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

PV documentation often focuses on the single-line diagram, where strings, inverter, protection and the distribution-board connection appear. A situation plan has a different purpose: recording the physical location of fixed electrical equipment. For later maintenance, alteration or inspection, a reader should find the module fields, inverter and fixed route back to 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.

Start from an as-built survey

Use a recognisable plan with storeys, rooms, access points and important external areas. A roof plan or elevation may be needed. 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.

The plan does not need every connector beneath every module. String arrangement, polarity, conductor data and electrical protection primarily belong on the PV single-line diagram. 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” may be too vague in a large space. Put the symbol at the correct wall or technical zone. Identify the façade when equipment is outside.

Draw useful cable routes

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

Distinguish DC and AC routes by line style or text, not colour alone. A black-and-white print must remain understandable:

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 remain attached to the circuit on the single-line diagram.

Symbols and project legend

Table 2.23 of AREI Book 1 V06 is non-exhaustive. A project symbol for a module field, inverter or DC isolator may be used when it is unambiguous and defined in the legend. 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

Part 3 of AREI Book 1 V06 links the two plans through circuit references. The inverter AC branch therefore carries the same identifier on the situation plan and single-line diagram. String and equipment references used on both must 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 may be clearer than overlapping marks. The electrical parallel connection remains 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 needs a distinct symbol. Location constraints come from design and manufacturer information; the plan records the installed position.

Outbuilding or ground array

Show the route between buildings, entry point and any sub-board. An arrow marked “to house” without a precise destination is poor evidence for future work.

Existing installation

Part 8 contains a limited derogation for certain existing domestic PV installations up to 10 kVA, allowing a written description possibly supported by photographs. Do not generalise that existing-installation rule to new construction or a significant alteration. Have the particular case classified correctly.

Dossier and photographs

Photographs help document concealed routes, roofs and equipment labels, but do not automatically replace structured electrical plans. Retain:

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

The owner should keep the dossier available and arrange updates after alterations.

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 represent 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 can connect 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 S2”.

Keep enough orientation on each view: storey, room, north arrow or recognisable façade. Do not repeat one equipment identifier at several positions unless several devices really exist. A reference table can link symbol, equipment ID, circuit and sheet. This keeps a large installation traceable without shrinking labels or drawing long ambiguous lines across the page.

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

Consider a house with 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. Draw a shared route to the plant room only where the installed cables really share that route.

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. Keep integrated functions attached to the equipment record rather than inventing 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 should let a person find the array and entry point on site. The position plan is not a mechanical mounting drawing and need not show every hook. It should show differences that matter for electrical assignment, safe work and later fault finding.

Survey concealed or inaccessible routes honestly

Do not invent a geometrically precise path where an existing installation hides it. Mark a section as concealed or derived from retained documentation and keep the source of that information. Photographs of entries, labels, penetrations and the plant room help 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 in a survey task 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, 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, retain the actual installed quantity and rating in the relevant dossier information. If strings are rearranged, the single-line and position plan must share the new state.

Archive the superseded edition separately with its date. This makes clear whether a photograph or inspection report concerns the old or current arrangement. An inverter cloud portal can provide production data, but it is not a spatial survey and does not replace the position-plan revision.

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 current official Book 1 V06, not a generic roof template.

Creating the plan in PlanElec

With PlanElec, you can place PV components on the situation plan, record their electrical structure on the single-line diagram and export both as PDFs. The software reproduces the project data entered. Its indicative self-check can flag supported information, but does not replace an on-site survey or recognised inspection and does not certify AREI compliance.

Sources and reviewed version

The basis is the official AREI/RGIE Book 1 publication: Table 2.23, Part 3, Chapter 7.112, the narrow existing-installation derogation in Part 8 and the dossier requirements in Part 9. Reviewed against V06 on 29 August 2026.