft) or more, and the slope is 15 degrees or less. Ministry of Land, Infrastructure, Transport and Tourism +1

The technical guide for ground-mounted systems states that because array surfaces of ground-mounted systems can be judged as lightweight, if the horizontal projected length from the top to the bottom of the array is 10 m (32.8 ft) or more and the tilt angle is 15 degrees or less, the increased load due to post-snow rainfall should be considered. In other words, sites that adopt low-slope, long arrays for site efficiency must be aware not only that snow is less likely to slide, but also that design conditions become stricter due to combined rain-and-snow loads. NEDO +1

This point matters because low slopes are often adopted for generation-area placement efficiency and wind-load considerations. The technical guide notes that in regions with large wind pressure loads, examples exist of adopting tilt angles below 20 degrees, whereas in snowy regions increasing tilt angle affects falling-snow measures and racking height. Wind, snow, site efficiency, and constructability pull in different directions. Construction practitioners should understand that while low slopes can ease some items, they increase unfavorable conditions regarding snow. NEDO +1

Point 6: Decide snow removal, inspection, and electrical equipment placement based on operations

The sixth point is to decide snow removal, inspection, and electrical equipment placement based on operational assumptions. Snow measures do not end with design; they are only complete when they include the operational framework after snow actually falls. NITE’s 2025 advisory states that to reduce ice-and-snow incident risk at photovoltaic power plants it is important to prepare before snow, and that developing a snow-removal plan in advance and discussing snow measures with security/operations personnel enables quick response to sudden snowfalls. NITE site

Snow-removal planning here is not simply “remove snow if necessary.” It is on-site operations including which routes to prioritize, where to approach equipment from, at what snow depth to make response decisions, whether to request external assistance or perform in-house work, and where to dump removed snow. If passages and spaces around equipment are not sufficient at construction, both snow removal and inspections become difficult in operation. In short, decide layouts while imagining winter work procedures. NITE site +1

Electrical equipment placement is also part of snow measures. NITE’s 2025 advisory points out that even outside heavy-snow zones inverter failures due to fine snow intrusion have occurred, and snow damage affects not only modules and racking but also equipment. Guidance on electrical equipment also advises that in snowy regions it is important to accurately convey the installation environment to equipment suppliers. At the construction stage, do not place equipment directly below falling-snow zones or in positions subject to strong snow blow-in, choose locations less prone to burial or blizzard effects, and secure winter-accessible inspection routes. NITE site +1

Maintenance and inspection guides further indicate that for ground-mounted systems one should check for foundation-area deformations, fence damage, vegetation interference, and the fastening and exterior condition of power conditioners and distribution boxes. In snowy regions these checks must be possible in winter and during thawing periods under the site’s conditions. If construction decisions are based only on whether you can walk at construction time, consider whether you can approach and confirm things when there is snow, and whether checks or removing snow will be hindered; doing so will change layout priorities. JEMA Japan Electrical Manufacturers Association

Common on-site oversights in snow measures

There are commonalities among sites where snow measures are overlooked. First, many simply rely on regional names for snow amounts. Even within the same municipality elevation and topography differ, and loading conditions change between places where drifting occurs and where it does not. Technical guides and related JIS supplements recommend checking the specific administrative authority’s regulatory content, adopting safer values, and considering local topographic factors. In short, intuitive values like “this region is about this much” are dangerous. JEMA Japan Electrical Manufacturers Association +1

Another common oversight is looking only at snow on the array and not at snow at the lower edge or in front. In practice, buried lower edges or front accumulations can prevent array exposure and add eave-end loads. If you reduce front-space for site-efficiency reasons, winter array exposure, maintenance routes, and falling-snow safety all become strained. Sites that do not assume snow falling tend to see more complaints and repairs after installation. NEDO +1

Also, separating structure and maintenance is another source of failure. Even if design loads are satisfied, sites without a snow-removal plan where equipment is hard to approach and walkways are easily buried make winter operation unstable. NITE’s advisory also stresses that to reduce accidents a pre-planned snow-removal strategy and discussions with security/operations personnel are important. If construction and maintenance are separated, the site may look fine at completion, but weaknesses surface the moment snow falls. NITE site

It’s important to connect from construction stage to maintenance

Snow measures in solar power plant construction require organizing regional design snow loads, racking tilt and eave height, falling snow and drift behavior, foundations and ground, combined rain-and-snow loads for low-slope arrays, and operation-based considerations including snow removal and inspection. Addressing just one element is not enough; if other elements are weak the whole site remains unstable. Especially for ground-mounted equipment, arrays continuously experience the sequence of snow accumulation, sliding, falling, and melting, so structure, layout, and operations must be viewed as an integrated whole. Ministry of Land, Infrastructure, Transport and Tourism +2 NEDO +2

What is important for practitioners is not to make snow measures “an item only for designers to consider.” If construction management, site formation planning, equipment layout, and handover to maintenance personnel are all considered, it is possible to get closer to a plant that is easy to operate even in snowy regions. Conversely, hasty decisions at the construction stage can leave problems such as insufficient height, insufficient front-space, insufficient snow-removal routes, and equipment burial risk after completion. Snow measures are hard to see during construction, but precisely because they are hard to see they should be finalized in advance. NEDO +2 NEDO +2

Location-sharing ease also becomes important at snowy sites

At snowy sites, it is also important that stakeholders can quickly share where snow accumulates, which equipment is prone to burial, and which routes to prioritize. On large solar plant sites, differences in location recognition during winter patrols or snow-removal decisions can delay checks and responses. In such cases, having a system that makes it easy to share equipment locations and hazardous spots on site helps manage the site during snowy seasons.

For example, using LRTK (iPhone-mounted GNSS high-accuracy positioning devices) makes it easier to identify equipment and inspection-target locations on an iPhone, which can be useful for on-site inspections during snow and for sharing priority snow-removal areas. While snow measures themselves are decided by structure and construction planning, whether people can move on site without hesitation after snow falls is a major operational difference. By including ease of location sharing in construction planning, winter site response becomes even more stable.