What is hosting capacity?

The amount of distributed generation a section of distribution network can absorb before the utility needs to study the interconnection more closely, rather than approving it on a fast track. It is set by voltage, thermal and protection considerations on that specific line section, and it changes as more generation connects.

What is the 15% rule?

A fast-track interconnection screen: generation on the line section, including the proposed system, must not exceed 15% of the line section annual peak load. It appears in the IREC model procedures and in PG&E and Eversource handbooks. Failing it moves an application to supplemental review, not rejection.

Will hosting capacity stop my home solar project?

Probably not. A 7.6 kW system uses 3% of the remaining capacity in our base case. Hosting capacity binds more easily on large commercial and community projects. The exception is a small feeder already carrying a lot of generation, such as one on a rural cooperative.

Where do I find my utility’s hosting capacity map?

On the utility’s own website, under interconnection or distributed generation, sometimes called an integration capacity analysis. Utilities in California, New York and Massachusetts publish one; others may not. Where none exists, your installer can request the line section figures the 15% screen needs.

Why does this tool not just look up my address?

There is no national hosting capacity dataset to look it up in. Each ICA map is published by its utility on its own schedule. A table assembled from them would be stale within months, and a stale figure could tell you a project is blocked when it is not, or show headroom already taken.

My project failed the screen. What now?

Ask three questions of your installer: what supplemental review involves in this territory, what it costs and adds to the timeline, and whether an export limit or a power control system would bring the project back inside the screen without a study. Ask about the third even if nobody offers it.

Would a smaller system pass?

Probably not, at residential scale. Moving from 11 kW to 7.6 kW changed the feeder aggregate in our scenarios from 531 kW to 528 kW against a 600 kW limit. If the feeder is at its screen, shrinking your array will not change the outcome. Export limiting is the stronger lever.

Does a battery affect hosting capacity?

It can, in both directions. A battery is an added source and may count in the aggregate, but one set to limit or shift export can also reduce a system’s impact and is sometimes the remedy when a screen fails. Treatment is territory-specific; this tool does not model it.

The map shows headroom but the 15% screen fails. Which is right?

Both, because they measure different things. A published hosting capacity figure reflects the utility’s technical analysis of that line section; the 15% screen is a coarse procedural test against peak load. An application can clear one and not the other, so the tool reports them separately.

HyreSolar tools

Can your feeder take another solar system?

Screens a proposed system against the remaining hosting capacity on your utility’s map and the 15% fast-track screen. Bring your own utility’s figures.

Checked September 3, 2026. Data as of September 5, 2026. HyreSolar sells and installs nothing.

A home-sized system uses a small share of a feeder’s remaining hosting capacity, so the feeder’s own figures decide the answer. A 7.6 kW system on a feeder with 250 kW remaining uses 3% of it.

Under the 15% screen, a feeder with a 4 MW peak load allows 600 kW of generation, and 520 kW plus 7.6 kW clears it.

Screen your feeder

Two independent paths: fill whichever your utility gives you figures for. Nothing is stored or emailed.

Example values The filled-in numbers are an example, not your home. Type over them with your own.

— Screening verdict

— What to do

— Against the map figure

— Against the 15% screen

— Feeder headroom

— Share of remaining capacity

How this result was worked out

Working it out from the numbers above.

One screen among several. Failing it means further study, not refusal.

HyreSolar publishes no hosting capacity data; the figures come from your own utility’s map. We do not sell systems.

How to read a screen result

Failing a screen is not a refusal. It means the application moves from fast track into supplemental review or a study, which costs time and sometimes money and can end in approval, sometimes with a condition attached. A screen failure is not a rejection.

Your system size is not what decides it here. Look at the base case: going from 7.6 kW to 11 kW moves the feeder aggregate from 528 kW to 531 kW against a 600 kW limit.

What decides the answer is how much generation is already on your line section, which is a fact about your neighbors, not about your roof.

If you cannot get a utility figure, the tool says so rather than guessing. There is no national hosting capacity dataset we can retrieve, and inventing one would let you conclude a project is blocked when it is not. "Cannot screen" is an honest output.

Likely passes the screen: Nothing to do: hosting capacity is unlikely to feature in your interconnection.
Likely supplemental review: Ask your installer what supplemental review means in your territory: what it costs, what it adds to the timeline, and whether an export limit or a smaller inverter would clear the screen instead.
Cannot screen without a utility figure: Find your utility’s integration capacity analysis map, or ask your installer for the line section peak load they used. Utilities in California, New York and Massachusetts publish maps.

Where to find each number

Where each input comes from, so nothing is a guess.

1. Enter the inverter AC output

Not the DC array size. Interconnection screens act on what the system can push into the network, which is set by the inverter.

Where to find it: The equipment page of your proposal. A 12 kW array can carry a 9.6 kW inverter, and 9.6 is the figure that matters here.

2. Find your utility’s hosting capacity map, if it has one

Called an integration capacity analysis, a hosting capacity map, or a DER map. It shows remaining capacity by line section, as a color-coded map you can search by address.

Where to find it: Your utility’s website, under interconnection or distributed generation. California, New York and Massachusetts utilities publish these; others may not.

3. Enter the remaining capacity for your line section

In kilowatts. Note the map’s vintage: these are refreshed on utility schedules and a figure can be a year old.

Where to find it: The map, once you have located your address. If it reports megawatts, multiply by 1,000.

4. Or use the 15% screen instead

If no map exists, the fast-track screen still applies: aggregate generation including yours must not exceed 15% of line section annual peak load. You need the peak load and the existing generation.

Where to find it: Your installer can request these, and they appear in interconnection application correspondence. This is a fair question to ask before you sign.

5. Read the headroom, not just the verdict

The headroom figure tells you how close the feeder is to its screen. Five kilowatts of headroom means the next neighbor to apply may not clear it.

Where to find it: The output. It is the number that tells you whether timing matters.

6. If it fails, ask about the alternatives before accepting a study

An export limit, a smaller inverter, or a power control system can sometimes bring a project back inside a screen without a study at all.

Where to find it: Your installer. These options are territory-specific; ask which apply.

How the calculator works it out

1
Take the ICA path if you have a map figure
Compare the proposed inverter output against the remaining hosting capacity published for your line section.
2
Take the 15% path if you have line section figures
Aggregate generation, including the proposed system, against 15% of line section annual peak load.
3
Report both independently
They can disagree. A feeder can have published headroom and still fail the fast-track screen, or the reverse, because they measure different things.
4
Say plainly when neither can be run
No utility figure means no screen. The tool does not substitute an assumption.

The formula, in full. ICA path: proposed inverter kW ≤ remaining hosting capacity kW. Fast-track path: (existing aggregate generation kW + proposed kW) ≤ 0.15 × line section annual peak load kW. Headroom = 0.15 × peak load − existing generation.

A worked example, start to finish

A 7.6 kW residential system on a suburban feeder with a 4 MW annual peak load, already carrying 520 kW of distributed generation, in a territory whose utility publishes an integration capacity map showing 250 kW of remaining capacity on that line section.

Step	Value
Proposed inverter output	7.6 kW AC
Remaining hosting capacity from the map	250 kW
Share of remaining capacity used	3%
Line section annual peak load	4,000 kW
15% screen limit	600 kW
Existing generation on the line section	520 kW
Aggregate with the proposed system	528 kW
Result	Passes both, 80 kW of headroom left

Both paths clear comfortably. The instructive figure is the 3%: this house uses three percent of the remaining capacity on its line section.

Roughly thirty more houses of this size could do the same before the map figure is used up.

That is why a single home can pass easily and a later one can hit the limit, which is what the headroom output is for.

How the answer moves

The same 7.6 kW system against different feeder conditions. Every row is computed by the tool on this page.

Situation	Verdict	ICA path	15% fast-track screen
Base case7.6 kW, 250 kW map headroom, 4 MW feeder, 520 kW existing	Likely passes	fits: 7.6 into 250 kW	passes: 528 kW against 600 kW
Map shows only 5 kW left on the line section	Likely supplemental review	does not fit: 7.6 into 5 kW	passes: 528 kW against 600 kW
Feeder generation already at 595 kW	Likely supplemental review	fits: 7.6 into 250 kW	fails: 603 kW against 600 kW
Feeder generation already at 600 kW	Likely supplemental review	fits: 7.6 into 250 kW	fails: 608 kW against 600 kW
11 kW system instead of 7.6	Likely passes	fits: 11 into 250 kW	passes: 531 kW against 600 kW
No utility figures available	Cannot screen	no map figure entered	no line section figures entered

Rows two and three are the point of running both paths. They disagree, and neither is wrong: a published map figure and the fast-track screen measure different things, so a feeder can have map headroom and still fail the 15% test.

Note also that the 11 kW row barely moves the aggregate: going from 7.6 kW to 11 kW shifts a 528 kW total to 531 kW. In these scenarios your system size is not what decides it.

What moves this number most

Ranked, largest first. A proposal can change any of these without saying anything untrue, so check these inputs first.

1. How much generation is already on your line section

The largest factor in these scenarios, and outside your control. It is a fact about how many neighbors already have solar, not about your house or your design.

2. Whether your utility publishes a map at all

Utilities in California, New York and Massachusetts do; others may not. Where no map exists the 15% screen still applies, but you have to ask for the inputs rather than look them up.

3. The line section peak load

Sets the 15% ceiling. A larger, busier feeder absorbs far more generation before any screen binds, which is why a large feeder is unlikely to constrain a single house.

4. Your inverter output, weakly

Included for completeness, and included precisely to show how little it matters at residential scale. A 3.4 kW difference in system size moved the feeder aggregate by 0.5% in our scenarios.

5. Map vintage

ICA maps are refreshed on utility schedules, not continuously. A figure can be months old and the queue moves in between, which is why headroom close to zero should be treated as already gone.

6. What is deliberately absent

Voltage rise, thermal limits, protection coordination, reverse power flow at the substation and every other technical screen an interconnection review applies. Hosting capacity is one gate of many, and passing it is not approval.

Common mistakes with this calculation

Reading a screen failure as a refusal
It means further study, not rejection. Supplemental review can end in approval, sometimes with a condition such as an export limit. Ask what the study costs and what it adds to the timeline before assuming the project is dead.
Assuming a smaller system fixes it
At residential scale it may not. Our scenarios move a 528 kW aggregate to 531 kW across a 3.4 kW change in system size. If a feeder is at its screen, your house is not what put it there and shrinking your array will not pull it back.
Trusting a map figure without checking its vintage
These are periodic snapshots. Projects enter the queue between refreshes, so a map showing 5 kW of headroom is best read as showing none.
Using the DC array size
Screens act on inverter AC output. A 12 kW array on a 9.6 kW inverter is a 9.6 kW question, and using 12 will overstate your impact.
Treating a pass as an interconnection approval
Hosting capacity is one screen among several. Voltage, protection and thermal screens are applied separately and any of them can send an application to study.
Not asking about export limiting
In some territories a system that fails a hosting capacity screen can be brought back inside it by limiting export rather than by shrinking generation, which preserves your self-consumption. It is worth asking about before accepting a study.

What this calculator leaves out

The result is a planning estimate. A real proposal accounts for these; this page does not.

HyreSolar publishes no hosting capacity data.
ICA maps are produced per utility on their own refresh schedules and there is no retrievable national table.
A screen result is not an interconnection decision.
Failing a screen means further study, not refusal.
Covers the hosting capacity and 15% fast-track screens only.
Voltage rise, thermal, protection and reverse-power screens are applied separately.
The 15% screen appears in the IREC model procedures and several utility handbooks but is not universal, and some states have replaced or supplemented it with hosting-capacity-based screens.
Map figures are periodic snapshots.
Queue positions taken between refreshes are not reflected.
Assumes a radial distribution circuit.
Other circuit designs exist.

The research behind these numbers

How solar interconnection worksWhere hosting capacity sits among the screens an application passes through.Read the research Interconnection timeline trackerIf a screen sends you to supplemental review, this is where the extra weeks show up.Read the research Service panel checkThe constraint inside your own house, checked from the ratings on your panel label.Read the research Solar on a rural cooperativeSmaller feeders, lower peak loads, and the setting where a 15% screen is most likely to bind on a house.Read the research If net metering endsHigh DER penetration drives both hosting capacity limits and tariff change, and the two can arrive together.Read the research

Questions this calculator answers

What is hosting capacity?: The amount of distributed generation a section of distribution network can absorb before the utility needs to study the interconnection more closely, rather than approving it on a fast track. It is set by voltage, thermal and protection considerations on that specific line section, and it changes as more generation connects.
What is the 15% rule?: A fast-track interconnection screen: generation on the line section, including the proposed system, must not exceed 15% of the line section annual peak load. It appears in the IREC model procedures and in PG&E and Eversource handbooks. Failing it moves an application to supplemental review, not rejection.
Will hosting capacity stop my home solar project?: Probably not. A 7.6 kW system uses 3% of the remaining capacity in our base case. Hosting capacity binds more easily on large commercial and community projects. The exception is a small feeder already carrying a lot of generation, such as one on a rural cooperative.
Where do I find my utility’s hosting capacity map?: On the utility’s own website, under interconnection or distributed generation, sometimes called an integration capacity analysis. Utilities in California, New York and Massachusetts publish one; others may not. Where none exists, your installer can request the line section figures the 15% screen needs.
Why does this tool not just look up my address?: There is no national hosting capacity dataset to look it up in. Each ICA map is published by its utility on its own schedule. A table assembled from them would be stale within months, and a stale figure could tell you a project is blocked when it is not, or show headroom already taken.
My project failed the screen. What now?: Ask three questions of your installer: what supplemental review involves in this territory, what it costs and adds to the timeline, and whether an export limit or a power control system would bring the project back inside the screen without a study. Ask about the third even if nobody offers it.
Would a smaller system pass?: Probably not, at residential scale. Moving from 11 kW to 7.6 kW changed the feeder aggregate in our scenarios from 531 kW to 528 kW against a 600 kW limit. If the feeder is at its screen, shrinking your array will not change the outcome. Export limiting is the stronger lever.
Does a battery affect hosting capacity?: It can, in both directions. A battery is an added source and may count in the aggregate, but one set to limit or shift export can also reduce a system’s impact and is sometimes the remedy when a screen fails. Treatment is territory-specific; this tool does not model it.
The map shows headroom but the 15% screen fails. Which is right?: Both, because they measure different things. A published hosting capacity figure reflects the utility’s technical analysis of that line section; the 15% screen is a coarse procedural test against peak load. An application can clear one and not the other, so the tool reports them separately.

Sources and methodology

Figures dated September 5, 2026. Last reviewed September 3, 2026 by the HyreSolar research desk, which writes and checks every tool on this site.

Model Interconnection Procedures, 2023 edition (Interstate Renewable Energy Council (IREC), retrieved September 5, 2026). Source for the 15% of line section annual peak load fast-track screen and for the definition of a line section.
Distribution Interconnection Handbook (Pacific Gas and Electric Company, retrieved September 5, 2026). An example of the 15% screen as applied in a utility handbook, and of the supplemental review path when a screen is not met.
Guidelines for Generator Interconnection: Fast Track (Eversource Energy / The United Illuminating Company, Docket 17-12-03, retrieved September 5, 2026). A second independent statement of the same screen, used to confirm the rule is not utility-specific.
Rule 21: Generating Facility Interconnection (California Public Utilities Commission, retrieved September 5, 2026). The state rule under which California utilities publish integration capacity analysis maps. Named as where to look, not used as a national benchmark.

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