Japan Solar: Sotsu-FIT & Asset Sales
公開日：2026-08-22
The Sotsu-FIT Cliff: What Changes After 2026
If you own a solar plant in Japan that secured Feed-in-Tariff (FIT) approval under the old 20-year contract, you are approaching what the industry calls the "sotsu-FIT" (卒FIT) period. This simply means your original 20-year purchase obligation from a utility is ending. For plants commissioned in 2006–2007, this already happened; for the bulk of the 2012–2014 boom, the cliff arrives between 2032 and 2034. However, many early 10-year contracts (for smaller residential systems) have already crossed this line.
The critical point is that after the FIT period ends, you are no longer guaranteed the fixed purchase price. You transition to the "out-FIT" market, where you must sell electricity on the wholesale market, to a new retailer, or through a corporate PPA. The price you get will be significantly lower—often 20% to 40% of your original FIT tariff, depending on your region and the time of day you generate. This is not a failure; it is a structural shift. Your plant's profitability now depends on operational efficiency, not a government-backed tariff.
For non-Japanese owners, the most common mistake is assuming the FIT end date is the same as your contract's "operation start date." It is not always. Check your original "認定" (certificate) and the utility's purchase agreement. Some plants had a "deemed" start date before grid connection. If you misread this, you might plan for two more years of FIT revenue that you do not actually have. Your first step is to pull the exact contract and calculate the precise month of expiry.
Why Output Decline is Your Biggest Hidden Threat
After 10–12 years of operation, most solar plants in Japan show a degradation rate of 0.5% to 1.0% per year. That sounds minor, but cumulative loss by year 15 is 7–15%. However, the real output decline is rarely from module degradation alone. The bigger culprit is soiling, vegetation shading, and micro-crack propagation from typhoon stress. Japan's high humidity and frequent typhoons accelerate these issues compared to drier climates.
Many owners only look at the monthly inverter log and see a "normal" curve. But they ignore the performance ratio (PR). A healthy plant in Japan should have a PR of 0.80–0.85. If your PR has dropped to 0.70 or below, you are losing 15% or more of your revenue. This is not a technical nuance; it is a direct cash flow problem. A 1 MW plant generating at a PR of 0.70 instead of 0.80 loses roughly 100,000 kWh per year—at ¥12/kWh, that is ¥1.2 million annually.
The cause is often simple: string-level monitoring is absent, or the owner has never done an IV curve test. After 10 years, you cannot rely on the original installer's assumptions. Trees have grown, panels have discolored, and connectors may have corroded. If you plan to sell the asset, the buyer will perform a due diligence check on your actual output data. If your data shows a steady decline without a clear cause, the buyer will discount your asset value by 10–20%.
The Mandatory 10-Year Inspection: Not a Formality
Under Japan's Electrical Equipment Safety Law (電気用品安全法) and the Fire Service Act, your solar plant requires a specific inspection at the 10-year mark. This is not the same as the annual "点検" (inspection) you may have done. The 10-year inspection involves a full electrical insulation test, ground resistance measurement, and a visual check of all DC cabling and connectors. For plants over 2,000 kW, you also need a licensed electrical engineer (電気主任技術者) to sign off.
The cost is not trivial—typically ¥500,000 to ¥1,500,000 depending on plant size and access difficulty. But skipping it is worse. If you fail the inspection, your utility can refuse to purchase your electricity, even under FIT. For out-FIT sales, the buyer (retailer or PPA counterparty) will require proof of a passed inspection. If you are planning an asset sale, a failed 10-year inspection is a deal-breaker. Buyers will either walk away or demand a price reduction far exceeding the inspection cost.
A practical note: the inspection must be done by a third-party contractor registered with the Ministry of Economy, Trade and Industry (METI). Many foreign owners mistakenly ask their original EPC contractor to do it. That is allowed, but it must be independent of the daily O&M provider to avoid a conflict of interest. Get the written report in Japanese and have it translated. Keep it in your asset file. This report is your "health certificate" for any future transaction.
Asset Sale: How to Price Your Plant Post-FIT
If you are considering selling your solar plant before or after the sotsu-FIT date, the valuation method changes dramatically. Under FIT, the price was based on a discounted cash flow (DCF) of a fixed tariff for 20 years. Post-FIT, the valuation is based on your plant's actual output, the local wholesale price (JEPX), and your ability to secure a long-term off-take agreement. Buyers are currently paying 10–15x annual EBITDA for FIT assets, but only 6–8x for out-FIT assets with no PPA.
The Japanese market has seen a surge of foreign funds and domestic infrastructure funds buying sotsu-FIT assets. They are not buying the panels; they are buying the land lease, the grid connection, and the operational track record. Therefore, your asset's value is highly sensitive to three things: (1) the remaining land lease term, (2) the grid connection capacity and curtailment history, and (3) your O&M contract terms. If your land lease has only 5 years left, the buyer will heavily discount the price. If you have a long-term O&M contract with a reputable firm, that adds value.
To maximize your sale price, do not wait until the FIT expiry to start the process. Begin 12–18 months in advance. First, complete the 10-year inspection and fix any findings. Second, obtain a third-party output assessment (発電量評価) that projects future generation based on real weather data and your plant's degradation curve. Third, if possible, sign a short-term out-FIT PPA (1–2 years) to show you have a revenue stream post-FIT. This reduces the buyer's perceived risk and can add 5–10% to your sale price.
Practical Steps for Non-Japanese Owners
Your language barrier is your biggest operational risk. Most Japanese O&M contractors will not proactively explain the nuances of the sotsu-FIT market or the 10-year inspection requirements. They assume you know. To protect your asset, you need a bilingual advisor or a trusted local partner who can read the utility notices and METI announcements. The Japanese government periodically changes rules on out-FIT trading, and ignorance is not a defense.
Start by creating a simple asset file: your FIT certificate, the utility purchase agreement, all inspection reports, and your monthly output logs. Then, schedule a one-time independent audit of your plant's condition. This audit should include an IV curve test on at least 10% of your strings, a thermal drone scan, and a review of your inverter efficiency. This costs around ¥200,000–¥400,000 but will give you a clear picture of your plant's true health. Without this baseline, you cannot negotiate a fair O&M contract or a sale price.
Finally, do not panic about the output decline. A 1% annual degradation is normal. The key is to separate normal degradation from preventable losses. If you find that your PR is below 0.78, invest in a professional cleaning schedule and trim vegetation. These are low-cost fixes with a high return. The sotsu-FIT period is not the end of your investment; it is the beginning of a new, more disciplined phase. The owners who succeed are those who start with accurately understanding their plant's condition—not those who guess based on past FIT revenue.