Process and the grid

Permission to operate: the step nobody explains

The panels are up, the inspector has been and gone, and you have been told not to switch it on. This is why.

Updated September 2026 · Data as of Utility tariffs and federal orders read on 2 September 2026

Written by HyreSolar Research team Research and analysis

Audited by HyreSolar Research team Data audit and fact check

30 business days, in the one tariff that sets a deadline From the last of three preconditions

3 things the utility must have before the clock starts Conjunctive, not alternatives

None deemed-approval clause Silence is never a yes

The short answer

Permission to Operate is your utility's authorisation to energise the system, and it is a different approval from your city's electrical inspection. The two are in series, not in parallel: in the one tariff we found that defines PTO by name, evidence of the final electrical inspection clearance is one of three things the utility must receive before its clock starts at all. That tariff, PG&E's Electric Rule 21, says the approval "shall normally be processed not later than thirty (30) Business Days" after the utility receives all three of a completed interconnection request with payments, a signed interconnection agreement, and that inspection clearance. If the utility misses it, it must notify you and the state commission. There is no deemed approval, so silence never becomes a yes. And this is one utility's tariff, not a national rule.

Four approvals, and only one of them is PTO

Building or electrical permit: Issued by your local authority before work starts. Permission to build the thing.
Final electrical inspection: Your city or county inspector confirming the installation meets the electrical code your jurisdiction has adopted. Permission to say the work is done correctly. This is not PTO.
Interconnection agreement: A signed contract between you and the utility governing how your system connects to and behaves on their network. Permission to be attached.
Permission to Operate: The utility’s authorisation to actually energise and run the system. In the tariff we read it is defined as "Distribution Provider approval for Interconnection", and the Distribution Provider is the utility, not the city. Permission to switch on.
Authority Having Jurisdiction (AHJ): The formal name for whichever local body inspects and signs off. The tariff phrase is "the Governmental Authority having jurisdiction over the Generating Facility". Usually your city or county building department.

The sequencing that explains the wait

The most common misunderstanding about this stage is that the city inspection and the utility approval happen alongside each other, and that once the inspector signs off you are nearly done. In at least one tariff we can point to, that is precisely backwards.

PG&E's Electric Rule 21 lists three things the utility must receive before it will process an approval: a completed interconnection request including all supporting documents and required payments; a completed and signed Generator Interconnection Agreement; and evidence of the applicant's final electric inspection clearance from the Governmental Authority having jurisdiction.

The tariff's own wording is conjunctive. The thirty-business-day period runs "following Distribution Provider's receipt of 1)… 2)… and 3)…". All three. Which means the clock does not begin when your inspection passes. It begins when the last of the three arrives, and if the inspection clearance is the last one, that is when your utility's own review starts from zero.

So the two approvals are in series. Your inspector's sign-off is not the end of the process, it is an input to the next stage of it. A homeowner who has been told "the inspection passed" and expects to be running that week has been given a true fact with the wrong implication.

The tariff even anticipates the delay this creates. For projects likely to be complicated, it advises filing the interconnection request before inspection clearance and up to six months ahead of the target operation date, precisely so the two processes are not fully sequential.

What has to happen, in order

Before work
Permit issued
Your local authority authorises the installation. The code edition that applies is generally the one in force when the permit issues, which is why two identical systems can be held to different rules.
Installation
The system goes up
Physically complete, and switched off. It is not yet lawful to run it.
Any time
Interconnection request filed
With supporting documents and payments. This can and often should run in parallel with the build rather than after it.
After review
Interconnection agreement signed
The contract governing how your system behaves on the network. One of the three preconditions.
After installation
Final electrical inspection
The AHJ inspects and, if it passes, issues clearance. This is the step people mistake for the finish line.
The clock starts
The utility receives all three
Not before. In the tariff we read, the thirty business days begin here, on receipt of the last of the three items.
Within 30 business days
Permission to Operate
The utility’s approval. On a miss, it must notify you and the state commission with a reason and an expected completion date.
Then, and only then
Switch on
Running the system before PTO is generally a breach of your interconnection terms, whatever the hardware is capable of.

Business days, and no deemed approval

Two features of that thirty-day figure change what it means on a calendar.

It is thirty business days, not thirty days. Thirty business days is roughly six weeks of wall-clock time before any holiday is counted. Every timing figure in this tariff is expressed the same way, and converting them loosely is how a six-week expectation becomes a four-week one.

There is no deemed-approval clause. We looked for one. Some regulatory schemes provide that if an authority fails to respond within a window, the application is treated as granted; several state HOA solar statutes work exactly that way. This tariff does not. Missing the deadline obliges the utility to notify you and the state commission with a reason and an expected completion date, and that is all it does. Silence never becomes a yes.

The practical value of the deadline is therefore as a reference point rather than a guarantee. It tells you when to start asking, and it tells you that the utility owes the regulator an explanation, which is a more useful thing to be able to cite than most people realise.

Why residential interconnection is not a federal matter

A great deal of writing about solar interconnection reaches for federal sources, and it is worth explaining why they are the wrong documents, because it also explains why your experience differs so much from your cousin's in the next state.

The Federal Energy Regulatory Commission addressed this directly. In its 2020 order on distributed energy resources, it stated: "we decline to exercise our jurisdiction over the interconnections of distributed energy resources to distribution facilities for the purpose of participating in RTO/ISO markets exclusively as part of a distributed energy resource aggregation. Thus, we will not require standard interconnection procedures and agreements or wholesale distribution tariffs for such interconnections."

It then set out the boundary and where authority lands instead. Under what the order calls the "first use" test, an interconnection to a distribution facility that is not already used to transmit energy in interstate commerce falls outside federal jurisdiction, and, in the order's words, "such interconnections are governed by the applicable state or local law."

A rooftop system behind your own retail meter is not making a wholesale sale and is not connecting to a federally jurisdictional facility. So the rules that govern it are your state commission's and your utility's, and there are thousands of utilities.

That is the real reason there is no national answer to "how long does PTO take". There is no national rule to answer it with.

The four layers, and who writes each

Layer	Who writes it	What it governs	Binding on you?
Federal orders	FERC	Wholesale markets and transmission-level interconnection	Generally not for a rooftop system
State commission rule	Your state’s public utilities commission	The framework utilities must interconnect under	Yes, through your utility’s tariff
Utility tariff	The individual utility, filed with the state commission	The actual procedures, screens and deadlines	Yes. This is the document that governs your timeline
Technical standards	IEEE and UL, private consensus bodies	How equipment must behave and be certified	Only once a state rule or tariff adopts them
The electrical code	NFPA, adopted state by state	What the inspection checks against	Yes, in whichever edition your state has adopted

Layer structure established from FERC Order No. 2222, a CPUC-approved utility tariff, and a state administrative code adopting the electrical code by reference.

The row that matters to your timeline is the tariff, and it is the one almost nobody reads. It is a public document your utility must publish.

The standards behind the approval, and why an old inverter fails

Two private standards sit underneath most of this, and they are worth naming because they explain a specific failure mode.

IEEE 1547 is the interconnection standard. The current base edition was published in April 2018 and carries an amendment from 2020. It sets how a distributed resource must behave when connected: performance, operation, testing, safety, power quality and islanding. The 2018 edition made certain behaviours mandatory and settable rather than fixed, and the tariff we read implements exactly that, specifying default voltage and frequency ride-through settings and allowing the utility to re-tune reactive power settings per project where studies require it.

UL 1741 is the certification standard that equipment is tested against, with supplements corresponding to different revisions. The tariff treats plain UL 1741 and its later supplement under different sections with different requirements, which is not a formality.

Here is the consequence. That tariff states that certification "is a prerequisite for inverters installed after September 8, 2017". An inverter certified only to an older revision, or not certified at all, can therefore fail an interconnection review on paper regardless of whether it works. If a proposal specifies equipment, it is worth confirming the certification matches what your utility's current tariff requires, because that is a documentation problem discovered at the worst possible moment.

One honest note on a claim you will see everywhere. It is widely written that the older standard required inverters to disconnect on a grid disturbance and the 2018 edition requires them to ride through it. We could not verify the pre-2018 text at the standard of evidence used on this site, so we are not repeating it as fact. What we did verify is that ride-through behaviours are mandated and settable under the current regime.

What to do while you are waiting

1
Find out which of the three items is outstanding
The clock cannot start until all three are with the utility. Ask your installer, specifically, which of the interconnection request, the signed agreement and the inspection clearance the utility has received and on what date. A vague "we submitted it" is not an answer to that question.
2
Get the date the last item was received
That is the date any deadline runs from. Without it you cannot tell whether you are early, on time or overdue, and neither can anyone you escalate to.
3
Read your own utility’s tariff
It is a public document and it is the thing that actually governs your timeline. Search your utility’s name and "Rule 21" or "interconnection tariff". If it sets a processing standard, you now have a reference point. If it does not, that is worth knowing too.
4
Do not switch the system on
Running before authorisation is generally a breach of your interconnection terms whatever the hardware permits. It also gives anyone you later need something from a reason to say no.
5
Check whether your billing period has started
Your first statement may span a period before authorisation, which makes it useless as a measure of how the system performs. Note the authorisation date so you can read the bill against it.
6
Escalate to the regulator if the deadline passes
Where a tariff sets a processing standard, missing it may oblige the utility to report the delay to the state commission. Knowing the tariff section number and the receipt date turns a complaint into a specific question, which is a materially different conversation.

Method and limitations

The most important limitation on this page

Every specific figure here comes from one utility's tariff. It is PG&E's Electric Rule 21, filed with and approved by the California Public Utilities Commission. It is not California law, it is not how the other large California utilities work, since each files its own, and it is certainly not a national standard.

We used it because it is the only document we found that defines Permission to Operate by name and attaches a processing standard to it, which makes it the best available illustration of what this stage actually consists of. Treat the structure as instructive and the numbers as specific to that utility.

We attempted to verify interconnection rules in New York, Texas, Arizona, Massachusetts and New Jersey. Every one of those sources refused automated retrieval, and the usual archive workaround was unavailable throughout. No state other than California was verified, and this page asserts nothing about any other.

What we deliberately do not state

Any electrical code provision text. The specific requirements most often cited in solar writing, including the rapid shutdown rule and the busbar percentage rule, could not be read from any authoritative source. The code publisher's free portal is a JavaScript application that returns no text, and the only version we found was a machine-generated summary on a republisher's site, disclaimed by that site and specific to an edition. We would rather say nothing than print a code number we have not read.

Any meter-exchange window. We looked for a tariff provision setting one and did not find it. It is a real step and it takes real time; we simply cannot tell you how long it is supposed to take.

Any typical PTO duration. We have one utility's processing standard, which is what the tariff says should normally happen, not a measurement of what does happen. Those are different claims and we are only making the first.

Two things that may already have changed

A rulemaking opened at the California commission in August 2025 may revise the rule this page draws on. And an expedited dispute-resolution process that once existed alongside it has been suspended following a funding lapse, so it should not be relied on. Check the current tariff rather than this page if a real deadline matters.

Not legal advice

This describes a public tariff and a federal order. Your rights depend on your utility's current filed tariff, your state's rules and your interconnection agreement. Your state commission's consumer affairs branch is the right place to take a delay that has gone beyond explanation.

Questions

What is Permission to Operate?

Your utility’s authorisation to energise and run your solar system. It is a separate approval from your city’s electrical inspection, and it comes after it. In the tariff we read it is defined as the distribution provider’s approval for interconnection, where the distribution provider is the utility rather than any local authority.

How long does PTO take?

There is no national answer because there is no national rule. The one tariff we found that sets a standard gives the utility thirty business days, and only from the point at which it has received all three of a completed interconnection request with payments, a signed interconnection agreement, and evidence of your final electrical inspection clearance. Your own utility’s tariff is the document that answers this for you.

Why does PTO come after the inspection?

Because in the tariff we read the inspection clearance is one of three preconditions the utility must receive before its review period begins. The two approvals are in series rather than in parallel. A passed inspection is an input to the next stage, not the end of the process.

Can I turn my system on before PTO?

You should not. Operating before authorisation is generally a breach of your interconnection terms whatever your hardware allows, and it gives every party you may later need cooperation from a reason to withhold it. If your installer suggests otherwise, get that in writing and ask them to cite the provision that permits it.

What if the utility misses its deadline?

In the tariff we read, it must notify you and the state commission with a reason and an expected completion date. There is no deemed approval, so the application is not granted automatically by the passing of time. What the deadline gives you is a reference point and an obligation the utility owes its regulator, which is a useful thing to be able to cite.

Is interconnection a federal matter?

For a rooftop system, no. FERC stated that it declines to exercise jurisdiction over interconnections of distributed energy resources to distribution facilities in this context, and that such interconnections are governed by applicable state or local law. Federal interconnection procedures are the wrong document to cite for a residential timeline.

Why did my installer say my inverter needed to be a specific certification?

Because certification to the current standard can be a prerequisite in your utility’s tariff rather than a preference. The tariff we read makes certification a prerequisite for inverters installed after a specific date in 2017, and handles equipment certified to different revisions under different sections with different requirements. It is worth confirming the specified equipment matches your utility’s current tariff before installation.

What is an AHJ?

The Authority Having Jurisdiction, meaning whichever local body inspects and signs off your installation, usually a city or county building department. The tariff phrase is "the Governmental Authority having jurisdiction over the Generating Facility". It is the body that issues the inspection clearance your utility then needs before its own clock starts.

Written and audited by

HyreSolar Research

Primary-source research, data analysis and fact checking

We are a research desk, not a sales floor. We read the statute, the tariff, the code section, the federal filing or the manufacturer data sheet ourselves, and we publish the figure with the document it came from and the date we retrieved it. Where a number cannot be traced to a primary source, we publish the shorter page and say what we could not verify. That rule has cost us whole sections, and it is the reason the rest can be trusted.

160: primary sources read and cited
220: figures with a retrieval date
115: federal and state government sources
66: researched pages published

How this desk works

Primary sources only. Statutes from the legislature’s own publishing system, federal data from the agency that collects it, code text from the adopted edition, manufacturer claims from the data sheet. We do not cite an article that cites a source; we go and read the source.
Every figure carries its provenance. A named document and the date we retrieved it, so you can check it and so you know how old it is. Retrieval dates are not decoration: an EIA rate from May is a different fact from an EIA rate from August.
We publish what we could not verify. Every research page carries a section naming the things we tried to establish and could not, and why. A paywalled standard, a state website that refused the request, a manufacturer that publishes no figure at all.
We separate measurement from modelling from our own reasoning, and label which is which on the page. A laboratory measurement, an assumption inside a modelling tool and our own inference are three different kinds of claim and they are never presented as one.
We do not sell solar, and we take no payment for placement, ranking or a favourable mention. Nobody buys a position on this site.

Data as of Utility tariffs and federal orders read on 2 September 2026. Authorship on this site is organisational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold. Our editorial policy sets out how we source, date and correct what we publish.

Sources & retrieval dates

PG&E Electric Rule No. 21 (Advice 7692-E) — Effective 29 August 2025. Source for the definition of Permission to Operate, the three preconditions, the thirty-business-day processing standard, the obligation to notify the applicant and the CPUC on a miss, the absence of any deemed approval, the implementation of IEEE 1547-2018 default settings, and the rule that certification is a prerequisite for inverters installed after 8 September 2017. A tariff filed with and approved by the California Public Utilities Commission; not a statute and not applicable to other utilities. Retrieved 2 September 2026.
FERC Order No. 2222, 85 FR 67094 — Published 21 October 2020. Source for the Commission declining jurisdiction over interconnections of distributed energy resources to distribution facilities (paragraph 90) and for the statement that such interconnections "are governed by the applicable state or local law" under the first use test (paragraph 92). Retrieved 2 September 2026.
IEEE 1547-2018 and IEEE 1547a-2020 — Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces, published 6 April 2018, with a 2020 amendment revising allowable trip clearing time settings. Source for the edition, title and scope. Retrieved 2 September 2026.
CPUC, Electric Rule 21 — Source for the description of Rule 21 as a tariff describing interconnection, operating and metering requirements for generation facilities connecting to an investor-owned utility’s system. Retrieved 2 September 2026.
Washington Administrative Code 296-46B-010 — Source for the demonstration that the electrical code is a model adopted state by state and by edition: Washington adopts NFPA 70-2023 by reference, with NFPA 70-2026 already scheduled to replace it effective 31 December 2026, and applies the edition in force when the permit issues. Retrieved 2 September 2026.

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