How to Outsource Solar Design in India — A Founder's Playbook

The decision to outsource solar design is made quickly. The implementation is where most Indian EPC founders lose three months they cannot get back. The vendor takes longer than promised. The drawings come back in the wrong DISCOM format. The first brief is a disaster because nobody documented what a good brief looks like. By the time the first outsourced project runs cleanly, the founder has mentally classified outsourcing as “more trouble than it is worth” — which is exactly the wrong conclusion to draw from a process problem.

This playbook exists to eliminate those three months. It is written for EPC founders who have decided to outsource solar design and need to implement the transition without disrupting live projects. It covers the three-phase transition, the brief template that eliminates 80% of revision cycles, how to negotiate an SLA with teeth, and the QC protocol that catches problems before they reach the DISCOM.

Direct answer. Outsourcing solar design in India works when the EPC standardises its brief format, negotiates a written SLA with explicit revision and backup policies, and runs a QC checklist on every deliverable before acceptance. The 3-Phase Founder’s Outsourcing Playbook — Pilot, Parallel, and Scale — is the structured transition that avoids the live-project disruption that kills most outsourcing attempts in the first 60 days. EPCs that follow this playbook reach full outsourcing efficiency within 30 days and recover the transition cost within 60 days.

India’s C&I solar market is executing projects at record speed in 2026, with Mercom India reporting Q1 2026 rooftop installations among the highest on record. EPCs that are still managing engineering as a bottleneck are leaving project capacity — and revenue — on the table.

Phase 1 — Pilot: Running One Project Through the New Partner

Do not migrate your entire pipeline to a new design partner on day one. The Pilot phase runs one project — ideally a mid-complexity C&I project of 100–300 kW — through the complete design cycle with the new partner. This project reveals the operational gaps in your brief process, the partner’s actual turnaround against their promised SLA, and the format quality of their DISCOM drawings.

The Pilot project checklist:

1. Choose a project where you have 7+ days before the design is needed (not a rush project)
2. Write the brief using the standardised brief template (described in the next section)
3. Submit the brief and log the exact time of submission
4. Track the scope confirmation response — is it within 4 hours?
5. Review the draft layout (if a draft review is included in the scope) and give structured feedback
6. Run the QC checklist on the final delivery
7. Submit to DISCOM and track first-pass acceptance vs. revision

The Pilot project is a data-collection exercise. You are measuring the partner, not testing whether outsourcing works as a concept. Document every step. The output of the Pilot phase is a vendor assessment with specific data points — not a gut feeling.

If the Pilot project clears the QC checklist and passes DISCOM first-pass review, the partner is ready for Phase 2. If not, diagnose whether the failure was in the brief (your process) or the delivery (partner’s process) before deciding to continue.

The Brief Template That Eliminates 80% of Revision Cycles

The standardised brief template is the single most impactful operational change an EPC can make when starting to outsource. Most revision cycles — and most first-pass DISCOM rejections on outsourced work — trace back to an incomplete or ambiguous brief. When the designer does not know the correct DISCOM, the inverter model, or the roof structure type, they make assumptions — and assumptions generate revisions.

The Minimum Required Brief Fields:

Field	Why It Matters
Project name and reference number	Version control; links deliverables to project tracker
Site location (full address + lat/long)	IS 875 wind zone; DISCOM identification; irradiance data source
DISCOM name and state	Determines drawing format; determines annexure requirements
Connection category (LT/HT) and sanctioned load	Determines net-meter rating; determines CEIG threshold
System capacity (kWp DC) and module count	Determines BOQ scope; determines structural load
Module make and model (with watt-peak)	Module PAN file for PVsyst; ALMM status; DISCOM compliance
Inverter make, model, and quantity	Inverter OND file; MPPT validation; SLD specification
Roof structure type	RCC slab / tin shed / GI structure / factory — determines structural approach
Deliverables required	List every deliverable: layout, PVsyst, SLD, GA, BOQ, structural, DISCOM drawings
Deadline	The hard deadline, not the preferred date
Client brand / letterhead	White-label: upload your company letterhead template
Special instructions	Any DISCOM-specific notes, client preferences, constraints

This brief template takes 10 minutes to complete per project. It eliminates the 40-minute clarification call that most outsourcing workflows generate for every new brief. Download the brief template from the resource center and standardise it as your team’s submission process for all new projects.

Phase 2 — Parallel: Running In-House and Outsourced Simultaneously

The Parallel phase runs your outsourced partner on new projects while your in-house team continues on projects already in progress. This phase typically lasts 30–60 days — long enough to complete 3–5 outsourced projects and validate the Pilot data at scale.

Why parallel, not immediate full cutover?

Running a full cutover immediately disrupts live projects. Your in-house team’s institutional knowledge of specific DISCOMs, client preferences, and project conventions does not transfer to the external partner in a single handoff. The Parallel phase lets the outsourced partner build context on your projects gradually — while your in-house team maintains continuity on projects in mid-execution.

During the Parallel phase, track these metrics for outsourced vs. in-house:

The comparison data from the Parallel phase gives you the business case for Phase 3. If the outsourced projects are matching or exceeding in-house on quality metrics, at a lower effective cost per project, the case for Scale is self-evident.

Phase 3 — Scale: Full Outsourcing Transition

The Scale phase moves all new project design to the outsourced partner and assigns your freed-up in-house capacity to higher-value activities: client liaison, site survey and data collection, construction supervision, and business development.

The critical step in Scale is the transition protocol for your in-house designer:

• If you have one in-house designer who managed all design work, discuss the role evolution openly. Many designers are relieved to shift from AutoCAD production to quality oversight and construction supervision — roles that make better use of their site knowledge.
• If the designer prefers to remain in a design production role, consider whether they could shift to quality control and DISCOM submission management (coordinating with the outsourced firm rather than producing drawings themselves).
• Redeployment to site supervision is often the highest-value option: an experienced designer on-site catches installation errors that save more per project than their in-house design cost.

Negotiating an SLA With Teeth

A verbal turnaround promise means nothing when your DISCOM submission deadline is in 48 hours. The engagement letter with your design partner must include a written SLA with the following provisions:

What to negotiate into the SLA:

1. Guaranteed turnaround time — specific business days (not “approximately” or “our typical turnaround is”). Standard: 3–5 business days for a complete rooftop package ≤500 kW.

2. SLA restart policy — if the SLA timer restarts on every revision (even client-originated ones), the EPC has no guaranteed timeline. The SLA should restart only for client scope changes, not for revision requests arising from the firm’s own errors.

3. Backup coverage clause — if the assigned engineer is unavailable, who covers the project and at what SLA impact? “We’ll do our best” is not a clause. “Backup coverage by a qualified engineer within 2 hours; no SLA extension” is.

4. Revision policy — how many revision rounds are included in the base price? What constitutes a revision (client-originated scope change) vs. a correction (firm’s own error requiring no charge)? The standard is: unlimited corrections; two revision rounds included; additional rounds billed at a defined rate.

5. Late delivery compensation — if the firm misses the SLA, what is the remedy? A professional engagement letter specifies either a credit against the next invoice or a fee reduction proportional to the delay. Firms that refuse any late-delivery provision are not operationally accountable.

For a comparison of what makes a professional design firm contract vs. a problematic one, the how to choose a solar design partner guide covers the full contract review checklist.

The QC Checklist — What Your Team Checks Before Accepting Any Delivery

Running a QC checklist on outsourced work is not about distrust — it is about maintaining your EPC’s quality standard as an accountable party. The client and the DISCOM hold you responsible for the work, not the sub-contracted design firm. Your QC process is the last gate before a deliverable goes to the client or the DISCOM.

15-point QC checklist for a rooftop design package:

1. System capacity matches the brief (kWp DC, module count)
2. Inverter model and quantity match the brief
3. String voltage (Voc × series count) does not exceed inverter max input voltage
4. String current within inverter MPPT input current rating
5. DC cable sizing specified correctly (25% derating applied)
6. AC cable sizing specified correctly for inverter rated output
7. Net-meter rating correct for the state (inverter output × 110% for Gujarat; sanctioned load for most others)
8. DISCOM-specific title block used (not generic)
9. Metering point shown and consistent between SLD and application form
10. Structural certificate attached and signed by a licensed structural engineer
11. ALMM registration number shown on module specification (if required by the DISCOM)
12. Earthing scheme shown correctly (IS 3043 reference)
13. Fire setback and walkway clearances shown on GA
14. All revision marks cleared (no “draft” watermarks on final package)
15. Your company letterhead used on all deliverables (white-label)

This checklist takes 20–30 minutes per project. It catches 90% of the issues that would otherwise result in a DISCOM revision request.

For more on how to read the specific elements in solar engineering drawings, the how to read solar engineering drawings guide provides a field-engineer-level walkthrough of what each drawing element means and how to verify it.

How Heaven Designs Supports the Outsourcing Transition

Heaven Designs has onboarded 300+ EPC clients through the same 3-phase transition described in this playbook. The standard onboarding package includes:

• Solar Rooftop Detailed Engineering Design — Full IFC-grade package in white-label format with your company letterhead, delivered to your project portal.
• Solar 3D Pre-Design — 48-hour bid-stage layout for the sales team. Submit the client brief in the morning, present the 3D layout in the afternoon meeting.
• Electrical CEIG Drawings — CEIG-ready and DISCOM-format drawings for all major Indian states, updated to current format requirements.
• Download a sample deliverable — See what a complete outsourced design package looks like before you commit to the first brief.

Contact us to confirm DISCOM format coverage for your states and get a pilot-project quote. The onboarding process takes one business day; the first delivery follows 3–5 days after the pilot brief is submitted.

FAQ

How quickly can I start outsourcing after signing with a design partner?

With a mature design partner, you can submit the first project brief within 24 hours of signing the NDA and engagement letter. The first delivery follows 3–5 days later for a standard rooftop project. The total time from “we’ve decided to outsource” to “first delivery in hand” is typically 5–8 business days. If the partner requires more than 2 days of onboarding before accepting the first brief, their intake process is not mature enough for your volume needs.

What if my in-house designer and the outsourced firm produce conflicting designs?

This typically happens when both teams receive the same brief simultaneously during a Parallel phase. Assign a single project to one team and log it clearly in your tracker — avoid parallel design of the same project. If a conflict arises because a client revises scope mid-design while both teams are working, freeze the in-house work and instruct the outsourced firm to incorporate the revision from the current in-house state. Designate one engineer as the “drawing owner” for each active project.

How do I communicate DISCOM format preferences to the outsourced firm?

Include the DISCOM name and state in the standard brief template (the firm maintains its own format library). For DISCOMs where you have specific format preferences developed through previous project experience (e.g., a DISCOM sub-office that prefers a particular drawing scale or annotation style), document these preferences in a “project standards” note that accompanies all briefs to that state. Over 3–5 projects, the firm learns your specific DISCOM conventions.

Should I outsource structural calculations or keep them in-house?

Outsource structural calculations to the same firm handling electrical design. The two deliverables must be consistent — the structural certificate references the electrical BOQ module weight, and the CEIG submission requires both. When structural and electrical are produced by different teams, format inconsistencies (different drawing numbering, different title blocks) create CEIG submission complications. Integrated production from a single firm eliminates this problem.

What is the typical contract length for a solar design outsourcing engagement?

Most EPCs start with a project-by-project engagement (no term commitment) for the first 60–90 days. After 3–5 successful projects, moving to a retainer arrangement (monthly MW band) is cost-effective and ensures preferred queue position during peak design season (October–March in India, when project installations peak ahead of the fiscal year end). Retainer arrangements are typically negotiated for 6–12 month terms with monthly exit provisions.