5 Tips for Comparing the Price and Maintenance Costs of Solar Power Plants

Table of Contents

• Compare solar power plant prices including maintenance costs

• Tip 1: Separate and organize the purchase price and annual maintenance costs

• Tip 2: Look at the relationship between generation performance and the scope of maintenance

• Tip 3: Consider equipment degradation and future repairs as part of maintenance costs

• Tip 4: Check land conditions and the burden of vegetation management

• Tip 5: Verify that inspection reports match on-site conditions

• Failures likely to occur when maintenance costs are underestimated

• Summary: When comparing prices, examine maintenance costs and on-site evidence

Compare the prices of solar power plants including maintenance costs

When considering the purchase or acquisition of a solar power plant, many practitioners first focus on the purchase price. They try to judge whether the quoted price is high or low by looking at the installed capacity, power purchase terms, generation performance, and remaining term.

However, a solar power plant is not an asset that ends with the purchase. It is a business asset operated outdoors over the long term, generating revenue while maintaining power output. Therefore, you need to compare not only the purchase price but also the ongoing maintenance costs incurred during operation.

Maintenance costs include periodic inspections, power generation monitoring, checks of electrical equipment, mowing, cleaning, management of drainage channels, repairs to fences and gates, management of surrounding trees, on-site responses to abnormalities, and preparation for equipment repairs. These vary greatly depending on the power plant’s location and the condition of its equipment. Even with the same installed capacity, the maintenance burden can differ significantly between a plant that is flat, easy to access, and has a clear equipment layout, and one that is near forested land with slopes, poor drainage, and heavy vegetation management.

For operations personnel searching "solar power plant price", what matters is not the superficial cheapness of the price but how stably it can be operated after purchase. Even a plant that looks inexpensive can increase the actual burden over the long term if maintenance costs are heavy and equipment degradation, vegetation management, and drainage management require considerable effort. Conversely, a plant that appears expensive may be worth considering as an easy-to-manage project if the maintenance scope is clear, generation performance is stable, and the condition of the equipment and land is good.

When comparing maintenance costs, be careful not to assume that lower costs are simply a positive indicator. Even power plants with low past maintenance costs may have merely failed to carry out necessary inspections, grass cutting, drainage management, and equipment repairs. For such plants, switching to proper management after purchase may increase maintenance costs more than expected. Conversely, if a certain level of maintenance cost is incurred but, as a result, power generation is stable and equipment is kept in good condition, those costs can be regarded as necessary management expenses.

In this article, we outline five tips for practitioners to compare the purchase price and maintenance costs of solar power plants. Rather than specific amounts, we focus on which items to check before purchasing and how to incorporate them into price assessments.

Tip 1: Separate the purchase price and annual maintenance costs

The first tip is to clearly separate and organize the purchase price and the annual maintenance costs. In project documents, purchase conditions and expected revenues tend to stand out, and maintenance costs are sometimes shown only in a simplified way for certain items. However, the actual burden of a solar power plant only becomes apparent when the purchase price and the ongoing operational costs are combined.

The purchase price may include power generation equipment, the land or land-use rights, terms for electricity sales, past operational performance, and, in some cases, the transfer of management contracts and related documentation. However, what is included varies from case to case. Unless you confirm whether the land is included, whether a land lease agreement is being assumed, whether existing maintenance and management contracts will be continued, or whether there are outstanding repairs to be addressed, you cannot correctly assess the meaning of the price.

On the other hand, maintenance costs continue to be incurred after purchase. Items that occur annually include inspections, monitoring, insurance, land-related management, administrative tasks, mowing, and cleaning. Those that tend to occur at regular intervals include detailed inspections, equipment upgrades, repairs to drainage facilities, repairs to fences and gates, and reviews of surveillance equipment and communication environments. In addition, if typhoons, heavy rain, fallen trees, equipment outages, or similar events occur, emergency responses and recovery checks may also be required.

In price comparisons, projects with a lower purchase price tend to appear more advantageous. However, when you break down maintenance costs separately, the actual picture can change. Even if the purchase price is low, conditions such as intensive vegetation management, advanced equipment deterioration, frequent drainage cleaning, difficulty accessing the site, or insufficient inspection reporting will increase post-purchase maintenance costs. Conversely, even if the purchase price is somewhat higher, if maintenance arrangements are well established, on-site management is easy, and generation performance is stable, it may be easier to consider the project from a long-term perspective.

In practice, it can also be useful to separate maintenance costs into normal-period costs and abnormal-period costs. Normal-period costs are expenses for maintaining power generation, such as inspections, mowing, monitoring, and cleaning. Abnormal-period costs are expenses for responding to equipment shutdowns, post-disaster inspections, cable damage, poor drainage, fence damage, and the like. Comparing only normal-period costs may lead to underestimating power plants with higher risk.

By separating and organizing the purchase price and maintenance costs, you can more easily spot the hidden burdens behind low prices and the management-related reassurance contained in projects that seem expensive. When comparing solar power plants, this breakdown is the starting point.

Tip 2: Examine the relationship between power generation performance and maintenance activities

The next tip is to look at the relationship between power generation records and maintenance activities. The revenue of a solar power plant depends on its power generation, and that generation is maintained not only by solar irradiance conditions but also by routine maintenance. If past power generation records have been stable, it is important to check what kinds of inspections, grass cutting, cleaning, and equipment checks were carried out behind that.

When evaluating power generation performance, the annual total alone is insufficient. Even if the annual totals don't show major problems, a monthly breakdown may reveal drops in generation during specific periods. Possible causes include weeds growing and casting shadows on panels in summer, longer shadows from surrounding trees or terrain in winter, impacts from fallen leaves or accumulated snow, and equipment outages or maintenance shutdowns. Such variations in generation only make sense when cross-checked against maintenance records.

Also review multi-year trends. Even if a single year’s power generation is high, that year may have simply enjoyed favorable weather. If generation is gradually declining over several years, causes may include panel soiling, vegetation growth, malfunctions in power conversion equipment, deterioration of cables or connection hardware, insufficient cleaning, or poor drainage. If there is a drop in generation performance, check the inspection reports and maintenance records for that period.

When reviewing maintenance details, we look not only at whether work was performed, but also at what was inspected, what issues were identified, and how they were remedied. If the inspection report notes panel soiling, vegetation overgrowth, cable damage, mounting-structure corrosion, or clogged drainage channels, we verify whether those issues were subsequently addressed. If the same issues are repeatedly noted, it may indicate that the maintenance frequency or management methods are not appropriate for local conditions.

If a power plant with low maintenance costs is experiencing a decline in generation performance, it is possible that cost-cutting has led to inadequate management. Conversely, if maintenance costs are at a certain level and generation performance is stable, those costs can be seen as contributing to maintaining generation output. In other words, maintenance costs should not be judged solely by being low, but by whether they are appropriate for maintaining generation performance.

When comparing price and maintenance costs, it is important not only to view maintenance expenses as expenditures to be deducted from electricity sales revenue, but also as an investment to protect power generation. Cutting maintenance may temporarily reduce spending, but if it delays detection of reduced output or equipment failure, it can result in significant losses. By linking generation performance with maintenance activities, you can make a more realistic judgment about the reasonableness of the price.

Tip 3: Include equipment deterioration and future repairs in maintenance costs

When comparing maintenance costs for solar power plants, you need to consider not only routine inspections and grass cutting but also equipment degradation and future repairs. Because plants operate outdoors for long periods, solar panels, power conversion equipment, mounting structures, foundations, cables, connection equipment, monitoring devices, fences, and drainage systems gradually deteriorate. Even if current maintenance costs look small, if repairs are needed in the near future the actual burden can become significant.

For solar panels, check for dirt, cracks, discoloration, loose mounting components, and the effects of shading. Dirt and fallen leaves can sometimes be remedied by cleaning, but if there are cracks, discoloration, or problems with mounting components, repairs or replacement should be considered.

For power conversion equipment, check the installation age, outage history, repair history, and replacement history. If outages are frequent or recurring restorations of unknown cause are occurring, they should be considered a future replacement risk.

Cables and connection equipment are also important. Damage to cable sheathing, damage to protective conduits, deterioration of connection points, contact with vegetation, and damage caused by animals affect safety and the risk of power generation stoppages. These issues are hard to see from photos alone, so it is necessary to check areas hidden by vegetation and beneath mounting racks on site. When comparing maintenance costs, if deterioration of such hard-to-see equipment is not included, unexpected repairs may occur after purchase.

For the racking and foundations, check for corrosion, tilt, loosening of fastenings, and scour or settlement around the foundations. These may not immediately appear in power generation performance, but they affect safety during strong winds or heavy rain and future repair costs. On land with poor drainage, deterioration around the foundations may progress more easily. If an inspection report points them out, confirm whether they have been remedied afterward.

Future repairs are not costs that occur evenly every year. They can occur in concentrated periods. Therefore, when comparing maintenance costs, it is important to anticipate not only the annual upkeep costs but also the repairs likely to arise during the remaining operational period. Based on inspection reports, repair histories, equipment age, and changes in power generation performance, we identify which pieces of equipment are likely to become future burdens.

For lower-priced listings, the low price may reflect the need for future repairs. For higher-priced listings, the price may be justified by the fact that repairs have already been carried out or that equipment is in good condition. When comparing maintenance costs, it is essential to take into account not only current expenses but also the risk of future repairs.

Tip 4: Check the land conditions and the burden of vegetation maintenance

Maintenance costs for solar power plants vary greatly depending on land conditions. Even when the power generation equipment is in similar condition, the maintenance burden will differ depending on whether the land is flat and easy to manage, has slopes, has poor drainage, is close to forests or farmland, or has good road access. When comparing price and maintenance costs, it is important to evaluate the land not merely as an installation site but as the site where operation and maintenance take place.

Vegetation management in particular has a major impact on maintenance costs. On land where weeds grow easily, the frequency of mowing and weeding increases. If vegetation casts shadows on the lower parts of panels, power generation may decrease. If vegetation grows densely around cables and connection equipment, it becomes harder to detect deterioration or damage during inspections. If vegetation around fences is left untrimmed, signs of damage or animal intrusion can be overlooked.

We also check the terrain of the site. Flat land is often easier to work on, but areas where moisture tends to remain or where drainage is poor allow grasses and plants to grow more easily. At power plants with sloped ground or embankments, the safety and efficiency of mowing work decrease. At power plants where maintenance paths are not well established, not only mowing but also inspections and repairs require more effort.

Access roads and entry routes also affect maintenance costs. Check whether maintenance vehicles can easily enter the power plant, whether gates and access paths are easy to use, whether they get muddy in wet weather, and whether there is space for vehicles to turn around. At plants in remote locations with poor access, routine inspection and emergency response costs can be significantly higher. Difficulty accessing the site affects not only maintenance costs but also the duration of power generation downtime during incidents.

Drainage conditions should not be overlooked. On land where drainage channels are prone to clogging, sediment easily flows in, or water tends to accumulate, inspections, cleaning, and repairs are necessary after heavy rain. If poor drainage persists, it can have adverse effects on foundations, cables, and maintenance access routes. Drainage management is an important factor related to both equipment maintenance and vegetation management.

With low-priced properties, the burden of land conditions and vegetation management may not be sufficiently accounted for. Even with higher-priced properties, if the land is easy to manage and the risks from vegetation and drainage are low, there is value in having predictable long-term maintenance costs. When comparing maintenance costs, it is important to always verify land conditions on site.

Tip 5: Confirm that the inspection report matches the on-site conditions

The final tip is to verify that the inspection report matches the on-site conditions. Inspection reports are an important resource when determining maintenance costs for a solar power plant. However, you should not be reassured by the mere existence of a report. You need to confirm whether the contents of the report accurately reflect the actual on-site situation, whether the identified issues have been remedied, and whether the locations shown in the photos can be identified.

In an inspection report, we look at how thoroughly the condition of panels, power conversion equipment, cables, connection equipment, mounting structures, foundations, monitoring devices, fences, drainage channels, and vegetation has been checked. If the findings are specific, it becomes easier to estimate maintenance costs and future repairs. On the other hand, if the report is formulaic, contains few photos, and lacks a clear history of improvements, it becomes difficult to assess the actual state of management.

During on-site inspections, we verify the contents described in the report against the actual conditions. We check whether areas the report judged to be problem-free have overgrown vegetation, clogged drainage channels, damaged fences, or deteriorated cables. Conversely, we also confirm whether locations that the report flagged have been remedied on site. Only when the documentation and the on-site conditions match does the maintenance cost estimate gain credibility.

Location information for photos is also important. Even if an inspection report includes photos, if it is not clear where they were taken they become difficult to use for repair estimates or management instructions. Damaged areas, the extent of vegetation overgrowth, locations of poor drainage, inspection points near boundaries, and abnormalities around electrical equipment should ideally be recorded together with their locations. Photos whose locations are unknown alone leave room for uncertainty in internal briefings and in handovers after purchase.

In power plants where the inspection report does not match the on-site conditions, expected maintenance costs may be off. In low-priced projects, the low price may stem from insufficient reports or poor on-site conditions. In high-priced projects, the price may reflect the value of detailed reports and thorough on-site management.

When comparing maintenance costs, you should verify not only the costs shown in the documents but also the reliability of those documents. If the inspection report matches the on-site conditions, it will be easier to develop a post-purchase management plan. Conversely, if they do not match, additional investigations and a review of management costs will be necessary.

Failures That Commonly Occur When Maintenance Costs Are Underestimated

Underestimating maintenance costs can greatly distort the valuation of a solar power plant. Even if the purchase price looks low, required inspections, grass cutting, cleaning, repairs, and emergency responses after acquisition can increase, making the actual burden heavier. Even if the surface-level revenue and returns appear favorable, subtracting maintenance costs can mean you don’t receive the expected net proceeds.

A common mistake is to regard low past maintenance costs as a positive sign. In reality, the low costs may simply reflect that necessary maintenance was not adequately performed. If inspections were insufficient and equipment deterioration was overlooked, grass cutting was delayed and power generation declined, or clogged drainage channels were left unaddressed, switching to proper management after purchase will increase costs.

You may also overlook a decline in power generation performance. If the output has fallen due to insufficient maintenance, it may be possible to improve it after purchase, but that will require additional management and repair costs. If you judge solely by price without checking the reasons for the low output, your revenue outlook will be overly optimistic.

Underestimating equipment degradation is also a major risk. Even if current power generation appears to be fine, replacement of power conversion equipment, cable repairs, repairs to racking and foundations, and updates to monitoring systems may be required. These can become a substantial burden separate from routine maintenance costs. If future repairs are not anticipated, unexpected expenses will arise after purchase.

Overlooking land conditions can also lead to failure. Conditions such as rapid vegetation growth, poor drainage, weak road access, maintenance access paths that are difficult to use, and ambiguous boundaries increase maintenance costs. If the reason the price is low is due to the land conditions, it may become a continuing burden after purchase.

To avoid underestimating maintenance costs, it is important to not only review the documents but also inspect the site and cross-check inspection reports, repair histories, and power generation records. When determining the price of a solar power plant, you must account for not only the purchase price but also the maintenance costs required over the entire operational period.

Summary: When comparing prices, consider maintenance costs and on-site evidence

To compare the price of a solar power plant and its maintenance costs, it is important to separate the purchase price and the annual maintenance costs, examine the relationship between generation performance and maintenance activities, consider equipment degradation and future repairs, check land conditions and the burden of vegetation management, and confirm that inspection reports match on-site conditions. Maintenance costs are not merely expenditures but management costs to maintain power output and asset value.

There may be reasons why a low-priced power plant is inexpensive. Insufficient maintenance, equipment degradation, the burden of vegetation management, poor drainage, difficult site access, and inadequate inspection reports may be behind it. Even for high-priced power plants, if generation performance is stable, maintenance practices are clear, and the equipment and land are in good condition, they can be easier to consider as long-term investments.

What matters for operational staff is to organize maintenance costs as evidence that can be used for internal explanations. They need to connect power generation records, inspection reports, repair history, grass-cutting history, cleaning history, land contracts, and on-site verification results so they can explain why those maintenance costs are necessary and how they affect the price.

During on-site surveys, it is effective to record inspection points that affect maintenance costs together with precise location information. If panels, power conversion equipment, cable routes, drainage channels, areas of vegetation overgrowth, fence damage, locations near boundaries, and candidate repair sites can be recorded with location information, they can be readily used for instructions to the management company, repair estimates, and internal approval procedures.

Using LRTK (an iPhone-mounted GNSS high-precision positioning device) is also effective when you want to organize solar power plant maintenance costs together with on-site evidence. If you can record the locations of equipment within the plant, drainage channels, the extent of vegetation, causes of shading, candidate repair locations, and points of caution near boundaries along with high-precision positional information, you can reconcile discrepancies between drawings and the field and make it easier to share the factors that affect maintenance costs among stakeholders. When judging the price of a solar power plant, it is important to build up not only desk-based figures but also maintenance costs and on-site verifiable evidence.