Drawing Solar PV on a Situation Plan: Modules, Inverter and Cable Routes

On the situation plan you draw where the fixed parts of the PV system actually are: module fields, inverter, fixed isolators, the board with the PV way and the cable routes in between. AREI 3.1.2.3 a requires the situation plan to show the location of the sources – explicitly solar panel, inverter and battery – that appear on the single-line diagram. The single-line diagram explains the electrical chain; the situation plan makes it findable on site. For maintenance, alteration or inspection, a reader needs to see which roof face holds the modules, where the inverter is mounted and how the installation reaches the board.

The situation plan is neither a roof-structure design nor a duplicate DC schematic. It complements the single-line diagram without repeating all of its electrical detail.

Shared example job: DB1, INV1, S1 and S2

The fictional job in the PV documentation guide uses DB1 for the main board, INV1 in the technical room and S1/S2 for the strings on the east and west roofs. These are editorial references, not an exported example project. For your job, use the actual designations.

An unsurveyed cable segment goes on the work list as an open item instead of getting a falsely precise route. Before handover, the contractor matches these references on the installation and both drawings. The installation planning guide explains assignment and the derived diagram; the on-site spatial survey comes from the professional.

Start from an as-built survey

Work from a recognisable plan with storeys, rooms, access points and important external areas. For a roof array, a roof plan or an extra elevation helps. Verify on site:

• actual module fields and orientation;
• central inverters or microinverters;
• fixed DC and AC isolation points where installed;
• main or sub-distribution board receiving the PV connection;
• fixed penetrations and important cable routes;
• meter cabinet where needed to explain the connection;
• battery, backup switching or another source included in the system.

Do not copy the quotation drawing without checking it. Module layout, inverter location and cable route frequently change during installation.

What to show on the roof

Make the module field unambiguous. Depending on scale, show:

• individual modules or clearly bounded module groups;
• the relevant roof pitch, outbuilding, façade or ground area;
• string references where they connect the plan to the single-line diagram;
• fixed DC combiner or switching boxes;
• useful roof edges, access points or fire compartments where they explain electrical location.

Every connector beneath every module does not belong on the situation plan. String arrangement, polarity, conductor data and the protection chain sit on the PV single-line diagram. You use identical string and equipment identifiers on both documents.

Locate the inverter precisely

Mark the actual mounting position and distinguish where relevant:

• central string inverter;
• multiple inverters;
• microinverters at the modules;
• hybrid inverter and separate battery;
• associated fixed isolation or switching devices.

A label saying only “garage” is often too vague in a large space. Put the symbol at the correct wall or technical zone. For outdoor equipment, identify the façade clearly.

Draw useful cable routes

A serviceable plan shows how the fixed route runs from module field to inverter and onward to the board. Above all, include building penetrations, risers, ducts and changes of level that will later be concealed.

You distinguish DC and AC routes by line style or text, not colour alone, so that a black-and-white print stays readable:

PV-DC  ─ ─ ─  DC route from the module field
PV-AC  ─────  AC route to the distribution board
DATA   ·····  fixed metering or communication route

Define each line in the legend. It does not state cable type or installation method; those data stay with the circuit on the single-line diagram.

Symbols and project legend

Table 2.23 of AREI Book 1 V06 is explicitly a non-exhaustive symbol list. Where it has no suitable symbol, 3.1.2.1 a allows any other clearly identifiable symbol defined in the legend of the single-line diagrams and situation plans. Ensure:

• sufficient size in the final PDF;
• different form or text for inverter and battery;
• stable references across pages;
• meaning that does not rely only on colour;
• clear distinction between electrical equipment and building objects.

The AREI electrical-symbol overview explains the legend rule in more detail.

Share references with the single-line diagram

AREI 3.1.2.1 a sets one referencing logic for both plans: on the situation plan, items carry the letter of their circuit and the sequence number from the single-line diagram. The inverter AC branch therefore carries the same identifier on the situation plan and the single-line diagram. String and equipment references used on both also agree.

Check in both directions:

1. Every fixed PV item on the situation plan can be found on the single-line diagram or in its legend.
2. Every spatially relevant PV component on the single-line diagram has a discoverable position.
3. Board and storey names match.
4. Address, date and document revision are the same.

See single-line diagram versus situation plan for their separate roles.

Special configurations

Microinverters

For many identical units, a grouped symbol with quantity, type and related modules is clearer than overlapping marks. The electrical parallel connection stays visible on the single-line diagram.

Home battery

Locate the battery, inverter, fixed isolation and any backup board. A battery is not a PV module and gets its own symbol. Location constraints come from design and manufacturer information; the plan records the installed position.

Outbuilding or ground array

Show the route between buildings, the entry point and the sub-boards involved. An arrow marked “to house” without a precise destination makes every later job harder.

Existing installation

AREI 8.2.2 point 7 allows existing household PV installations up to 10 kVA that fall under that existing-installation regime to rely on a written description, possibly supplemented by photographs, instead of a situation plan under 3.1.2.3 a. The derogation does not apply to new construction or significant alterations; there, you draw an up-to-date situation plan. Whether a particular existing installation qualifies is for the professional to establish.

Dossier and photographs

Photographs help document concealed routes, roofs and equipment labels; the structured electrical plans remain the basis. Retain:

• final situation plan and single-line diagram;
• module and inverter data;
• available string and measurement records;
• manuals and equipment declarations;
• reports from the approved inspection body;
• later changes under a new revision.

The owner keeps the dossier available and has it updated after alterations. For PV up to 10 kVA, 7.112.2 explicitly requires the items listed in Section 9.1.2 to be available for consultation by anyone concerned.

Pre-export check

• Are module fields, inverters and fixed auxiliary devices at their actual locations?
• Are DC and AC routes distinguishable and explained in the legend?
• Do circuit, string and board references match the single-line diagram?
• Are symbols and labels legible at the intended print size?
• Does the plan show as-built conditions rather than the original offer?
• Do both plans carry the same address, date and revision?

Organising a multi-sheet plan

If the roof, technical room and boards cannot fit legibly on one sheet, use named views. An overview connects the building, roof areas and distribution boards, while detail sheets enlarge arrays and equipment zones. Number every sheet and use explicit continuation notes such as “PV-DC continues on sheet LP02”.

Keep enough orientation on each view: storey, room, north arrow or recognisable façade. One equipment identifier appears at several positions only if several devices really exist. A reference table links symbol, equipment ID, circuit and sheet. A large installation stays traceable without shrinking labels or drawing long ambiguous lines across the page.

Worked case: two roof faces and one inverter in a plant room

A house has modules on east- and west-facing roofs, two DC strings and one inverter in the plant room. Show two identified array areas rather than one icon at the centre of the roof. State which string reference belongs to each face and where its DC conductors enter the building. A shared route to the plant room is drawn only where the installed cables really share it.

Give the inverter a stable equipment reference and its actual wall position. If DC isolation, surge protection or other fixed equipment is external, locate it too and link its identifier to the single-line diagram. Integrated functions stay with the equipment record; you do not invent separate boxes. The AC route ends at the correct board and circuit; a line aimed merely at the nearest room adds no traceability.

Check the orientation of each roof detail. Roof face, eaves, ridge, north direction and recognisable building edges let a person find the array and entry point on site. The situation plan is not a mounting drawing showing every hook, but it shows every difference that matters for electrical assignment, safe work and later fault finding.

Survey concealed or inaccessible routes honestly

Where an existing installation hides a route, you do not draw a geometrically precise one either. Mark the section as concealed or derived from retained documentation and keep the source of that information. Photographs of entries, labels, penetrations and the plant room narrow the uncertainty. A dashed line has that meaning only when the legend defines it.

Separate three evidence states: observed on site, supported by reliable technical records and still unresolved. Open items belong on the work list, not as confident lines on the final drawing. Before inspection, the responsible professional decides whether more surveying or access is required.

Carry roof alterations through the documents

After replacing modules, extending an array or changing an inverter, you review more than the roof outline. Update array and string identifiers, cable route, entry point, equipment location, DC and AC references and supporting technical records. Even where modules are replaced within an existing string, record the actual installed quantity and rating – exactly the data that 7.112.4 also lists for the inspection report. If strings are rearranged, the single-line diagram and situation plan carry the same new state.

Archive the superseded edition separately with its date. That makes clear whether a photograph or inspection report concerns the old or the current arrangement. An inverter cloud portal provides production data; the spatial survey and plan revision remain your job.

Check the final edition at the intended print size. A new array does not cover existing references, and a new cable route does not look like a building edge. Move detail frames deliberately, update the sheet index and check every continuation note. An extended roof installation then stays understandable on site without zooming or access to the editing file.

The official FPS Economy page on domestic electrical inspections explicitly includes energy sources on both diagrams and PV technical documentation in the dossier. The required detail follows the installation and the current official Book 1 V06, not a generic roof template.

Creating the plan in PlanElec

With PlanElec, you place PV components on the situation plan, record their electrical structure on the single-line diagram and export both as PDFs. A module symbol stands for a complete string and is assigned to exactly one string of the linked inverter; the self-check reports missing, duplicate and invalid string links. Both plans use the same project data, so references do not drift apart. The roles are clear: the AREI/RGIE self-check shows you findings within the supported rules, the comparison with the installation happens on site, and the official inspection is done by the approved inspection body.

Sources and reviewed version

The basis is the official AREI/RGIE Book 1 publication: Table 2.23, Part 3 (3.1.2.1 and 3.1.2.3), Chapter 7.112, the narrow existing-installation derogation in Part 8 (8.2.2 point 7) and the dossier requirements in Part 9. Reviewed against V06 on 5 October 2026.