The 65 design checks every solar plan set should pass.

Every overcurrent device rating must be in the NEC 240.6(A) standard size table.

Shows up as: Breaker or fuse rating is not a size you can buy

Breakers and fuses only come in specific standard sizes (like shoe sizes). This one is set to a size that isn't actually made, so it needs to round to the nearest real size you can buy.

Verify overcurrent protective device rating matches the conductor ampacity it protects.

Shows up as: Breaker is too large for the conductor it protects

A breaker is the safety valve for a wire: it has to trip before the wire overheats. Here the breaker is too big for the wire it's protecting, which means the wire could get dangerously hot before the breaker ever shuts off.

Every conductor needs an OCPD at the source unless it qualifies for a tap-rule exception.

Shows up as: Conductor has no overcurrent device at its source

Every wire needs a breaker or fuse at the point where its power comes from. This wire doesn't have one, so there's nothing to shut it off if it shorts out.

Every power-producing circuit (PV branch, inverter output, battery output) must continue to an overcurrent device or a point of interconnection. A circuit that dead-ends inside a junction box or other pass-through carries no protection and connects to nothing.

One of your power-producing circuits stops partway: it runs into a junction box (or similar splice point) and nothing carries it the rest of the way. That circuit has no breaker and no connection to the rest of the system, so it produces nothing and would fail inspection. Run the missing wire from that box to its own breaker, or delete the circuit if it isn't really there.

Verify upstream OCPDs are sized at or above downstream OCPDs (selective coordination).

Breakers should get smaller as you move away from the power source, like branches off a tree trunk. Here a breaker downstream is bigger than the one feeding it, which can let the wrong breaker trip first during a fault.

Branch + feeder voltage drop within recommended limits (≤3% branch, ≤5% total).

Shows up as: Wire run loses too much voltage over its length

Electricity loses a little 'push' over long wire runs, like water pressure dropping over a long hose. This run loses too much, which can make equipment underperform: usually fixed by using a thicker wire.

Grid-tied inverter output conductors: voltage rise ≤2% target / ≤5% over-voltage-trip ceiling (IEEE 1547 + ANSI C84.1 trip window).

A solar inverter PUSHES power out to the grid, so its wire to the grid gains a little voltage instead of losing it (the opposite of a normal appliance). If it gains too much, the inverter sees the voltage as too high and shuts itself off on the sunniest part of the day: losing production. The fix is a thicker wire or a shorter run.

Equipment Grounding Conductor sized per NEC 250.122 table based on upstream OCPD rating.

Shows up as: Equipment grounding conductor is undersized

The ground wire is the safety path that carries fault current away so a metal enclosure never becomes live. This ground wire is too small for the breaker protecting it and needs to be sized up.

Load-side wires must include EGC; supply-side wires to a bonded source must not.

Ground wires belong on some runs and not others depending on which side of the main service they're on. This run has the ground wire handled the wrong way for its location.

Grounding Electrode Conductor sized per NEC 250.66 based on service-entrance ungrounded conductor size.

The main grounding wire that ties your whole system to the earth (via a ground rod or water pipe) is sized off the service conductors. This one doesn't match and needs adjusting.

A GES must be connected to the service-entrance equipment.

The system has to be physically tied to the earth through a grounding electrode (a ground rod, the water pipe, or rebar in the foundation). No grounding electrode is connected to the service yet.

GEC must land at the service disconnect (not a downstream block).

The main grounding connection has to land at the service disconnect, the first shutoff after the meter, not somewhere deeper in the system. It's currently attached to the wrong spot.

The first OCPD-providing block downstream of the meter MUST carry both the N-G bond and the GES. Downstream blocks must NOT.

Exactly one piece of equipment, the first shutoff after the meter, is where the neutral and ground get bonded together and the earth connection lands. That bonding is either missing here or happening at the wrong box.

A 2-wire DC circuit (PV string, battery interconnect) carries exactly two current-carrying conductors, positive and negative, plus EGC. A neutral or extra phase conductor on a DC wire misprints the conductor schedule's pull count.

DC wiring, like the run from your solar panels to the inverter, or a battery's DC feed, uses exactly two wires (a positive and a negative) plus a ground. If the plan lists a neutral or a third current-carrying wire on a DC run, the installer would be told to pull wire that doesn't belong in that circuit. This check catches the mislabel before it prints on your plans.

A junction box or disconnect cannot change a circuit's phase-conductor count: the wire leaving it must match the wire entering it. Devices carrying the neutral-ground bond are exempt (the service point, where the conductor set follows service rules per NEC 250.24(C)). Neutral correctness is covered separately by the Neutral Continuity trace.

A junction box or disconnect just passes wires through, it can't create a new wire out of nothing. If the plan shows a circuit entering a box with two hot conductors and leaving with three, one side of the plan is wrong, and this check flags it before an installer or inspector has to puzzle over it. The one place the rules change is the service disconnect that carries the neutral-to-ground bond, the conductor set legitimately changes there, so that device is exempt.

When a new feedthrough panel is inserted at a solar feeder tap, its main breaker over the pre-existing downstream conductor is a contested NEC 705.12(A)(2)(b) reading. This check flags a main above the downstream conductor's ampacity and presents the uncontested resolution: drop the main to the conductor (e.g. 125A over #1 Cu), replace the conductor, or keep the full rating only where the AHJ accepts the segment reading.

When solar taps the feeder between your meter-main and your loads panel, one fix is inserting a new panel with its own breaker at the tap. If that breaker is rated higher than the older wire continuing downstream can carry, inspectors read the rules two different ways: and one of those ways fails your inspection. The safe answer nobody disputes: use a breaker sized to the existing wire (typically 125A over the common #1 copper), and this check tells you exactly that number.

The grounded conductor must run continuously from the service to every device that terminates it: panels serving 120V circuits, combiners with monitoring inside, gateways, most inverters. This check traces the whole diagram: a wire on that path missing its neutral is an error; a neutral that serves nothing beyond its wire is an informational note.

The neutral wire has one job: run from the utility service to every device that actually uses it, your breaker panel's 120V circuits, the monitoring unit inside a solar combiner, the backup gateway. This check traces that path across the whole diagram, both ways. A wire on the path missing its neutral means the installer pulls too few conductors and the equipment at the end won't work. A neutral drawn where nothing uses it means the plan calls for a conductor with no landing point, and on a factory microinverter trunk cable, a conductor the cable physically doesn't have.

Maximum DC voltage on a PV string within the inverter's maximum DC input voltage (NEC 690.7).

Solar panels wired in a row add up their voltage, and on a cold sunny day that voltage spikes. This string's voltage can climb past what the inverter can safely handle: usually fixed by putting fewer panels in the string.

Panel count per string must keep Voc (cold) ≤ inverter max and Vmp (hot) ≥ inverter MPPT minimum.

A solar string needs enough panels to start the inverter on a hot day, but not so many that it over-volts on a cold day. This string is outside that safe window and the panel count needs adjusting.

Per-MPPT current does not exceed the inverter's rated MPPT input current.

Each input on the inverter can only take so much current. This input is being fed more than it's rated for, which means some of the solar production would be clipped or the input stressed.

Panel count per AC branch must satisfy NEC 705.13 / 690.8 continuous-current limit AND the microinverter manufacturer's max_units_per_branch[breakerSize] spec table.

Microinverters chain together on a shared circuit, and there's a limit to how many fit on one branch before the wire is overloaded. This branch has too many panels on it and needs to be split.

Every solar string is assigned to a valid MPPT on its inverter (not orphaned or over-stuffed).

Each solar string has to be assigned to an actual input on the inverter. One of these strings isn't assigned to a valid input, so it's effectively floating.

A meter collar installs in the meter socket the utility owns, and not every utility permits one. The design is checked against that utility's recorded policy, with a per-project override for a job the utility approved directly.

A meter collar is a ring that goes into the utility's own meter socket, behind their meter. Because it is their socket and their meter, the utility decides whether one is allowed at all, and the answer is different from territory to territory. Installing one where it is not permitted is a rejected interconnection application, not a code violation, so it is worth settling before the plans go out rather than after.

Supply-side interconnections meet NEC 705.11 conductor sizing + service disconnect requirements.

When solar taps in ahead of the main breaker, special conductor and disconnect rules apply. This supply-side connection doesn't meet one of those requirements yet.

Equipment connected on the supply side of the service (supply-side tap / direct meter connection) must be listed suitable for use as service equipment (SUSE).

Equipment wired in ahead of the main breaker (like a supply-side tap disconnect, or a panel fed straight from the meter) has to be built and labeled for that job: 'suitable for use as service equipment.' This one isn't marked as such yet: confirm the label on the real equipment and flip the Service Rated toggle, or connect it after the main breaker instead.

Unprotected tap conductors on a supply-side interconnection respect NEC §705.11(C). Threshold depends on project scale: residential = 10 ft inside building, commercial = 16.5 ft (or 71 ft with cable limiters). Wires already sized to their downstream OCPD are skipped: they satisfy 705.11(C)(1)(b). The ceiling is an INSIDE-building limit: a conductor whose tap location is declared Outside (or Considered outside per §230.6) is exempt, and the §230.6 case gets an info note since that section is written for service conductors.

When you tap solar in ahead of the main breaker, the unprotected stretch of wire before its disconnect has a strict length limit INSIDE the building. This run is too long for where it's installed: move the disconnect closer to the tap, or, if the wire actually runs outdoors, mark its tap location as outside in the conductor schedule and the limit no longer applies.

Connected blocks share compatible voltage + phase (no single-phase wired to three-phase, no 240V to 480V).

Two pieces of connected equipment expect different voltages or phases (like plugging a 120V device into a 240V outlet). They can't be wired together as-is.

Breaker pole count matches the phase configuration (1P for 120V, 2P for 240V split, 3P for 208/480V wye/delta).

A breaker needs the right number of 'poles' for the voltage it's switching: single-pole for 120V, two-pole for 240V, three-pole for three-phase. This breaker's pole count doesn't match its circuit.

120% rule, sum rule, feed-through tap, and derate enforcement for load-side solar interconnections.

There's a limit to how much solar and battery power you can backfeed into a panel before its busbar is overloaded (the '120% rule'). This design exceeds that limit: options are a bigger panel, a smaller main breaker, or a Power Control System.

PCS-controlled installations: combined source current must not exceed declared PCS limit, and a 705.13-listed host device must be present.

A Power Control System is a smart device that actively limits how much combined power hits the busbar. Either the limit is set too high for the panel, or the listed device that's supposed to enforce it is missing from the design.

Conductors between the PCS host and the protected panel must be sized for PCS setpoint × 1.25 (continuous-load factor), and the OCPD must not exceed the PCS setpoint.

The wires between the Power Control System and the panel it protects have to be sized for the limit the PCS enforces. The wire size or its breaker doesn't line up with that limit here.

A MLO (main-lugs-only) backup panel downstream of a PCS host needs at least one of: (1) external inline OCPD ≤ panel rating, (2) PCS Panel Limits configured for the backup busbar, (3) total island-mode source capacity ≤ panel rating. The gateway internal main breaker does NOT protect the backup panel.

A backup loads panel with no main breaker of its own needs something else to protect it during an outage. Right now nothing is guaranteeing the backup panel's busbar can't be overloaded: the gateway's internal breaker doesn't count.

AC-coupled solar in the Tesla backup circuit ≤ 7.68 kW per Powerwall (10 kW per PW3 with Expansion). Excess must be routed line-side of the Gateway.

Tesla limits how much solar can sit on the backup side of the Gateway per Powerwall. This design has more solar in the backup circuit than the batteries can handle, so some of it has to move to the grid side of the Gateway.

Line-side tap interconnection requires a panel with a line_tap port (main / meter-main) or an external service-entrance tap point. MLO panels have no line_tap port.

A line-side tap needs a panel that actually has a tap point ahead of its main breaker. This panel is main-lugs-only and has no such tap point, so the connection can't land there.

Load-side feeder tap conductors must meet a NEC 240.21(B) length tier: (B)(1) ≤10 ft (ampacity ≥ terminating OCPD), (B)(2) ≤25 ft (ampacity ≥ 1/3 feeder OCPD), or the special >25 ft tiers (B)(4)/(B)(5). With a power source on the feeder, 705.12(A)(3) raises the 1/3 basis to (feeder OCPD + Σ PV OCPDs). Errors on an undersized tap; warns on a >25 ft tap. A tap whose location is declared Outside (or Considered outside per §230.6) skips the length tiers and is checked against the (B)(5) CONDITIONS instead: it must terminate in a single OCPD, rated ≤ the conductor ampacity, at the point of entry; failing either is an error, since without that termination no 240.21(B) tier permits the run. Supply-side line taps (705.11) are excluded. See docs/NEC_240_21B_FEEDER_TAPS.md.

A tap wire connects to a feeder without its own breaker at the tap, so the code limits how long it can be and how small it can be. Short taps (≤10 ft) must carry at least their end breaker; ≤25 ft taps must be at least a third of the feeder's breaker, and because solar adds a second source, that third is figured on the feeder breaker PLUS the solar breaker, so the tap wire often has to be a size or two bigger. A tap that runs OUTSIDE the building has no length limit at all, but only if it ends in one breaker or fuse, no bigger than the wire can carry, right where it enters the building, without that, the outside allowance doesn't exist. This tap doesn't meet its rule, so upsize the wire, add or resize the end breaker, or shorten/relocate the run.

A load-side tap on a feedthrough FEEDER is governed by NEC 705.12(A) (Feeders and Feeder Taps), NOT the busbar 120% rule (B)(2) or busbar feed-through (B)(5). Acceptable when (A)(2)(a) feeder ampacity ≥ primary-source OCPD + 125% PV, OR (A)(2)(b) an OCPD ≤ feeder ampacity at the load-side connection (the downstream panel main). Warns when (b) is not met, MLO downstream panel, or a downstream main exceeding the feeder ampacity (the 310.12(B) 83% main feeder, no longer auto-qualifying post-tap), pointing to (a) as the alternative. A tap does NOT increase the feeder load; this is protection coordination, not overload.

Solar tapped onto the feeder that feeds the downstream panel. The tap doesn't add load to that wire, but it does change which code rule applies: the downstream panel either needs its own main breaker no larger than the feeder can carry, or the feeder has to be big enough for its load plus the solar. Right now neither is confirmed: add a correctly-sized main on the downstream panel, or verify the feeder is large enough.

Detect ambiguous service topologies where multiple panels could be the service disconnect (single-disconnect rule).

The service can only have one main shutoff, but this layout has more than one panel that could be it. The drawing needs to make clear which single panel is the service disconnect.

Every string inverter AC output is wired AND has an OCPD (breaker / fuse / PCS-controlled port) upstream: catches floating inverters when a combiner runs out of breaker slots.

Every inverter's AC output needs both a wire and a breaker/fuse feeding into the system. This inverter is missing one: often because a combiner ran out of breaker slots and left it stranded.

Current into a node equals current out (no source receiving current, no load driving an output, combiner outputs sum branch inputs).

The current going into a junction should equal the current coming out: power can't appear or vanish. The numbers don't balance here, which usually points to a mis-wired or mis-sized connection.

AC source count must not exceed the gateway's physical smart-port slot count. Excess sources require an AC combiner upstream or a sub-distribution panel.

The gateway only has so many physical slots for power sources to plug into, and the design is trying to plug in more than it has. You'd need a combiner panel to merge some sources first, or a bigger gateway.

A breaker installed in a panel should have something landing on it. Empty spaces are not reported: spare capacity is normal hardware. Reports a breaker the system added for a feed that never got wired (auto-fix removes it) and a solar backfeed breaker with no source.

A breaker is drawn in the panel with nothing connected to it. Empty spaces in a panel are fine and are never flagged: this is a breaker the drawing says is installed, either one added automatically for a connection that never happened, or a solar breaker whose source isn't wired to it.

A gateway inverter-input or smart-port breaker, or a combiner branch breaker, drawn as installed with no circuit landing on it. Dashed empty positions are normal spare hardware and are never reported.

The gateway or combiner drawing shows a breaker as installed, but no wire actually lands on it. That tells the inspector hardware exists that the install doesn't have: either wire the circuit or let the drawing mark the position as an empty spare.

An inverter feeding an EG4 GridBOSS inverter input must leave its own LOAD and GEN ports unused: backed-up loads, generators and AC-coupled PV all land on the GridBOSS's own terminals instead.

When an EG4 hybrid inverter is wired into a GridBOSS, the GridBOSS takes over the jobs the inverter's own LOAD and GEN terminals do in a standalone install: EG4's wiring diagrams say those two ports must stay empty. Backed-up loads connect to the GridBOSS backup terminal, a generator to its GEN input, and extra AC solar to a smart port. This flags a design that wired the inverter's LOAD or GEN anyway.

Wire created without a matching conduit-defaults rule: both conduitType + insulationType remain undefined. Pick values manually or extend the rules table.

Every wire run needs a conduit type (the pipe it runs through) and a wire type. The system couldn't auto-pick them for this run, so they need to be chosen manually.

A grid-tied design has a point of connection, meter, service disconnect, main panel or gateway, and a settled interconnection method for the plan set to cite. Off-grid systems are exempt. This is the net under the automatic interconnection resolution: when it cannot resolve, the gap is reported rather than left silent.

Checks that the design actually reaches the utility. A grid-tied system needs somewhere for the power to go, a meter, a service disconnect, a main panel or a gateway, and it needs a settled answer for HOW the solar ties in, because the plan set has to cite that. Off-grid systems skip this. It exists as a backstop: the app now works the connection method out for you at generation, and this reports it when that could not be done rather than leaving you with a drawing that has no point of connection.

Required connection points (utility input, main breaker, etc.) have wires landing on them.

A required connection point (like the utility feed or the main breaker) doesn't have a wire landing on it. Something that needs to be hooked up isn't yet.

Pass-through devices (junction boxes, disconnects) have both input AND output wired.

A pass-through device like a junction box or disconnect has a wire going in but nothing coming out (or vice versa). It needs to be wired through on both sides to actually carry power.

Panel breakers have a downstream wire connected (no orphans drawn but not wired).

A breaker is drawn in the panel but nothing is wired to it. Either wire something to it or remove it so the drawing reflects the real install.

Wires terminate at a known connection point on a block: not free-floating in space.

A wire ends in empty space instead of landing on a real connection point. Both ends of every wire need to attach to actual equipment.

Wire topology is consistent (no upstream loops, no source-into-source connections).

Something is wired in a way that doesn't make electrical sense: like a loop feeding itself, or two power sources wired directly into each other. The wiring path needs to be corrected.

Every piece of equipment is wired into the design: a power source with zero wires is an error.

A piece of equipment sits on the drawing with no wires at all. If it's a solar array, inverter, or battery, that's a real problem: a power source that connects to nothing can't do anything. Wire it in or remove it.

No wire connects two input ports or two output ports: every wire has exactly one sourcing end.

Every wire needs exactly one end supplying power and one end receiving it. This wire connects two 'receiving' terminals (or two 'supplying' terminals): like plugging an extension cord into itself. One end needs to move to the correct terminal.

Panels and meters never land on a gateway's source ports (smart ports / inverter inputs): those are for back-fed sources.

An electrical panel or meter is wired to a spot on the backup gateway that's meant for power sources like inverters and batteries. Panels connect to the gateway's load terminals instead: the wire needs to move to the right terminal.

Solar panels have been set for the design (not left as the template placeholder).

This design started from a template, and the solar panels shown are just the template's example: not your actual panels. Open System Setup → Solar Equipment to pick the real panel model and count before this drawing goes anywhere official.

An AC module has an integrated microinverter: the string must not also carry a separately selected MLPE device.

An AC module already has its microinverter built into the panel, so adding a separate microinverter or optimizer to the same string is counting the same equipment twice. Pick one: the AC module on its own, or ordinary DC panels with the separate device.

A segmented AC combiner reserves each breaker space for one kind of circuit (PV branch, battery, EV charger, load controller), each at its own rating. Every circuit must land on a space meant for it, with a breaker that space accepts.

Newer AC combiners are not a row of identical breaker slots. The maker sets aside particular spaces for particular jobs: a few 20-amp spaces for solar branches, one or two large ones for a battery, one for an EV charger. Each space is wired to a different busbar with its own current rating and its own metering. Putting a battery on a solar space, or fitting a bigger breaker than a space is rated for, builds the equipment in a way it was never listed for, and a plan reviewer will catch it.

The combiner's output to the panel stays within the maximum backfeed breaker and continuous current its listing allows.

The combiner gathers all the solar and battery circuits and sends one feed to your main panel. The maker states the most that feed may carry and the largest breaker it may land on. Going past either asks the shared bus inside the combiner for more current than it was tested for, and fitting a bigger breaker does not make the equipment bigger.

On a battery system that forms the grid during an outage, the manufacturer caps array power as a percentage of battery power, and caps the array the combiner may take at all.

In a battery system that keeps the house running during an outage, the batteries are what create the grid the solar panels sync to. That job has a size limit, so the maker caps how much solar you may pair with a given amount of battery. Once the house's own use is met, power the batteries cannot absorb has nowhere to go. More battery raises the ceiling, and less solar lowers the demand.

Monitoring devices are compatible with the inverters/gateways they monitor.

The monitoring device (the part that reports production to an app) has to be compatible with the inverter or gateway it's watching. This pairing isn't a supported combination.

A design with storage says whether the customer bought whole-home or partial backup. It decides which loads land on the backup panel, how the gateway is sized, and whether a subpanel is needed: so unlike stringing it cannot be left to the installer, and unlike a rating it cannot be assumed. Five code paths used to guess it and nothing checked the result.

A battery can back up your whole house, or just a few circuits you pick. Those are different systems, not different settings: the second one needs a separate panel for the backed-up circuits, and the equipment is sized differently. So the design has to know which one you bought before it can be drawn, and this flags a project where nobody has said.

The drawing actually contains the system the project was set up for: the same NUMBER of panels and battery units, not merely some. A presence-only version of this rule let a 26-panel job ship a 10-panel drawing and a 2-battery job ship one battery, because every other check reads the canvas as the definition of the design: the sheet stays perfectly self-consistent while being the wrong job. Every other check reads the canvas as the definition of the design, so a design that generated without its array passed all of them while the summary table still reported the configured panel count.

Checks that the drawing contains the system you set up. If you told us the job has solar panels, the sheet has to actually show them. This exists because a design can generate with its array missing while the equipment table still lists the panel count from your settings: so the sheet looks finished, and every other check passes, because they all read the drawing rather than comparing it to what you asked for.

Every meter socket has a current rating set. Recipes may defer rating at creation; this check ensures it is resolved before planset signoff.

The meter socket doesn't have an amperage rating set yet. It needs one before the plan set is finalized so the service size is documented.

When a design is rebuilt from an uploaded single line diagram, every value the drawing states (amp ratings, fused or not, busbar size, voltage) is compared against the value the equipment actually ended up with. Reports each one the design does not match, whether the value was never applied, still carries the default, or was built to something different. Values fixed by a specific product you picked, and values the drawing left unreadable, are not reported.

When you upload a drawing and we rebuild it, we keep a record of every value the drawing states, and this compares that record against what the equipment was actually built with. Here they disagree: the drawing might say a fused 40A disconnect where the design ended up with a non-fused one and no rating at all. Nothing is changed for you, because the drawing is the record of what you asked for. Set the value yourself, or fix the drawing if it was read wrong and rebuild.

For a DC battery wired to a hybrid inverter, checks the two things the drawing cannot show: that the stack voltage falls inside the inverter's battery input range (outside it, the inverter refuses the pack and the system never commissions), and whether the battery, not the inverter, is what limits backup power. Backup output is the smaller of the inverter rating and the stack voltage times its discharge current, so a short stack can halve the backup capacity a nameplate implies.

Checks that a stacked battery and the hybrid inverter it feeds actually work together. Two things a drawing can't show you: whether the stack's voltage is inside the range the inverter accepts (if it isn't, the inverter refuses the battery and the system never turns on), and whether the battery is what limits your backup power. Backup is capped by whichever is smaller, the inverter or the battery, so a short stack on a big inverter can give you half the backup you'd expect from the inverter's nameplate: which matters when you're deciding what loads to put on the backup panel.

Wall-mounted equipment on the elevation pages: minimum mounting heights (AFF), manufacturer/NEC working clearances free of obstructions, no physically overlapping enclosures, operating handles within the 6'-7" max reach, and ESS kept 3 ft from doors/windows.

The elevation drawing shows where equipment physically hangs on the wall, and inspectors check it against real-world rules: boxes can't overlap, shutoff handles must be reachable (no higher than 6'-7"), equipment needs its required breathing room, and batteries have to keep their distance from doors and windows. Something on the wall breaks one of those rules: drag it to a compliant spot.