Are prices of used solar power plants reasonable? 5 things to check before buying

Table of Contents

• What determines the price of a used solar power plant?

• Check 1: Confirm power sales conditions and remaining term

• Check 2: Confirm generation performance and degradation factors

• Check 3: Confirm equipment condition and replacement risk

• Check 4: Confirm land, rights, and contractual matters

• Check 5: Confirm maintenance costs and future risks

• Don’t judge by price alone; proceed with on-site inspection and data organization

What determines the price of a used solar power plant?

When considering the purchase of a used solar power plant, the first thing you should check is whether the offered price is commensurate with its future profitability and risk. Unlike new projects, used projects already have an operational track record. On the other hand, feed-in conditions, land-use status, the ageing condition of equipment, maintenance history, and past responses to defects vary from case to case. For that reason, it is not appropriate to judge a plant as "cheap" or "expensive" based only on capacity or apparent yield.

The price of a used solar power plant is not determined solely by the value of the generation equipment itself. Prospects for future electricity sales revenue, the remaining period of feed-in, the stability of generation performance, the extent of equipment degradation, land use conditions, ease of management, future burdens related to repairs or decommissioning, and legal and contractual checks all have a combined effect. In other words, the quoted price is only the entry point, and it is important to clarify what conditions and risks you are taking on at that price.

Especially for second‑hand projects, past operating conditions affect future maintenance burdens. Even for power plants of the same size, the actions required after purchase differ between facilities where inspection, mowing, cleaning, and repair records are well organized and those that have received only minimal management. If weed control is insufficient and shading occurs, if panel soiling or damage has been left unaddressed, or if inspection records for electrical equipment are missing, additional surveys or remedial work may be required after purchase.

Also, when assessing whether a price is reasonable, it is important not to reach a conclusion based solely on the materials provided by the seller. Cross-check generation records, electricity sales statements, inspection records, contracts, drawings, on-site photos, equipment ledgers, land-related documents, and so on, and verify that there are no inconsistencies among the materials. Even if the documents appear to show no major problems, a site visit may reveal issues such as growth of surrounding trees, poor drainage, deterioration of fences, environmental degradation around the power conditioner, or difficulty of using the access road.

A used solar power plant, if conditions are right, can potentially be taken over and put into operation sooner than a newly built one. On the other hand, because it has already been in operation for some time, you will also inherit risks that are harder to see. Before looking at the price, it is important to first consider: "Is it in a condition to continue generating electricity reliably in the future?", "Are there contracts and management systems in place to support revenue?", and "Is it unlikely that unexpected burdens will arise after purchase?".

This article organizes the key points that practitioners should check before judging whether the price of a used solar power plant is reasonable. Rather than presenting specific amounts or market prices, it focuses on how to interpret the conditions behind the price. By identifying the items to confirm in the preliminary stage of a purchase decision, you will be less likely to be swayed by apparent cheapness and better able to make decisions based on long-term operation.

Check 1: Verify the feed-in tariff conditions and remaining contract period

When evaluating the price of a used solar power plant, the first thing you should check is the electricity sales terms. The profitability of a solar power plant depends on the conditions under which the electricity it generates can be sold. Therefore, in addition to installed capacity and location, you need to confirm under which system or contract the electricity is being sold, how much time remains in the sales period, and whether the buyer can assume those terms.

When reviewing power sale conditions, it's important not to focus solely on the power purchase price. Organize the contract start date, operation start date, remaining duration of the power sale period, certified equipment ID, name of the power producer, contract with the utility company, procedures for changing the business plan, and documents required for succession or name changes. For second-hand projects, since buyers often inherit the conditions under which the seller has been operating, it is important to confirm in advance that there will be no issues with the transfer.

The remaining term is a major factor when assessing the reasonableness of a price. If the period during which you can earn revenue from electricity sales is long, it becomes easier to project future income. Conversely, for projects with a short remaining term, the time available to recover the investment after purchase is limited. A short remaining term is not necessarily immediately disadvantageous, but in such cases you should examine the condition of the equipment, operating costs, and exit policies — including removal and reuse — more carefully.

Procedures for changing the registered owner or amending the business plan also need to be checked. For power plants certified under FIT or FIP, changes in the content may require applications or notifications to the national government and procedures with the power company. Depending on the scale of the equipment, the installation location, and the nature of the changes, there may be cases where it is necessary to confirm whether briefings or prior notification measures are required. Even if the seller explains that the procedures can be "taken over," it is important to confirm in documents the required paperwork, the status of applications, the status of obtained consents, and the expected completion date.

In addition to the electricity sales contract, we also check conditions related to grid connection and output control. Connection agreements, supply agreements, metering methods, remote monitoring, equipment capable of output control, the status of online integration, and records of past output control events can all affect future amounts of electricity sold. Because the electricity generated cannot always be sold in its entirety, we cross-check past generation records with sales records to verify the extent to which controls or shutdowns have had an impact.

Consistency of the documentation is also important. We check whether the power sales statements, meter-reading data, remote monitoring data, generation performance, and contract documents differ significantly. If there is an unusual drop in monthly generation or power sales, we determine whether it is due to weather effects, equipment shutdowns, output curtailment, or data loss caused by communication failures. The implications for price depend on the cause.

Whether the price of a used solar power plant looks reasonable depends on how realistically you can project future revenues. Therefore, confirming the power purchase terms and the remaining contract period is the first hurdle before buying. If you proceed while these are unclear, even detailed checks of equipment condition and management costs will leave the basis for your judgment unstable. First clarify the assumptions behind the revenue projections, and then proceed to verify generation performance and equipment condition.

Check 2: Verify power generation performance and causes of decline

Used solar power plants have historical generation data. This is a decision-making factor that newly built projects do not have.

If you can verify how much a plant has actually generated, you can identify site-specific trends that desk-based simulations alone cannot reveal. However, when reviewing generation records, it is important to check not only the annual total but also variations by month, season, equipment, and time of day.

Power generation is affected by the weather. Some years have many sunny days, while other years have many rainy or cloudy days. Therefore, if you judge based only on a single year’s results, you may be influenced by a year that happened to be unusually good or bad. When multiple years of actual performance can be confirmed, look at year-to-year variations, monthly trends, and drops during specific periods. If only a short period of performance is available, you need to carry out more thorough checks of the surrounding environment and the condition of the equipment.

What you need to watch in power generation performance is any decline that cannot be explained by seasonal factors alone. If generation falls at the same time every year, shading, snow accumulation, weeds, dirt, or output control may be involved. If generation suddenly drops, check for equipment shutdowns, poor connections, communication failures, tripped breakers, power conditioner failures, or stoppages during maintenance. If remote monitoring data is retained, you can trace shutdown times and abnormal event histories.

The effects of shading are an element that is easily overlooked in used power plants. Trees around the site that posed no problem at the time of construction may have grown and now cast shadows in the mornings, evenings, or during winter. Changes in the use of adjacent land can also result in new structures that affect power generation. If declines in power output are biased toward certain seasons or times of day, confirm the occurrence of shading on site and, if necessary, take differences in solar elevation into account when making a judgment.

Dirt and deposits also affect power output. Causes vary by region and environment: bird droppings, fallen leaves, soil dust, pollen, volcanic ash, and dust from nearby construction. If dirt on the panel surface is concentrated in certain areas, it can lead not only to reduced power output but also to localized overheating and degradation. Checking whether there is a cleaning history, or records showing an improvement in power output after cleaning, can help isolate the causes of the decline.

The state of weed management is also important. In ground-mounted solar power plants, when grass grows it can cast shadows on the panels, block inspection walkways, and hinder checks of fences and drainage facilities. At plants where mowing has been irregular, you need to check not only the impact on power generation but also the added difficulty of management and safety risks. Examine whether weed-control measures are in place, the maintenance frequency, and the work records, and consider how much effort will be required after purchase.

When reviewing power generation performance, pay attention to the difference between generation output and electricity sold. Even if power is being generated, output curtailment, equipment shutdowns, metering issues, or communication failures can prevent that generation from being reflected in the sales records. Also, if monitoring data is missing partway through, you need to confirm whether it is data loss or an actual outage. Even if the numbers appear to align, accurate assessment becomes difficult when the data acquisition method or the reporting period is unclear.

Power generation track records are useful material for assessing whether a price is reasonable, but they do not, by themselves, guarantee future revenue. Even if past performance has been good, future output may decline if equipment deterioration has progressed. Conversely, if past performance has been lackluster but the causes are clear and remediable, operational improvements after purchase may lead to better results. What matters is not just whether the numbers look good or bad, but being able to explain the reasons behind them.

Check 3: Confirm equipment condition and replacement risk

When judging the price of a used solar power plant, inspecting the condition of the equipment is indispensable. A plant continues to operate outdoors for many years after completion. It is exposed to various influences such as solar radiation, wind and rain, temperature changes, snowfall, salt damage, bird damage, weeds, and changes in the surrounding environment. Even if it appears to be operating externally, deterioration or malfunctions may be progressing inside the equipment.

The first thing to check is the condition of the solar panels. Check for cracks, chips, discoloration, dirt, frame distortion, loose mounting hardware, sagging cables, and similar issues. Even minor abnormalities on the panel surface can lead to reduced power generation or failures over the long term. During on-site inspections, it is important not only to check the appearance from a distance but also the condition of each row, shading patterns, and how the panels are secured to the racking.

Next, inspect the electrical equipment, such as power conditioners. In a solar power plant, the equipment that converts electricity generated as direct current (DC) and sends it to the grid plays an important role. These devices can be affected by aging, heat, humidity, dust, and the intrusion of insects or small animals. Check the history of abnormal shutdowns, repair history, parts replacement history, cooling conditions, installation environment, and surrounding ventilation.

When considering replacement risk, it is insufficient to adopt the view that “it’s operating now, so there’s no problem.” In used power plants, major equipment may need to be replaced or repaired at some point after purchase. Although it is difficult to predict exactly when and to what extent replacements will be required, you can form a reasonable outlook from years of operation, outage history, inspection records, and whether manufacturer warranties or maintenance contracts can be transferred. Even projects that appear cheap can become a substantial burden in practice if major repairs are required immediately after purchase.

The condition of the mounting structures and foundations is also important. Ground subsidence, tilting, loose bolts, corrosion, deformation, or poor drainage can affect the overall safety of the facility and its power generation efficiency. In power plants installed on slopes, reclaimed land, or embankments, it is especially necessary to check the flow of rainwater and the condition of the slope faces. Locations where water tends to pool after heavy rain, places showing traces of soil or sediment flow, and areas where the ground around the foundations has been scoured can lead to future management risks.

Cables, junction boxes, and collection equipment must not be overlooked. Deterioration of cable sheathing, loosened connections, damaged protective conduits, animal damage, and ingress of rainwater can lead to power generation stoppages or safety issues. Check whether inspection records include insulation measurements and electrical verification results, and what actions were taken if any abnormalities were found. For parts that are difficult to see on site, the presence or absence of records becomes an important basis for judgment.

Remote monitoring equipment and the communication environment should also be checked. To detect abnormalities at a power plant quickly, it is important that monitoring data can be acquired reliably. At plants where communications are prone to interruptions, detection of anomalies can be delayed and verification of actual performance data can become difficult. If monitoring equipment is old and its continued use is uncertain, you should also anticipate the effort involved in updating or replacing it.

When assessing equipment condition, we confirm not only on-site visual inspections but also past inspection reports, repair details, replacement records, anomaly histories, and photographic records. Power plants with records on file make it easier to track past maintenance and management and to develop post-purchase operational plans. On the other hand, when there are few or no records, it is necessary to investigate the current condition more thoroughly.

The price of a used solar power plant depends on how stably the equipment can be used going forward. Instead of focusing only on the upfront price, you can reach a more realistic judgment by factoring in the likelihood of replacements and repairs after purchase. Since checking the condition of the equipment involves many technical elements, it is important to increase the information available for decision-making by conducting on-site surveys and specialized inspections as needed.

Check 4: Verify land, rights, and contractual matters

A used solar power plant is not just a purchase of the generation equipment. In many cases, you will also take over the rights that support the facility — rights to use the land, use roads and access ways, install transmission equipment, access for maintenance work, and relationships with neighboring properties. Therefore, even if the price appears reasonable, you need to exercise caution if there are concerns about the land or contracts.

First, you should confirm the land's rights. Verify whether it is owned land, leased land, or whether usage rights such as surface rights or leasehold rights have been established. If it is leased land, confirm the contract term, renewal conditions, termination conditions, the possibility of rent revisions, the scope of restoration to the original condition, and whether the rights can be transferred to a successor. Whether the buyer can continue to use the site under the same conditions after the sale directly affects the value of the power plant.

Land boundaries are also important. Verify that the power generation equipment is properly contained within the site and that fences, mounting structures, cables, drainage facilities, and access/maintenance paths do not encroach on neighboring land. If you purchase with unclear boundaries, you may later need to coordinate with adjacent landowners. It is important to cross-check on-site boundary markers, survey maps, land-related documents, registration information, and contract drawings to confirm that the equipment layout matches the land boundaries.

Checking access and service roads is also essential. Power plants require regular access for mowing, inspections, repairs, and equipment replacement. Confirm whether vehicles can reach the site, whether there is sufficient width for work vehicles to pass, whether access uses someone else’s land, and whether passage permissions or contracts are in place. If equipment replacement becomes necessary, work can become difficult if large machinery or vehicles cannot get in.

Conditions related to drainage and land development are also part of land risk. If there are problems such as water pooling within the power plant, rainwater flowing onto neighboring properties, slopes prone to collapse, or drainage channels that clog easily, the post-purchase maintenance burden will increase. Confirm whether there has been damage from heavy rain or typhoons in the past, whether there is a history of repairs, and whether the drainage facilities are functioning. Even if the power generation equipment itself is operating normally, poor land conditions reduce the stability of long-term operation.

For contracts, check the maintenance management contract, power sales-related contracts, land use contract, remote monitoring contract, insurance contract, and memoranda with neighbors. Confirm whether the contract can be transferred or the name changed, whether there is remaining term, and what the conditions are upon cancellation. If there are verbal agreements without written contracts or operational rules known only to the seller, there is a risk that handover omissions may occur after purchase.

Neighborhood relations are another factor that must not be overlooked. Because a solar power plant is operated at the same location for a long time, it is desirable that relationships with nearby residents and adjacent landowners be stable. Check for any past troubles related to vegetation encroachment, complaints about reflected light, drainage, noise, access, and landscape. Even small complaints can become problems again when management changes after a purchase.

Confirmation of laws and permits is also necessary. Verify that filings and permits required at the time of installation, procedures related to development and site preparation, procedures concerning farmland and forest land, and procedures for electrical equipment have been properly carried out. Because the items that need to be checked vary depending on the region, scale, installation site, and regulatory classification, it is important to confirm not only the seller’s documents but also the presence and contents of related documents. If procedural deficiencies are discovered later, corrective measures and coordination with stakeholders may be required.

Risks related to land, rights, and contracts cannot be seen from the power generation figures alone. However, they are critical factors that determine the continuity of operations after purchase. The more attractive a price looks, the more carefully you need to check for any oversights in the rights and contractual arrangements. Even if the equipment is capable of generating power, if you cannot use the land reliably, the value as a power plant diminishes.

Check 5: Confirm maintenance and operating costs and future risks

When evaluating the price of a used solar power plant, it’s important to account not only for the upfront purchase burden but also for the operation and maintenance costs incurred after purchase. A plant is not something you buy and forget; to maintain stable power generation you need continuous management such as inspections, mowing, cleaning, monitoring, insurance, repairs, contract management, and reporting. If you overlook these costs and efforts, a price that looks reasonable on the surface can still lead to lower actual profitability.

When checking maintenance and management costs, understand the current management structure. Confirm who is conducting inspections, how frequently on-site checks are performed, how mowing and cleaning are carried out, and whether there is a response procedure for incidents. If management is outsourced to a management company, review the contract terms and the scope of services. If the scope of outsourcing is limited, the buyer may need to take additional measures.

Grass cutting and weed-control measures are important maintenance items for ground-mounted power plants. On land where weeds grow easily, insufficient maintenance frequency can lead to shading and reduced ease of maintenance. Even if weed-control sheets have been installed, repairs are necessary when there is deterioration, tearing, or grass intrusion from the edges. When using herbicides, consideration for the surrounding environment and neighboring properties is also required. Before purchase, confirm not only the on-site grass condition but also past maintenance records and the expected future workload.

The need for cleaning and inspection also varies by power plant. In some areas, rainfall easily washes away dirt, while in others soil dust and bird damage can cause soiling to persist. Sites near the sea may be affected by salt, and locations close to farmland or factories can be exposed to particulate dust. When cleaning is carried out, it is necessary to consider ease of access, securing water, worker safety, and the potential impact on panels and wiring.

As a future risk, it is also necessary to consider the timing of equipment replacements and repairs. Power conditioners, monitoring devices, electrical components, cables, fences, and racking peripheral materials may require replacement or repair during long-term operation. When you factor in the availability of replacement parts, whether there are contractors who can handle the work, and lost revenue from electricity sales during downtime, the impact on operations — not just the repair costs — becomes apparent.

Preparing for natural disasters is also important. The risks to consider vary by region and include typhoons, heavy rain, lightning strikes, snowfall, earthquakes, and landslides. Check past damage history, insurance enrollment status, coverage scope, deductible conditions, and records of recovery responses. Having insurance does not automatically provide peace of mind; it is important to verify what is actually covered and how long recovery will take.

Responses to output curtailment and regulatory changes should also be considered potential future risks. A power plant's revenue can be affected not only by contract terms but also by local grid conditions and operating rules. Check how extensive curtailment has been historically and whether there is uncertainty in the outlook going forward. Because regulations and rules may change, it's important to maintain flexibility to accommodate changes, not just rely on the conditions at the time of purchase.

You also need to think about the power plant’s exit strategy. After the feed-in tariff period ends, future burdens will vary depending on whether the facility will continue to be operated, be removed, be repurposed, or the land returned. For leased land, conditions for restoring the site to its original condition are especially important. In commercial solar power projects, you should confirm the status of funds set aside for disposal costs and related reporting, as well as the scope of responsibility for removal and disposal. If arrangements for removal, disposal, and land restoration are ambiguous, they can lead to disputes over future cost burdens.

The purpose of confirming maintenance costs and future risks is not to make you anxious about the purchase. By visualizing risks in advance, you can assess the reasonableness of the price more realistically. If a property remains profitable after factoring in the necessary maintenance and repair costs, it becomes easier to plan post-purchase operations. Conversely, properties with unclear management burdens should be treated cautiously, even if they look attractive based on price alone.

Don't judge by price alone — proceed with on-site inspections and data organization

The price of a used solar power plant cannot be judged by a single figure. You need to determine whether it is worth acquiring at that price by comprehensively assessing the power purchase terms, actual generation performance, equipment condition, land- and rights-related issues, operation and maintenance costs, and future risks. What is especially important for operational staff is to be able to organize and explain the verified information, rather than relying on intuitive comparisons.

We start by reviewing the documents. We collect documents related to power sales, generation performance, inspection records, repair history, equipment lists, drawings, land-related documents, contracts, insurance documents, and management records. Projects with complete documentation make it easier to trace past operational status and to plan post-purchase. For projects with missing documents, confirm the reasons for the gaps and supplement them with on-site surveys or additional verification.

Next, we will conduct an on-site inspection. Even if the documents show no problems, there are aspects at the site that are difficult to capture in numbers. Shadows from surrounding trees, the condition of weeds, drainage flow, damage to fences, tilt of the mounting structures, condition of cables, ease of use of the access road, and the proximity to neighboring properties are things that only become visible when confirmed on site. Because a power plant is an outdoor installation, it is affected by the local environment.

During on-site inspections, rather than just doing a single walkthrough of the entire power plant, it is easier to organize the assessment by separating elements related to power generation from those related to management. Elements related to power generation include panel orientation and tilt, shading, soiling, damage, and equipment downtime history. Elements related to management include access paths, ease of grass cutting, drainage, fencing, safety during inspections, and workspace for equipment replacement. By checking both, you can grasp profitability and operational burden simultaneously.

The information verified will be organized for purchase decision-making. For the price, clarify which conditions are positive factors and which are risk factors. Elements such as stable terms for electricity sales, a track record of power generation that can be continuously confirmed, well-maintained equipment records, clear land rights, and a location that is easy to manage provide supporting material for the decision. Conversely, elements such as unknown causes for generation decline, insufficient inspection records, ambiguous land contracts, and a significant future repair burden should be treated with caution.

When purchasing a used solar power plant, it is important for the buyer to have their own verification checklist and not rely solely on explanations from the seller or brokers. Even if explanations are thorough, whether they match the actual documents or on-site conditions is a separate matter. If there are any concerns, verify them before purchase and, if necessary, reflect them in the contract terms or handover conditions. Because problems discovered after purchase often leave limited options for recourse, it is important to reduce uncertainties as much as possible during the pre-purchase inspection stage.

Also, the reasonableness of the price depends on the buyer’s objectives. Whether you prioritize stable income, aim to increase revenues through management improvements, plan to hold the asset long-term, or consider future resale or repurposing will change the points you need to examine. The same power plant can be attractive to one buyer and pose significant risks to another. It is important to confirm that it fits your company’s operating structure and risk tolerance.

While a used solar power plant is an asset that is already operational, it is also an asset that inherits past operating conditions and future maintenance burdens. Although it may seem easier to compare by price alone, in reality there are significant differences in conditions from project to project, making them difficult to measure by the same yardstick. That is why it is necessary to check each of the basic items—power purchase terms, generation performance, equipment condition, land and contracts, and operation and maintenance—and make a comprehensive assessment.

If you carry out thorough pre-purchase checks, you will see not only whether the price is reasonable, but also what kind of management will be required after purchase, where there is room for improvement, and which risks should be prioritized for countermeasures. In practice, this upfront due diligence determines the operational quality after purchase. When considering a used solar power plant, rather than rushing to a conclusion based on the surface price, confirm the actual condition of the plant from both on-site inspection and data.