Single Line Diagrams for India

Summary

OpenSolar now has an India SLD template. It produces a single line diagram for your project straight from the design you have already built: modules, stringing, inverter, cables and phase all carry across, so there is nothing to re-enter.

The drawing follows Indian conventions. It names the DCDB and ACDB the way a DISCOM reviewer expects, shows the two meters Indian net metering is settled on, includes the three earthing sets and the lightning arrester, and cites the relevant IS and CEA references beside the parts of the drawing they govern.

Once the drawing is generated, it is fully editable. Everything OpenSolar fills in automatically is a starting point, not a locked image. You can move blocks, change labels, correct ratings and add anything your DISCOM asks for.

This article covers finding the SLD tab, generating the drawing, what appears on it, and what you can change afterwards.

Before You Start

• A project with the design finished: modules placed, stringing set and an inverter selected. The SLD reads the design, so an incomplete design produces an incomplete drawing.
• Your organisation's country set to India, so the India template is offered to you.
• Permission to view the design and create an SLD on the project. Ask your organisation admin if the tab is missing but your colleagues can see it.
• A desktop or laptop browser. The SLD page is unchanged on mobile in this release, so generate and edit drawings on a computer.

How to Use It

Step 1.  Open the SLD tab on your project

The tab sits alongside Design and Proposal on the project.

1. Open the project and finish the design: modules, stringing and inverter.
2. Click the SLD tab. The diagram canvas opens with the template list.

Step 2.  Choose the India template and click Apply

1. Pick the India template from the list. It is the one marked as compatible with your country.
2. Click Apply. OpenSolar reads your design, fills in the values and switches on the parts of the drawing your system actually uses: one inverter or two, the right number of strings, single or three phase.

3. The finished drawing appears on the canvas with your project's real figures in place.

   

Step 3.  Check the drawing against your project

Everything on the sheet comes from your design, so a value that looks wrong usually means something is wrong in the design rather than in the drawing.

1. Check the plant summary (DC capacity, AC capacity, module count and inverter) against what you designed.
2. Check the string and MPPT table. String voltages are calculated at your project's own minimum ambient temperature, not at standard test conditions, so they are the figures a reviewer should be checking.
3. Check the cable schedule. Cross-sections are sized by the platform against the permissible voltage drop.

Step 4.  Edit anything you need to, then save

This is the part worth knowing: the generated drawing is a starting point, and every element on it can be changed.

1. Edit directly on the canvas: move a block, change a label, adjust a rating, add a note. It is a full diagram editor.
2. Add anything specific to your project or your DISCOM that is not on the sheet.
3. Save with File › Save, or Ctrl+S / Cmd+S. The drawing is stored against the project so you and your colleagues can reopen it.
4. Editing, exporting and sharing the finished drawing is covered in the companion article, Editing, Exporting and Sharing Your India SLD.

What Is on the Drawing

All of this is drawn for you automatically. Values come from your design unless noted.

• DCDB.  the DC distribution box, between the array and the inverter. Drawn as an enclosure with its contents visible: string fuse, surge protection device and a load-breaking DC isolator.
• ACDB.  the AC distribution box, between the inverter and the consumer or grid side. Contains an MCB or MCCB, a surge protection device, an RCCB, and R-Y-B indication lamps.
• Two meters.  a solar generation meter on the inverter output and a bi-directional net meter at the supply point, with the direction of each marked. Self-consumed energy never crosses the net meter, so the generation meter is what records what the plant actually produced.
• Three earthing sets.  array and structure, inverter and AC, and the lightning arrester, each with its own pit, plus an earth symbol at every earthed point on the diagram tagged to the pit it lands in.
• Lightning arrester.  on its own pit, drawn clear of the array, since it must not be mounted on the module mounting structure.
• Standards references.  IS and CEA references placed beside the parts of the drawing they govern, rather than as a generic list at the bottom.
• Plant, module and inverter blocks.  capacity, DC:AC ratio, module and inverter make and model with their electrical characteristics at standard test conditions.
• String and MPPT table.  modules per string, which MPPT each string enters, and string voltages at your project's minimum ambient temperature.
• Cable schedule.  each run with its cross-section, auto-sized against the permissible voltage drop.
• Notes block.  the standing Indian notes: CEA protection settings, the DC injection limit, earth resistance target and voltage-drop limits.

Everything Stays Editable

The automatic additions get you most of the way there. They do not lock the drawing down.

• Every block, symbol, label and table on the generated sheet can be moved, edited or deleted on the canvas.
• You can add components, notes, dimensions or whole blocks that the template does not produce.
• Ratings and sizes that were assumed from the design can be overwritten with what you are actually installing.
• Editing the drawing never changes the design, and changing the design never changes a drawing you have already saved. They are deliberately separate.
• If you prefer to work in CAD, the exported PDF can be converted to DXF and opened in AutoCAD. See the companion article.

Good to Know

• The drawing is generated from the design at the moment you click Apply. It does not update by itself afterwards. If you change the design, generate it again.
• Regenerating replaces the values that come from the design and does not keep edits you made by hand, so make your manual additions after regenerating, not before.
• Only one SLD is kept per project at a time. Saving again replaces the previous one unless you create a new file.
• The SLD page is unchanged on mobile in this release. Use a desktop browser.
• Systems with more than two inverters or eight strings generate the first eight strings and show a warning on the sheet. Larger systems need the rest added by hand for now.
• DISCOM requirements vary by state. This gives you a complete, correctly drawn starting point; check it against what your own utility asks for before submitting.

What You Gain

• A drawing from the design you already built. Modules, stringing, inverter, cables and phase carry across, so there is nothing to re-enter.
• Indian conventions by default. DCDB and ACDB named and drawn as enclosures, two meters, three earth pits, a lightning arrester and IS/CEA references, without having to remember any of it.
• Temperature-corrected string voltages. Calculated at your project's own minimum ambient temperature rather than at standard test conditions, which is more accurate than most drawings in circulation.
• No agency fee per project. The drawing most projects currently pay a drafting agency to produce comes out of the design instead.
• Editable, not locked. A full diagram editor, so anything specific to your project or your DISCOM can be added before you submit.
• It goes in the proposal. The generated SLD can be embedded in a generated document or proposal PDF alongside everything else the customer receives.

Best Practices

Finish the design before generating. The drawing is only as complete as the design it reads, and regenerating later will overwrite hand edits.

Have someone electrically qualified review the first few drawings your organisation produces, before any of them go to a DISCOM.

Regenerate whenever the design changes. Under the CEA connectivity regulations the drawing forms part of the connection agreement and has to be amended and reissued whenever the installation changes.

What to add or adjust yourself before submitting

The template deliberately leaves some things for you, because they cannot be derived from the design. Complete these on the canvas.

• DISCOM name, consumer number and sanctioned load. These are what the net-metering application is checked against. Fill them into the interconnection block.
• Conductor material and cores on the cable schedule. The platform sizes the cross-section but cannot tell whether a run is copper or aluminium, or how many cores. Small runs are usually copper; larger C&I runs are usually aluminium armoured, often specified as 3.5 core.
• Device ratings you are actually installing. Breaker, fuse and SPD ratings on the sheet are a sensible starting point; overwrite them with the real selections where they differ.
• Anything your state asks for that is not on the sheet. Delhi publishes a detailed drawing checklist; other states differ. Add what your utility expects.
• Battery details, if the project has storage. Battery is not drawn on the India sheet in this release, so add it by hand if your project includes one.
• Extra strings or inverters on larger systems. Above two inverters or eight strings, add the remainder yourself until the limit is raised.
• The other sheets in a submission pack. Equipment layout, earthing layout and key plan are separate drawings and are not produced yet. The earthing information a reviewer needs is on the SLD sheet, but the earthing layout plan is not.

Tell us what your DISCOM sent back. If a drawing is rejected, the reason is the single most useful thing you can send us; it is what shapes the next version of the template.