Is That "Approved" for Real
The Technical Checks Before You Buy a Grid-Scale Battery Storage Facility — 40+ Issues Across 9 Domains

01 — 640 MW and 172 GW: Where the Buyer Stands Today

Start with two numbers. As of the end of December 2025, grid-scale storage batteries actually connected to the grid totaled roughly 640 MW. Meanwhile, capacity under connection study reached about 172 GW, and capacity with connection-agreement applications pending about 30 GW (Agency for Natural Resources and Energy, Next-Generation Power Grid Working Group). That is roughly 270 times the connected capacity, piled up at the intake window.

What this gap means is simple. Most grid-scale battery projects brought to buyers today as "deals for sale" are not yet power plants. Land, some kind of grid-related paperwork, and a bundle of business plans — that is what the product actually is. Connection-agreement applications swelled to about 24 GW as of the end of September 2025, roughly 3.9 times in a single year (over the same period solar grew 1.1× and wind 0.8×), and a national advisory council acknowledged that "many applications exist for projects whose prospect of reaching commercial operation is unclear." That is precisely why, in 2026, the rules for grid connection are being amended in rapid succession.

The first job for a first-time storage buyer is not price negotiation. It is to pin down what stage the bundle of documents represents and how solid the rights are — and, reaching beyond the rights themselves to land, law, power contracts, equipment, the site, and the contractual vessel, to sort fact from claim. This article, written mainly with high-voltage-connected, 2 MW / 8 MWh standalone storage in mind, organizes that sorting into nine domains and more than forty issues. It runs long, but it is meant to be read while cross-checking the end-of-chapter checklists (numbered 01–43) against your own deal materials. Note that assessing profitability itself — assumptions about market prices, the reasonableness of returns — is out of scope here and left to a separate article (though Chapter 9 does cover whether the setup for accessing revenue can be confirmed; that falls within the technical check).

02 — The Standard of Judgment: The Primary-Evidence Rule, and Green · Yellow · Red

Before getting into the individual issues, set down two standards that run through the whole.

First, the primary-evidence rule. A seller's explanations run to a set repertoire: "We've consulted with the TDU." "The schedule is expected to be shortened." "We've briefed the residents." "The fire department says there's no problem." These are all claims, not facts. There is a single condition for becoming fact — being converted into paper (or data) issued by a third party: a written response from the transmission and distribution utility (TDU), inquiry responses or discussion records from the municipality or fire authority, transfer records and receipts, the property registry, actual measurement data. A claim that can't be converted is treated as "unconfirmed," regardless of whether the seller acts in bad faith.

Second, a three-color verdict. The result of checking becomes usable in practice when split into three, rather than a binary of complete/incomplete.

What matters is not waving Yellow through with "it'll probably be fine," and defining Red in advance. Not a checklist of "are the documents present," but "does the content of the documents cross the line that changes the verdict." For example, not whether an approval notice exists, but in whose name the approval stands and whether that position transfers to the buyer by contract. From here on, each chapter is written with this line in mind — where Yellow begins, and what turns it Red. The end-of-chapter checklists use the same "what to check / required evidence / Red" format as an actual DD, marked [Pre-deposit] [Pre-acquisition] — by which stage each must be confirmed.

03 — Grid Rights: Taking Apart "We Have the Connection Study Response"

A deal pitch almost invariably opens with the line "We've obtained the connection study response." Let's take that single sheet apart from eight angles.

(1) Authenticity of the response itself. Check the original and cross-reference it against OCCTO's latest form. The particulars — whether connection is possible, an outline of the works, the required construction period, a rough estimate of the cost contribution, and the validity period (one year in principle). If only a PDF copy appears, the possibility of alteration can't be ruled out. If in doubt, go as far as confirming existence through an inquiry to the transmission and distribution utility. An expired response is not a right — just paper.

(2) Pinning down the rights stage. The staircase toward confirmed interconnection has three steps: ① connection study answered → ② connection-agreement application filed (receipt notice) → ③ interconnection approved (approval notice). A connection study response answers feasibility and rough figures; it is not confirmed interconnection. In practice it's not uncommon for a step-① project to be spoken of as "approved" — and this should be treated not as a misunderstanding but as a misrepresentation, i.e., Red. Mistaking the step becomes, directly, a mistaking of the price.

Figure 1 | The three-step staircase toward confirmed interconnection and the corresponding documents. STEP 1 is a presentation of study results, not the securing of grid capacity.

(3) Evidence of money. If told "the deposit and cost contribution are paid," ask for transfer records and receipts on top of the contract. Here the 2026 rules bite. For connection-agreement applications received on or after April 2026, the deposit was raised to 10% of the estimated cost contribution (previously 5%), and where the contribution is paid in installments the first payment is at least 50%. In other words, the amount that should already have been sunk differs by the application's timing. A "paid" claim with no evidence warrants treatment much closer to Red than Yellow.

(4) Documenting verbal claims. "The schedule can likely be shortened," "we've consulted with the TDU" — many projects carry this kind of language in the business plan. The question to ask is whether it has been converted into a written TDU response or minutes of discussions. If not, strip that schedule or condition from the plan and re-evaluate. A P&L that bakes in an unsupported schedule reduction is not a P&L.

(5) Title holder and succession. The response and contracts should be in the name of the seller (or its affiliate/SPC). And that position — the connection agreement, the cost-contribution agreement, the generation-balancing supply agreement, membership in OCCTO — should be transferable to the buyer. Confirm the possibility and procedural requirements of transfer in writing via an inquiry to the transmission and distribution utility. A structure where transfer is impossible, or where the seller's cooperation is indispensable to transfer yet isn't a contractual obligation, leaves the buyer stranded after closing.

(6) Which side of the 2026 new rules. As measures against speculative capacity reservations, the discipline has stacked up: ① from January 5, 2026, applications must attach land survey results, the registry, and the like; ② from April that year, the aforementioned 10% deposit / 50% first payment; ③ from June that year, simultaneous filing of the discharge (generation-side) and charge (demand-side) applications became mandatory; ④ a duty to submit land-use-right documents within two months of interconnection approval (non-submission cancels the connection reservation); ⑤ from August 1, 2026, a cap on the number of connection studies that can be filed simultaneously in the same area. The implication for buyers: the obligations and deadlines owed differ by which rule the project's receipt/application date falls under. The evidence showing the receipt date has itself become a required document. And as the flip side of tighter rules, the scarcity of fully-documented projects has risen.

Figure 2 | The "capacity-squatting" measures stacked up in 2026. The project's receipt/application date determines which rule it falls under.

(7) The land-use-right time bomb. Item ④ in (6) is weighty enough to treat as a standalone check. A project that has obtained interconnection approval has its connection reservation cancelled if it can't produce documents evidencing land-use rights within two months of approval. For a project with this clock running mid-negotiation, you must track the prospect of completing the land contract against the days remaining, day by day. If there's no path to securing it within the deadline, that is Red.

(8) The substance of the connection — non-firm, curtailment, charging. Even when approved, the shape of the business changes with the connection terms. Whether it's a non-firm connection, its position under the priority-dispatch rules, the expected frequency of curtailment, the kW burden of generation-side charging, and the congestion of that area and grid. At chronically congested points, operation may not stand up even with perfect rights. This is the work of matching the terms section of the connection study response against the area's published information.

Checklist ① | Grid rights (No. 01–08). Confirm everything by "the name of a document."

04 — Land and Title: The Match on Paper, and What Lies Beyond the Boundary

Overlay. The starting point is overlaying the registry, cadastral map, and land survey against the equipment layout. Do the parcel number, land category, area, and actual conditions match? Draw the parcel lines onto the layout and you discover — only by doing this — a fence or access road spilling onto the neighboring parcel. If the land category is still farmland, it feeds straight into the conversion discussion (Chapter 5).

Boundaries. Whether there's a confirmed survey and a boundary-confirmation document. Place equipment while the boundary is unsettled and you carry the tinder for an encroachment dispute for 20 years. Land where a boundary dispute actually exists is Red on that alone.

Intrusion of third-party land. The classic oversight: legacy roads, blue-line waterways, channels, and blank strips between parcels. Match the cadastral map against the site to check these don't cut across the premises or access road. If they do, the difficulty depends on whether it's a public asset still functioning (a live waterway, say) or one that has lost its function; to receive a transfer, expect the process from use-abolition to run half a year to years, in practical terms. Identifying the owner/administrator requires inquiries to the municipality or the Finance Bureau.

Occupancy permit. Where the access road or wiring route involves occupying a river or road, the physical occupancy permit and whether it transfers. For a project where the permit was "lost," confirm with the permitting authority whether a reissue or renewal notice can substitute. An occupancy that can't be re-obtained is the same as the access road disappearing.

For leased land. The perfection requirements for the leasehold or superficies right (whether registered), mortgages in Section Otsu of the registry, and the landowner's consent to assignment/sublease. In particular, a structure on land carrying a senior mortgage where the consent of the landowner/mortgagee hasn't been obtained is treated as Red, because a single foreclosure erases the business foundation. Whether the rent-revision clause and contract term cover the 20-year business period is also examined here.

Checklist ② | Land and title (No. 09–13). The registry and cadastral map can be obtained by the buyer directly.

05 — Laws and Permits: In Light of the 2024–2026 Wave of Amendments

City Planning Act. A national notice dated April 8, 2025 (City Planning Division Notice No. 7) established that grid-scale storage batteries can fall under "Category 1 Specified Structures." Accompanied by grading of a certain scale, they become subject to a development permit, and in urbanization control areas a siting-criteria review applies (Article 34, item 14, etc.). The harshest case here is a control area where the municipality hasn't yet established review criteria. With no criteria, no permit can issue — currently, installation is impossible, i.e., Red. Municipalities are developing criteria in stages, and regional variation is enormous. Rather than "it should be buildable," make a written municipal response your evidence.

Fire and hazardous materials. Following the Fire and Disaster Management Agency's model-ordinance revision (effective January 2024), each municipality's fire-prevention ordinance changed the unit of regulation to kWh. Lithium-ion batteries generally require a filing above about 20 kWh, and depending on the stored volume, separation from buildings and the like (3 m is one benchmark) is required, or fire-spread-prevention measures where separation can't be achieved. How the capacities of multiple containers are aggregated, and similar points, vary in practice by jurisdictional fire authority; the evidence is a copy of the filing and records of pre-consultation. A project stuck at "under consultation" with unresolved insufficient separation cannot move forward. On top of this, because the electrolyte falls under hazardous materials (Class 4), depending on quantity it drags in regulation as a hazardous-materials facility and the appointment of a safety supervisor.

Electricity Business Act. As a storage facility, it needs a safety-regulation filing, appointment of a chief engineer, and pre-use self-confirmation. Worth knowing structurally: because the high-voltage 2 MW / 8 MWh class falls below the construction-plan-notification thresholds (10 MW output / 80 MWh capacity), unlike large extra-high-voltage projects it is exempt from the state-involved statutory checks — construction-plan notification, pre-use self-inspection, and safety-management review. Precisely because it's a scale with light statutory third-party checking, the assurance value of the buyer's own voluntary verification is relatively higher. An existing project running without a filing is beyond the pale — immediately Red.

Other siting matters. Depending on the candidate site: farmland conversion (Category 1 farmland is in principle non-convertible), forest-land development, regulated zones under the Fill Regulation Act, the three erosion-control laws, the River Act. Confirm with the physical permits; treat "application planned" as Yellow and evaluate it together with the schedule risk.

The template for this chapter is one thing. For matters with clear statutory standards, use the statute, notification, or permit. For matters with wide municipal discretion, use the written inquiry response. Leave not a single "probably fine."

Checklist ③ | Laws and permits (No. 14–17). For items with wide municipal discretion, make the written inquiry response — not a verbal statement — your evidence.

06 — Equipment Cybersecurity: Reading JC-STAR Through a Buyer's Eyes

Toward 2027, a new axis has been added to equipment selection: JC-STAR — the security-conformity labeling scheme for IoT products operated by IPA. With the revision of the technical requirements for grid connection (the grid code), regulatory development is proceeding in the direction that high and extra-high voltage will presuppose the use of ★1-compliant products from connection-agreement applications on or after April 2027 (low voltage under 50 kW from October that year). That the trigger is the "connection-agreement application" rather than the "connection date" bears directly on development schedules.

There are three things a buyer should nail down.

First, the meaning of the star levels. ★1 is 16 baseline requirements (mandatory change of the initial password, secure communication, proof of no known vulnerabilities, and so on), assessed by self-declaration of conformity. ★2 is also self-declaration; only at ★3/★4 does it switch to third-party certification. What's asked for grid connection for the time being is ★1; it is not a scheme where more stars are more advantageous for connection.

Figure 3 | JC-STAR conformity levels and assessment methods. ★1 and ★2 are declaration-based by the operator — which is exactly why the registration needs backing up.

Second, backing up — because it's self-declared. ★1 can be obtained on the operator's declaration. In other words, "it's ★1-compliant" is itself a claim. Cross-check whether the model number in question is actually listed on IPA's compliant-product list — here too the primary-evidence rule applies directly. Note also that conformity labels have a validity period (up to two years from issuance, extendable), which becomes a post-operation management item.

Third, drawing the line on in-scope equipment. The scope is "control-system equipment that uses IP communication," centered on the PCS and EMS, and can include the BMS, gateways, and so on. Both "make one gateway compliant and you dodge the whole thing" and "everything connected to the network needs it" are wrong. Pull the IP-communicating control equipment out of the project's equipment list and cross-check each one against the list.

The implication for a project you buy now is clear. Even for a project that reaches the connection-agreement application before April 2027, compliance status will invariably be asked at future expansion, equipment replacement, and — above all — resale. A project built from non-compliant equipment should be evaluated with replacement cost and schedule impact folded in, and in the world of subsidies, compliance has already begun to enter the grant requirements. The details of the scheme and its trigger point are explored in the JC-STAR explainer column.

Checklist ④ | Equipment security (No. 18–20). For now, a domain handled not by disqualification (Red) but by folding cost and schedule in.

07 — Equipment, Degradation, Capacity Warranty: Confirming — on Paper and by Measurement — That the Machine Lasts 20 Years

The real substance of a storage facility's value is, in the end, the battery. A project where this can't be confirmed means buying only the vessel.

Provenance of the cells. The maker — not just the company name, but mass-production track record, financial strength, and delivery record in Japan. The chemistry (LFP or NMC — ternary), and the year of manufacture. Ternary wins on energy density but behaves harshly in thermal runaway, raising the difficulty across fire consultation, insurance, and community briefings alike. That many domestic and overseas fire cases involve ternary is background a buyer should know. Cells also undergo calendar aging while sitting in the warehouse. Confirm the definition of "new" by date of manufacture.

The substance of the capacity warranty. What you check is not whether a warranty exists but the fine print. ① The warranty period and the SOH (state of health) guaranteed at end of life (EOL) — a warranty level below SOH 70% at EOL is a warning line, meaning the back half of the business thins out. ② The operating conditions premised for the warranty — annual cycle count, charge/discharge rate, SOC operating range, temperature conditions. Where this diverges from the actual operating plan (the aggregator's operating policy), the warranty becomes effectively a dead letter. A project with no capacity warranty, or with warranty terms left inconsistent with the operating plan, is at a level you may treat as Red.

For an operating project, the actual data. The primary evidence is sales and operating records — monthly revenue reports by market, bid/settlement data, imbalance records, availability. Because any equipment stoppage inevitably shows up in sales, this bundle of numbers alone reveals operating quality and equipment health to fair precision. Even to confirm SOH, you don't normally need to analyze the BMS raw logs — reports periodically issued by the maker or EMS, and the SOH figures reported under the capacity warranty, suffice. Being able to confirm by actual results rather than catalog values is the greatest advantage of buying an operating project; conversely, a seller reluctant to disclose the monthly revenue reports is itself a signal.

PCS and grid-side requirements. The certification status, whether the power-factor / FRT and other settings match the connection terms, and the parts-supply horizon and maintenance setup. The PCS is equipment whose replacement comes into view around years 10–15, and its cost and continuity of supply also weigh on the exit price.

The creditworthiness of the guarantor. Even a 20-year capacity warranty is paper if the guaranteeing entity doesn't exist ten years on. For an overseas maker, the substance and capital of its Japan entity; for an EPC, the backing of completion guarantees and defect liability. The equipment story, in the end, merges into the credit story (Chapter 10).

As-built documentation. As-built drawings, the single-line diagram, test reports, pre-use self-confirmation results. Where an existing project lacks these, you keep paying the "no drawings" cost at every future retrofit or remediation. The gap in maintenance responsibility at the operating stage is detailed in "When the Storage Facility Goes Down, Who Fixes It?"

Checklist ⑤ | Equipment, degradation, warranty (No. 21–26). Read the warranty's fine print, not its "presence."

08 — What Only the Site Can Tell You: Neighbors, Noise, Delivery Access, Ground

This is the domain most often missed in desk-based document checks and most bitterly disputed after purchase.

Evidence of community consent. Open up the substance of "we've briefed them." When, to whom, and what was explained — the invitation, attendance records, minutes, the Q&A record, consent forms. For consent forms, whose consent is the crux; adjacent landowners and the neighborhood association mean different things. A briefing with neither paper nor recording is safest approached as one that never happened. On top of this, investigate whether that area has had past opposition movements against solar or other storage. For the 20 years after operation begins, it is the buyer, not the seller, who remains the area's neighbor.

Quantifying noise. Cooling fans and the PCS don't stop at night either. Noise regulation is set by the municipality by time band according to land use, and the strictest night-time band lands around 40–45 dB in residential areas (evaluated at the property boundary). Start with reality. A distance cutoff of "if it's ◯ m from a home, I can buy it" doesn't work. Cut by distance and almost no high-voltage-class projects remain — precisely because small sites near homes are the typical location for this class. So the verdict line is not distance but the distance-scaled trio: ① a predictive calculation against the night-time standard based on the equipment's noise-source data (mandatory the closer it is), ② whether the mitigation to meet the prediction — layout, sound barriers, low-noise models — is folded into the design and cost, and ③ evidence of resident briefing and, especially, consent of adjacent landowners. The distance to the nearest home is not the "buy / don't buy" criterion but a dial that raises the level of evidence required — the closer it is, the more the demand escalates from prediction to measurement, from briefing to individual consent. Even so, if a night-time-standard exceedance can't be resolved by mitigation — that alone is the walk-away line. This issue is detailed in the standalone column on noise.

The delivery route. Battery containers and transformers are heavy loads — 40-ft-container class, tens of tons gross — carried on 16-m-class trailers. The width and corner cuts of the fronting road, the turning trace at intersections, the load capacity of bridges along the route (weight-limit signs), the height of power lines and overpasses, and whether an oversized-vehicle transit permit is needed and how long it takes to obtain. For a project where the final segment is a private or farm road, look as far as passage consent and whether reinforcement is needed. Much of this can't be known from a desk map; a drive-through is the sure way. Land that can't be delivered to won't become a storage facility, however perfect the rights.

Ground and hazards. The flood, inland-flooding, landslide, and tsunami hazard maps, and the foundation / ground-level design against the assumed inundation depth. The basis for bearing capacity (the geotechnical report). If grading is involved, the relationship to fill-regulated zones. Land with assumed inundation can sometimes be handled by design, but it will surely rebound onto insurance premiums and financing terms.

The date on site photos. It sounds petty, but check whether the site photos in the deal materials carry a shot date. Half-year-old photos don't reveal current conditions. Only when coordinates, parcel number, photo, and actual conditions all match can you finally talk about "that land."

Checklist ⑥ | Site (No. 27–31). This domain alone: always stand on the site, together with the documents.

09 — Power Contracts and Market Access: The Balancing & Supply Agreements the Aggregator Drives

As stated at the outset, assessing the reasonableness of revenue amounts is out of scope here. However, whether the setup for accessing revenue actually exists is within the technical check. And this setup is made not of abstractions but of a concrete bundle of contracts and applications.

Understanding the structure. The high-voltage 2 MW class can't, on its own, reach the minimum bid capacity of the capacity market or the Long-term Decarbonization Auction (30 MW for storage). The revenue pillar is therefore operation in the balancing and wholesale markets via an aggregator. That is, for storage of this class, the aggregator is not an option but a precondition.

The contract's dual nature — discharge is generation, charge is demand. A storage facility wears two faces under the rules. When discharging, as a generator, it must enter the framework of a generation-balancing supply agreement (the "balancing agreement") with the transmission and distribution utility, and normally the aggregator becomes the counterparty as the representative of the generation balancing group (the generation contractor). When charging, it is on the demand side and needs a supply agreement with a retail electricity provider to procure charging power (sometimes the aggregator provides this integrated with its group's retail arm). The June 2026 "simultaneous filing" requirement seen in Chapter 3 (6) is precisely this dual nature codified as a rule — a storage facility comes into being only when both the discharge-side and charge-side applications are in place. What the buyer must confirm is the sorting of each of these contracts: in whose name, transferred, or re-concluded anew on the buyer's side.

The paperwork the aggregator drives. By the start of operation, procedures on the aggregator's (specified wholesale supply provider's) side run in parallel: enrollment in the balancing group, metering and grid-point setup (switching), the setup for submitting scheduled-balancing plans, and — if participating in the balancing market — EPRX trading membership plus the per-product pre-screening and performance-verification testing (testing whether it can actually respond to dispatch), and building the communications, whether a dedicated line or a simplified dispatch system. These are hard for the buyer to see on paper, but if any one is incomplete, revenue won't begin even when the equipment is finished. Because preparation takes months, whether these steps are on the operation-start schedule is itself a check item.

Checklist ⑦ | Power contracts and procedures (No. 32–39). Names and forms differ by transmission and distribution utility and by product, so confirm each in writing individually. Any one incomplete produces "finished but can't earn."

The substance of the aggregator contract itself. Whether there is an aggregator contract (or a high-probability commitment). "We'll decide by operation start" means the revenue pillar is blank. If there is a contract — whether the counterparty is a registered specified-wholesale-supply provider, which products it can handle (how far across primary–tertiary reserve), the communication requirement (dedicated line or simplified dispatch system), and JC-STAR compliance of the control gateway. An aggregator handling primary reserve may specify the PCS / EMS combinations it can support, and whether the project's equipment configuration matches that specification is nailed down with the aggregator's confirmation letter. As for the fee rate, confirm the calculation basis rather than the number itself. Whether it's a rate on gross market revenue or on net after cost deductions changes the take-home entirely. Clauses on early termination and resource substitution are also essential, given the possibility of switching aggregators over 20 years.

Freshness of the assumptions. In 2026 the balancing market moved on three axes at once — a lowered price cap (¥19.51 → ¥15 per ΔkW per 30 min, with staged cuts to ¥10 and ¥7.21 already designed if competition doesn't improve), a shrunken procurement volume (from ~3σ to ~1σ equivalent), and a doubling of the trading fee. Whether the project's business plan is built on these post-revision assumptions — don't simply trust a plan drawn at the pre-revision rate. This is not an assessment of yield but a freshness check on the plan.

Consistency with grid-side conditions. The non-firm connection, curtailment, and area congestion seen in Chapter 3 (8) converge here. At chronically congested points, however excellent the aggregator, the room to move is thin. Always read the connection terms and the operating plan as a set.

10 — Contract, Credit, Decommissioning: Where the Buyer's Questions Concentrate Most

Even with sound rights, land, and equipment, a loose contractual vessel leaves the buyer unprotected. In actual sale negotiations, this is in fact the domain where the buyer's questions concentrate most. (The overall picture of the contracts a storage facility concludes after operation begins is covered in the companion piece "Contract Design Decides ¥200 Million Over 20 Years".)

The structure of the deposit. Whether it's protected (segregated management, escrow, etc.). Whether there's a refund clause for a no-fault collapse — interconnection failure, permitting failure, expiry of the land-use-right deadline. A structure demanding a large deposit — say 40% of the purchase price — with neither protection nor a refund clause is itself a disqualifier-level red flag. Since a rights-stage project's probability of collapse is not zero, whether the design returns the money on collapse all but decides the quality of the contractual vessel.

How the termination conditions are written. "If the cost contribution rises more than ◯% above the estimate," "if the connection schedule slips more than ◯ months" — whether it's written in numeric thresholds of amount and period, not best-efforts clauses. Cost contributions and schedules move. Deciding the exit in numbers in advance, for when they move, is the job of the contract; a contract vague here is the same as shifting all the variability risk onto the buyer.

Credit. The finances of the seller, EPC, and SPC. Representations and warranties and capacity guarantees are merely promises premised on the survival of the party making them. To name one typical danger structure — a project where the SPC's capital is below the estimated decommissioning cost, with no reserve measures (fund or guarantee) for it. In that case, structurally, there is nowhere for the decommissioning cost 20 years hence to come from.

The reality of decommissioning. The external-reserve system for disposal costs that exists under solar FIT does not apply to non-FIT storage. Processing lithium-ion batteries demands stricter management than ordinary industrial waste, and at present there's virtually no reliable published market rate for decommissioning unit costs. The only means of confirmation is a deal-specific decommissioning estimate. For a project where no estimate exists, decommissioning cost is "unknown" — and you can't debate credit while it stays unknown.

How to use Yellow. The Yellows raised in each chapter above — undocumented, unconsulted, inconsistent warranty terms — are not to be left alone but are material to convert into conditions precedent, price adjustments, and representations and warranties. Only when the DD's findings are reflected in contract clauses and price does the checking become protection for the buyer.

Checklist ⑧ | Contract, credit, decommissioning (No. 40–43). Don't leave Yellows alone; convert them into conditions precedent, price, and representations and warranties.

Conclusion — How Far to Do It Yourself, and Where to Bring in a Third Party

We've now looked through nine domains and 43 issues. Finally, let's organize how to run the whole thing.

Split it into two stages. What's practically reasonable is to split the checking into two stages. Stage one is desk screening before paying the deposit — centered, in this article's terms, on the document-based Chapters 3–6, quickly determining in a short span only whether any fatal wounds (Red) exist. Stage two is the full investigation before acquisition (closing) — digging deep, including site, measurement, credit, and quantitative assessment. The idea is to match the depth of checking to the timing of the buyer's decision. The [Pre-deposit] [Pre-acquisition] marks on the right edge of each checklist are the guide to which of the two stages to confirm in ("Pre-deposit + Pre-acquisition" means items to size up at the desk and re-verify on site and by measurement). Put the other way: you must not pay the deposit while even one Red is visible.

Signs to stop immediately. Bundling the disqualifiers of each chapter into nine.

What you can do yourself. Confirming the existence of, and requesting, the documents listed in this article — saying "please produce it." Matching against public information — hazard maps, land-use zoning, OCCTO's forms, IPA's compliant-product list. And recording the documents that don't appear and the questions that can't be answered. Making the question list itself becomes the first filter that sifts projects. Use the list below as the underlay for that question list.

Document-request list | Send this list to the seller first. The list of "documents that don't appear" becomes, as is, the list of the project's risks.

What's hard to do yourself. Inquiries to the transmission and distribution utility, municipality, jurisdictional fire authority, and Finance Bureau, and collecting their written responses. Standing on the site to verify residents, noise, delivery, and ground, and taking measurements. Credit assessment of the seller, EPC, and SPC. Quantitative work like noise prediction, SOH assessment, and verifying the consistency of warranty terms with the operating plan. And above all, finishing all of this inside the deadline that is the deposit due date. Each item, investigated, is knowable. Closing out 43 issues within the deadline, without gaps, on an evidence basis, is what's hard to do on the side.

In buying a storage facility, "peace of mind" is not meeting an agreeable seller, nor buying below market. It is the state in which verbal claims have been replaced by primary evidence, Yellows converted into contract clauses, and the absence of Red confirmed — that is what peace of mind actually is. And the work of performing this verification, within the deadline of the purchase decision, systematically, through the eyes of a disinterested third party, has a name. It is technical due diligence.

Use this article as the overall map of that, and as the underlay for your questions to the seller. You don't have to shoulder everything yourself. But the one job the buyer must not let go of to the very end is the distinction alone — what has been confirmed by evidence, and what still remains a verbal claim.

* This article is informational, based on regulatory information as of July 2026, and is not intended to evaluate any specific deal or solicit any particular transaction. Some figures in the text, such as "SOH 70%," include practical rules of thumb rather than statutory standards. Noise is framed to be judged not by distance to the nearest home but by compliance with the night-time standard together with documented mitigation and consent. The title holders and forms for power contracts and applications differ by transmission and distribution utility and by market product. Together with items that vary widely by municipality, jurisdictional fire authority, and prefecture, always confirm through individual written inquiries. Because the rules continue to be revised, base any application judgment on the latest primary sources.

Principal primary sources (confirmed as of July 2026)
· Agency for Natural Resources and Energy, Next-Generation Power Grid Working Group, 6th–10th sessions (December 2025 – June 2026): status of grid-connected capacity, connection studies, and contract applications; measures against speculative capacity reservations (mandatory attachment of land documents, 10% deposit / 50% first payment, mandatory simultaneous filing, deadline for land-use-right documents, cap on the number of connection studies)
· OCCTO: disclosures on grid-access operations for generation facilities, "Flow of Grid Access for Generation Facilities," and various forms (format & validity period of the connection study response; positioning of the generation-balancing supply agreement)
· MLIT, City Planning Division Notice No. 7 (April 8, 2025): treatment of grid-scale storage batteries as Category 1 Specified Structures and the handling of development permits
· Fire and Disaster Management Agency, Notification No. 7 of 2023 and others (effective January 1, 2024): shift of storage-battery regulation under fire-prevention ordinances to a kWh basis
· Electricity Business Act and its enforcement regulations: safety regulations, chief engineer, and pre-use self-confirmation for storage facilities; construction-plan-notification thresholds (10 MW output / 80 MWh capacity)
· OCCTO, Grid Code Study Group, 20th & 21st sessions (December 16, 2025; March 31, 2026): direction toward requiring JC-STAR ★1-compliant equipment for grid connection (high & extra-high voltage from April 2027, low voltage from October 2027, triggered by the connection-agreement application)
· IPA, "JC-STAR (security-requirement conformity assessment and labeling scheme)" program information & compliant-product list
· EPRX: trading rules, membership qualifications, and the guidelines for pre-screening / performance-verification testing
· Agency for Natural Resources and Energy, Institutional Design Subcommittee, 108th–110th sessions (October 2025 – January 2026): revisions to the balancing market's price cap and procurement volume