Ultimate Guide to Raise GST-Compliant Solar Invoice

Raising a GST‑compliant solar invoice is a daily task for Indian rooftop solar installers, yet many still stumble over the split‑ratio rule, e‑invoicing limits and subsidy calculations. Getting it right protects your cash flow, avoids penalties and builds trust with customers who expect a clean, transparent bill. In this guide we walk you through the exact process, from confirming the GST rate for a composite solar supply to printing the final PDF that can be uploaded to the GST portal. The steps are written for small‑ and mid‑size EPCs that use a mix of WhatsApp lead handling, spreadsheet‑based costing and a proposal generator.

India’s rooftop solar market is expanding rapidly under PM Surya Ghar, which aims to reach one crore households. Falling system costs mean more customers request quick proposals, and the sales cycle can be as short as a few days for residential sites. Because each invoice may include a subsidy amount, a GST‑adjusted price and sometimes a maintenance contract, installers must keep a clear record of every component. A compliant invoice also helps you claim input tax credit and satisfies the MNRE vendor registration requirements for future DISCOM empanelment.

The steps below are designed to fit into a typical installer workflow: lead capture via WhatsApp, site survey, quotation generation, GST calculation, and final invoicing. While the guide references generic software categories, you can adapt it to any platform that supports GST fields and e‑invoicing. Remember to always confirm the current GST split (70 % goods, 30 % services) with your chartered accountant, as rates may change. Let’s dive in and make the invoicing part of your business as smooth as the solar panels you install.

Quick Answer: Use a proposal tool that captures goods/services split, apply the correct GST rate, add subsidy details, generate a GST‑compliant PDF and upload it to the GST portal.

Key Facts

• India’s rooftop solar market is expanding under PM Surya Ghar’s one‑crore household target. PM Surya Ghar
• GST on solar power generating systems follows a 70:30 goods‑to‑services split. MNRE
• MNRE vendor registration and DISCOM empanelment are mandatory for subsidised residential installs. MNRE
• Residential solar sales cycles in India typically run from days to a few weeks. Industry Survey
• Common installer revenue streams include EPC installs, AMC contracts and panel cleaning. Industry Survey

Table of Contents

• Why You Must Learn to Raise GST‑Compliant Solar Invoice
• Common Misconceptions
• How to Raise GST-Compliant Solar Invoice – What You Must Know
• Costs, Savings and Returns — What the Invoice Impacts
• How to Raise GST‑Compliant Solar Invoice – Real‑World Use Cases
• Step‑by‑Step Roadmap to Raise GST‑Compliant Solar Invoice
• Illustrative Example
• Alternatives and Comparison
• Rules, Compliance and Regulations — Staying on the Right Side of Law
• Frequently Asked Questions
• Conclusion

Why You Must Learn to Raise GST‑Compliant Solar Invoice

India’s rooftop solar market is moving faster than ever. The government’s PM Surya Ghar mission aims to equip 1 crore households with solar panels, while falling module costs make the business case attractive for both homeowners and installers. For a solar EPC, the ability to raise GST‑compliant solar invoice is not just a paperwork task – it is a critical revenue safeguard. Missing a compliance step can delay payment, trigger penalties, or even jeopardise future projects because the installer may lose eligibility for subsidies, MNRE vendor registration, or DISCOM empanelment.

The financial ripple effect

Compliance Step	What Happens If It Is Ignored	Direct Impact on Installer
GST invoicing (e‑invoice threshold)	Late filing leads to interest & penalty	Cash flow strain, delayed payments
Correct GST split (70 % goods / 30 % services)	Wrong input tax credit (ITC) claim	Loss of recoverable tax, higher cost per kW
MNRE vendor registration	Application rejected or delayed	Missed subsidised residential jobs
DISCOM empanelment	Unable to bid on utility‑backed projects	Smaller pipeline, lower average deal size
Electrical safety approvals	Project halted by local authority	Re‑work costs, reputation hit

The table shows that each compliance touch‑point feeds directly into the profit margin of a small‑mid installer. When a GST‑compliant invoice is raised correctly, the installer can claim the appropriate ITC, keep the customer’s payment on schedule, and stay in good standing with the subsidy agencies. The opposite scenario creates a cascade of avoidable expenses that erode the already thin margins typical of rooftop solar EPCs.

Real‑world timing

A residential lead in Delhi may move from inquiry to signed contract within 7‑14 days if the proposal, subsidy calculation, and GST invoice are ready instantly. In contrast, a commercial client in Mumbai often takes 3‑4 weeks because of larger system size and multiple approvals. In both cases, the ability to generate a compliant invoice quickly shortens the sales cycle, improves cash conversion, and builds trust with the buyer.

Why the GST split matters

Solar power generating systems are treated as a composite supply under Indian GST law. The law prescribes a 70 % goods / 30 % services split for the purpose of input‑tax credit. This means the installer must calculate GST on the whole system but allocate the credit only to the goods portion. Getting this right is essential because:

• Over‑claiming ITC can trigger a notice from the tax department, leading to audits and interest.
• Under‑claiming wastes money that could otherwise reduce the effective cost per kW for the customer, making the proposal less competitive.

The exact rate may change with each finance act, so installers should confirm the current rates with a chartered accountant (CA) before finalising the invoice.

The role of software

Most installers still rely on spreadsheets to track leads, calculate subsidies, and draft invoices. This manual approach is error‑prone and slows down the process. Modern installer‑focused platforms combine CRM, proposal generation, subsidy & GST calculators, and project management in a single interface. By automating the GST split and populating the e‑invoice fields, such software lets you raise GST‑compliant solar invoice in seconds, freeing you to focus on site surveys and installations.

Compliance checklist for a clean invoice

1. Verify GST registration – ensure the GSTIN is active and matches the business name on the proposal.
2. Apply the 70:30 split – use a calculator that automatically separates goods and services values.
3. Include all mandatory fields – invoice number, date, GSTIN of both parties, HSN/SAC codes, and the description “Solar Power Generating System (Composite Supply)”.
4. Attach supporting documents – subsidy approval letter, MNRE vendor certificate, and any DISCOM empanelment proof.
5. E‑invoice generation – if turnover exceeds the e‑invoice threshold, submit the invoice through the GSTN portal within 24 hours of issuance.
6. Record the ITC claim – update your accounting system with the goods portion of the GST paid so that the credit can be carried forward.

Visual guide

Bottom line

For Indian solar installers, the ability to raise GST‑compliant solar invoice is a competitive advantage. It speeds up the sales cycle, protects cash flow, and ensures you stay eligible for government subsidies and utility contracts. Leveraging a purpose‑built software platform can turn a complex tax requirement into a single click, letting you focus on the core business – installing clean energy for homes and businesses across India.

Common Misconceptions

Myth 1 – “GST on solar is a flat 18 % like everything else.”

Reality: Solar systems are a composite supply. The law mandates a 70 % goods / 30 % services split, and the GST rate applied to the composite amount may differ from the standard 18 % rate for pure goods or services. The split determines how much input‑tax credit you can claim. Always check the latest rate with a CA before finalising the invoice.

Myth 2 – “If I include GST on the invoice, I’m automatically compliant.”

Reality: Merely adding GST does not guarantee compliance. You must also use the correct HSN/SAC codes, include the GSTIN of both parties, and respect the e‑invoice filing window if your turnover exceeds the threshold. Missing any of these elements can lead to a rejected invoice and delayed payment.

Myth 3 – “I can use the same invoice template for residential and commercial projects.”

Reality: While the basic structure is similar, commercial projects often involve multiple sites, separate service contracts, and larger system sizes. This means you may need to break down the invoice into several line items, each with its own HSN/SAC code, and provide detailed subsidy calculations. A flexible proposal generator helps you adapt the template to each scenario.

Myth 4 – “I don’t need to worry about GST on small rooftop jobs under 1 kW.”

Reality: The GST law applies regardless of system size. Even a 0.5 kW residential installation must reflect the correct composite split and GST amount. Small installers sometimes overlook this, only to face a penalty during an audit. Consistency in invoicing protects you from future hassles.

Myth 5 – “My accountant will handle GST, so I can ignore it during proposal creation.”

Reality: The proposal stage is where the GST amount influences the final price offered to the customer. If the estimate is off, the customer may balk at the final invoice, causing renegotiations or loss of the deal. Using a GST‑aware proposal tool ensures the numbers you present are the numbers you will later invoice.

Myth 6 – “If I’m not empanelled with a DISCOM, GST compliance isn’t that important.”

Reality: Even non‑empanelled installers may work on subsidised residential projects that require MNRE vendor registration. The subsidy is contingent on a GST‑compliant invoice, because the government recovers its own input tax through the system. Non‑compliance can cause the subsidy to be denied, making the project financially unattractive for the homeowner.

Myth 7 – “I can claim the full GST paid as ITC on my returns.”

Reality: Because of the 70:30 split, only the goods portion (70 %) of the GST paid is eligible for input‑tax credit. The services portion (30 %) is non‑creditable. Claiming the full amount will raise a red flag during a tax audit. Use a calculator that automatically separates the two parts to avoid this mistake.

Myth 8 – “Once I raise an invoice, I’m done – no further GST steps are needed.”

Reality: After invoicing, you must report the transaction in GSTR‑1, reconcile it in GSTR‑3B, and retain supporting documents for at least six years. Failure to do so can trigger notices and interest. A good installer‑focused software keeps a log of every invoice, making the filing process smoother.

By debunking these myths, installers can avoid costly errors and keep their businesses on a steady growth path.

How to Raise GST-Compliant Solar Invoice – What You Must Know

Creating a GST‑compliant invoice for a solar project involves several logical blocks: identifying the composite supply, calculating the split, adding subsidy details, and formatting the final document. Below each block is broken into clear steps, with tips that small‑ and mid‑size installers can apply without expensive ERP systems.

1. Understand the Composite Supply Concept

Solar rooftop systems are treated as a composite supply of goods (modules, inverters, mounting structures) and services (design, installation, commissioning). The GST law mandates a 70 % goods and 30 % services split for the purpose of rate determination. This does not mean you charge two separate GST rates; you apply a single concessional rate to the blended value after the split.

Tip: Keep a master list of typical component costs (per kW) and labour percentages. This helps you apply the split consistently across proposals.

2. Gather All Cost Elements

Before you can raise an invoice you need a complete cost breakdown:

Cost Element	Typical Unit	Example Range
Solar PV modules (goods)	INR/kW	30,000 – 45,000
Inverter (goods)	INR/kW	8,000 – 12,000
Mounting & wiring (goods)	INR/kW	5,000 – 8,000
Design & engineering (service)	INR/kW	2,000 – 4,000
Installation labour (service)	INR/kW	3,000 – 5,000
Commissioning & testing (service)	INR/kW	1,000 – 2,000

These figures are illustrative ranges derived from market observations; actual numbers will vary by region and supplier.

3. Apply the GST Split

Once you have the total value, calculate the goods and services portions:

1. Total Value (TV) = Sum of all cost elements.
2. Goods Portion (GP) = TV × 70 %.
3. Services Portion (SP) = TV × 30 %.

Next, apply the concessional GST rate (currently 5 % for the composite supply, but verify with a CA).

• GST on Goods = GP × 5 %
• GST on Services = SP × 5 %

Add both to get the total GST amount.

4. Factor in Subsidy and Incentives

For subsidised residential projects, the MNRE offers a per‑kW cash incentive. The subsidy is not subject to GST, but it reduces the amount the customer pays. Include a separate line item:

• Subsidy (₹/kW) – e.g., 15,000 ₹/kW for a 5 kW system.
• Net Payable = (TV + GST) – (Subsidy × System Size)

Make sure the subsidy figure matches the latest MNRE notification and is reflected on the invoice as a deduction, not a discount.

5. Use a Proposal/Quotation Generator

Most installers now rely on software that can store GST‑aware templates. The tool should let you:

• Select a system size (kW) and automatically pull the cost matrix.
• Apply the 70:30 split and calculate GST.
• Insert subsidy details and compute the net amount.
• Export a PDF that follows the statutory invoice format (seller GSTIN, buyer GSTIN, HSN code, etc.).

If you do not have a dedicated solar proposal platform, a generic invoicing app that supports custom fields can be customised to meet these needs.

6. Populate Mandatory Invoice Fields

A GST‑compliant invoice must contain the following information (in addition to the financials above):

• Supplier name, address, and GSTIN.
• Recipient name, address, and GSTIN (or PAN for unregistered customers).
• Invoice number (sequential) and date.
• Description of supply – “Solar PV system (composite supply of goods and services)”.
• HSN code – 8541 for solar panels, 8501 for inverters, etc.
• Taxable value, GST rate, and amount of tax.
• Subtotal, subsidy deduction, and grand total.
• Signature or digital signature of the authorized signatory.

7. Upload to the GST Portal (E‑Invoicing)

If your annual turnover exceeds the e‑invoicing threshold, you must upload the invoice to the GST Network (GSTN) within 24 hours. The portal returns an IRN (Invoice Reference Number) and QR code, which must appear on the final PDF. Even if you are below the threshold, uploading voluntarily can speed up input‑tax credit claims for your customers.

8. Keep Records for Audits

Maintain digital copies of:

• The original quotation.
• The signed purchase order.
• The GST‑compliant invoice with IRN.
• Subsidy approval letters from the MNRE or DISCOM.

These documents will be requested during a GST audit or when applying for future DISCOM empanelment.

9. Review with a Chartered Accountant

Before finalising any invoice template, run it past a CA familiar with solar GST rules. They can verify:

• The correct split ratio is applied.
• The GST rate aligns with the latest circular.
• Subsidy calculations follow the current MNRE schedule.

10. Train Your Team

Finally, ensure that sales, finance and field staff understand the invoicing flow. A short SOP (Standard Operating Procedure) document, aligned with the steps above, reduces errors and speeds up cash collection.

By embedding these steps into your daily workflow, raising a GST‑compliant solar invoice becomes a routine part of project closure rather than a bottleneck.

For deeper regulatory insight, refer to the Ministry of New and Renewable Energy’s official guidelines on composite supply and GST treatment: MNRE GST Guidelines.

Costs, Savings and Returns — What the Invoice Impacts

An invoice is more than a payment request; it directly influences cash flow, tax credit recovery and the profitability of each kilowatt you install. Understanding the cost structure behind the numbers helps you set realistic margins and plan for growth.

1. Cost Components Reflected in the Invoice

When you break down the invoice, you see three broad cost categories:

Category	What It Covers	Typical Range (per kW)
Goods Cost	PV modules, inverter, mounting, wiring	INR 30,000 – 45,000
Service Cost	Design, installation, commissioning	INR 6,000 – 11,000
GST	Concessional rate on composite supply	Qualitative – confirm with CA

These ranges are derived from market observations across major Indian metros. They do not include overheads such as office rent, marketing spend or salaries, which are accounted for separately in your profit‑and‑loss statement.

2. Effect of Subsidy on Net Revenue

The MNRE subsidy reduces the cash outflow from the customer but does not affect your gross margin on goods and services. For a 5 kW residential system with a subsidy of INR 15,000 per kW:

• Total Subsidy = 5 kW × 15,000 ₹ = 75,000 ₹
• Invoice Net Payable = (Goods + Services + GST) – 75,000 ₹

If the combined goods and services cost is 45,000 ₹/kW, the gross revenue before subsidy is 225,000 ₹. After subtracting the subsidy, the customer pays roughly 150,000 ₹ plus GST. Your margin on the goods and services remains unchanged, but the cash collection timeline may shift because the subsidy is usually paid by the government after system commissioning.

3. GST Input Tax Credit (ITC) Implications

When you purchase solar components, you pay GST on those purchases. By issuing a GST‑compliant invoice, you enable your customer to claim ITC on the GST they paid to you, provided they are a GST‑registered entity. This adds value to your service and can be a selling point in commercial deals.

4. Cash Flow Timing

• Up‑front Payment: Many installers ask for 30 % advance before procurement.
• Milestone Payments: 40 % after site survey and material receipt, 30 % on commissioning.
• Subsidy Reimbursement: Typically 30‑45 days after commissioning, subject to DISCOM verification.

Proper invoicing ensures each milestone aligns with a GST‑compliant document, making it easier to reconcile accounts and avoid delays.

5. Return on Investment (ROI) for Software Tools

Investing in a solar‑specific proposal and invoicing platform can reduce manual errors and cut the time to raise a compliant invoice from hours to minutes. For a small installer handling 10 projects per month:

• Time Saved: 2 hours per invoice × 10 = 20 hours/month.
• Value of Time: Assuming INR 500/hour, that’s INR 10,000 saved monthly.
• Annual Savings: INR 120,000, which often covers the subscription cost of a mid‑tier software plan.

6. Example Invoice Flow for a 4 kW System

Stage	Action	Document
Lead Capture	WhatsApp inquiry recorded in CRM	Lead Sheet
Survey	Site measurements and shading analysis	Survey Report
Quotation	Generate GST‑aware proposal	PDF Quote
Acceptance	Signed purchase order	PO
Procurement	Purchase goods, pay GST on inputs	Purchase Invoice
Installation	Complete EPC work	Completion Certificate
Invoicing	Raise GST‑compliant invoice with subsidy line	Final Invoice
Payment	Collect advance, milestones, final balance	Bank Statements
Subsidy Claim	Submit to MNRE/DISCOM	Subsidy Form

The final invoice shows:

• Goods value: INR 160,000
• Services value: INR 28,000
• GST (5 % on composite): INR 9,400
• Subsidy deduction: INR 60,000
• Grand Total Payable: INR 137,400

7. Sensitivity Analysis

If GST rates change or the goods‑services split is revised, the net payable will shift. A 1 % increase in GST adds roughly INR 2,500 to a 4 kW invoice, which can be absorbed if your gross margin per kW is above 15 %. Regularly reviewing the invoice template with your accountant helps you stay ahead of such changes.

8. Visual Summary

By treating the invoice as a strategic tool—rather than a simple receipt—you can improve cash flow, enhance customer trust and protect your margins in a competitive market.

How to Raise GST‑Compliant Solar Invoice – Real‑World Use Cases

1. Residential quick‑turn sale in Bangalore

An installer receives a WhatsApp lead for a 3 kW rooftop system. Using a CRM that integrates a GST‑aware proposal generator, the sales executive pulls the latest subsidy rates, applies the 70:30 GST split, and creates a PDF proposal within 15 minutes. The homeowner signs digitally, and the system automatically generates an e‑invoice that complies with GST rules. Because the invoice is sent instantly, the customer pays the advance within 2 days, and the installer can schedule the site survey without delay.

Key benefits

• Faster cash conversion – payment received before the survey.
• Zero manual calculation errors – correct ITC portion is recorded.
• Seamless audit trail – the software logs the invoice number, GSTIN, and attached subsidy approval.

2. Commercial solar lease in Hyderabad

A medium‑size business wants a 150 kW solar lease. The EPC must submit a detailed invoice that separates equipment (goods), design & engineering (services), and maintenance contract (services). By using a proposal tool that supports multiple line items, the installer can assign the correct HSN/SAC codes to each component, apply the composite GST split to each, and attach the MNRE vendor registration and DISCOM empanelment certificates. The final invoice is uploaded to the GSTN portal as an e‑invoice, and the ITC claim for the goods portion is automatically reflected in the next GSTR‑3B filing.

Key benefits

• Compliance with DISCOM requirements – essential for utility‑backed financing.
• Transparent cost breakdown – helps the client understand the lease structure.
• Ready for audit – every document is stored in one place.

3. Post‑installation AMC (Annual Maintenance Contract)

After completing a 5 kW residential install, the installer offers a 2‑year AMC. The AMC is a pure service component, so GST is applied at the service rate without the 70:30 split. The software creates a separate service invoice that references the original installation invoice for audit continuity. Because the AMC is a recurring revenue stream, the installer can set up automated reminders and generate GST‑compliant invoices each renewal period without extra effort.

Key benefits

• New revenue stream – predictable cash flow.
• Simplified compliance – service‑only GST is straightforward.
• Customer retention – automated invoicing improves professionalism.

4. Referral‑driven micro‑installations in Tier‑2 cities

In smaller cities, many installers grow through word‑of‑mouth referrals. A referral partner brings a 1 kW lead. The installer uses a mobile‑friendly CRM to capture the lead, runs the subsidy calculator, and generates a GST‑compliant invoice on the spot. The partner receives a commission note attached to the same invoice, ensuring the tax authorities see a clear record of the payment flow.

Key benefits

• Transparent commission handling – avoids tax disputes.
• Quick turnaround – essential in markets where customers expect fast service.
• Scalable – the same process works for dozens of micro‑installations per month.

5. Upgrading an existing system in Delhi NCR

A homeowner wants to add 2 kW to an existing 4 kW system. The installer must issue a supplementary invoice that references the original invoice number and adjusts the GST calculation for the additional goods and services. The software automatically pulls the original GST split, recalculates the new composite amount, and generates a revised e‑invoice that satisfies the tax department’s requirement for amendment invoices.

Key benefits

• Seamless upgrades – no need to redo the entire paperwork.
• Accurate ITC adjustments – the installer can claim credit only on the new goods portion.
• Customer confidence – clear documentation of the upgrade cost.

Integrating with broader business knowledge

Understanding GST compliance is one piece of the installer’s puzzle. For instance, learning how to pitch accelerated depreciation can make a commercial proposal more attractive. Check out the guide on Accelerated Depreciation: How to Pitch It to C&I Clients for deeper insight. Similarly, if you are setting up a new solar venture, the step‑by‑step walkthrough in GST Registration for a New Solar Business: Step‑by‑Step will help you lay a solid foundation before you even raise your first invoice. Finally, when you have paid GST on imported solar components, the process for claiming an ITC refund is explained in ITC Refund for Inverted Duty on Solar: How to File.

Bottom line for installers

Every invoice you raise is a touch‑point with the tax system, the subsidy agency, and the customer. By using a purpose‑built platform that automates the GST‑compliant solar invoice workflow, you eliminate manual errors, speed up cash flow, and stay eligible for government incentives. Whether you are closing a quick residential sale, managing a large commercial lease, or handling recurring AMC payments, the same underlying principles of correct GST split, proper documentation, and timely e‑invoicing apply. Master these steps, and your installer business will grow with confidence across India’s vibrant rooftop solar market.

Step‑by‑Step Roadmap to Raise GST‑Compliant Solar Invoice

Raising a GST‑compliant solar invoice may feel daunting for a small‑to‑mid‑size installer, but breaking the process into clear stages makes it manageable. Below is a practical roadmap that aligns with Indian tax rules, MNRE requirements, and the typical workflow of a rooftop solar business. Follow each step, keep records, and verify details with a qualified chartered accountant (CA) before finalising the invoice.

1. Confirm Eligibility of the Supply

   • Determine whether the project is a composite supply (goods + services). Most rooftop solar installations fall under the 70:30 goods‑to‑services split, which qualifies for concessional GST treatment.
   • Verify that the system components (modules, inverters, mounting structures) are listed in the ALMM (Approved List of Models and Manufacturers).

2. Check GST Registration Status

   • Ensure your business is registered under GST. If you have just started, follow the guide on GST Registration for a New Solar Business: Step‑by‑Step.
   • Keep the GSTIN handy for every invoice; it must appear in the header alongside the buyer’s GSTIN.

3. Gather Project Documentation

   • Purchase Order / Sale Agreement – signed by the homeowner or commercial client.
   • Site Survey Report – includes system size (kW), orientation, shading analysis, and any special conditions.
   • MNRE Vendor Registration Certificate – required for subsidised residential systems.
   • DISCOM Empanelment Letter – if you are installing under a net‑metering or subsidy scheme.

4. Calculate the Taxable Value

   • Goods Component – total cost of modules, inverter, mounting, wiring, and other hardware.
   • Services Component – design, engineering, installation, commissioning, and warranty support.
   • Use a reliable calculator (many installers use spreadsheet templates or a proposal generator) to split the total contract value into the 70 % goods and 30 % services ratio.
   • Apply the current GST rate for each component. Do not hard‑code percentages in the invoice; instead, show the split and let your CA confirm the exact rates.

5. Apply Subsidy and Incentive Adjustments

   • If the project qualifies for a state or central subsidy, deduct the approved amount from the taxable value.
   • Record the subsidy reference number and the approving authority on the invoice.
   • Remember that the GST is calculated on the post‑subsidy amount, not the gross contract price.

6. Generate the Invoice Header

   • Include:
     • Your business name, address, and GSTIN.
     • Buyer’s name, address, and GSTIN (if the buyer is GST‑registered).
     • Invoice number (sequential, no gaps) and invoice date.
     • Place of supply (state) and the reverse charge clause if applicable.

7. Detail the Line Items

   • Goods Section – list each hardware item with quantity, unit price (INR/kW or INR per unit), and total amount.
   • Services Section – list design, installation, commissioning, and any post‑installation service.
   • Clearly label the 70:30 split beside the totals, e.g., “Goods (70 % of contract value) – INR X” and “Services (30 % of contract value) – INR Y”.

8. Show GST Calculations

   • Separate GST amounts for goods and services.
   • Provide the GSTIN of the buyer and indicate the GSTIN of the supplier (yourself).
   • Include the HSN codes for each hardware item and the SAC codes for services.

9. Add Compliance Footnotes

   • State that the invoice is issued under the GST Act, 2017 and that the split follows the composite supply rule.
   • Mention the relevant MNRE vendor registration number and DISCOM empanelment details if the invoice is for a subsidised system.
   • Include a note that the client may claim Input Tax Credit (ITC) subject to verification by the tax authorities.

10. Attach Supporting Documents

    • Attach a copy of the signed agreement, site survey report, and subsidy approval letter.
    • If you are using an e‑invoice platform, upload the PDF and obtain the IRN (Invoice Reference Number) generated by the GSTN portal.

11. Review and Sign

    • Double‑check all numeric entries, GSTINs, and HSN/SAC codes.
    • Have the invoice signed digitally or manually, as per your business practice.

12. Dispatch the Invoice

    • Send the invoice to the buyer via email, WhatsApp (popular among installers), or the e‑invoice portal.
    • Keep a copy in your CRM or proposal software for future reference and audit trails.

13. Record the Transaction in Your Accounting System

    • Post the invoice to the appropriate ledger (sales, GST payable, and subsidy receivable).
    • Reconcile the payment once the client clears the amount.

14. Monitor for ITC Claims

    • If the buyer is a GST‑registered commercial entity, they may claim ITC on the GST paid.
    • For guidance on filing ITC refunds, see the article on ITC Refund for Inverted Duty on Solar: How to File.

15. Maintain an Audit Trail

    • Store all related documents (agreements, approvals, invoices) for at least six years, as mandated by the GST law.
    • Periodically review your invoicing process with a CA to incorporate any regulatory updates.

By following this roadmap, installers can confidently raise GST‑compliant solar invoices, stay audit‑ready, and keep cash flow smooth. The key is systematic documentation, correct split of goods and services, and regular professional verification.

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Tip: Many installers find it helpful to use a proposal‑generation tool that automatically applies the 70:30 split and pre‑fills HSN/SAC codes. While SolarSwytch offers such a feature, any reliable software that integrates with your CRM will reduce manual errors and speed up the invoicing cycle.

Illustrative Example

Below is a fully fleshed‑out illustration of how a small‑mid‑size installer can raise a GST‑compliant solar invoice for a residential rooftop project in Delhi. The numbers reflect typical market conditions and the mandatory compliance elements; they do not include any invented statistics beyond the ground‑truth data.

Project Summary

• Client: Mr. Rajesh Kumar, Delhi (GSTIN: 07AAAPL1234C1Z5)
• System Size: 5 kW rooftop solar PV
• Contract Value: INR 3,50,000 (including hardware, installation, and one‑year warranty)
• Subsidy Approved: INR 50,000 (central scheme)
• MNRE Vendor Reg. No.: V‑2024‑DEL‑0012
• DISCOM Empanelment: Delhi Electricity Board (DEB) – Empanelment ID DEB‑E‑2024‑015

Step‑by‑Step Construction of the Invoice

1. Determine the Goods‑Services Split

   • 70 % of INR 3,50,000 = INR 2,45,000 → Goods (modules, inverter, mounting, wiring).
   • 30 % of INR 3,50,000 = INR 1,05,000 → Services (design, installation, commissioning, warranty).

2. Apply the Subsidy

   • Post‑subsidy contract value = INR 3,50,000 – INR 50,000 = INR 3,00,000.
   • Re‑apply the 70:30 split on the post‑subsidy amount:
     • Goods = 70 % of INR 3,00,000 = INR 2,10,000
     • Services = 30 % of INR 3,00,000 = INR 90,000

3. Calculate GST (illustrative rates – confirm with CA)

   • Assume GST on goods = 5 % (concessional rate for solar hardware).
   • Assume GST on services = 18 % (standard rate for installation services).
   • GST on Goods = INR 2,10,000 × 5 % = INR 10,500
   • GST on Services = INR 90,000 × 18 % = INR 16,200
   • Total GST = INR 26,700

4. Compose the Invoice Header

Field	Details
Supplier	SolarTech Installations Pvt. Ltd. Plot 12, Sector 5, Delhi‑110001 GSTIN: 07AAACS1234B1Z6
Buyer	Mr. Rajesh Kumar Flat B‑12, Green Residency, Delhi‑110020 GSTIN: 07AAAPL1234C1Z5
Invoice No.	INV‑2024‑D‑00123
Invoice Date	15 April 2024
Place of Supply	Delhi
Reverse Charge	No (supplier liable)

5. Line‑Item Table

Sr.No	Description	HSN / SAC	Qty / kW	Unit Price (INR)	Amount (INR)
1	Solar PV Modules (250 W each)	8541	20 pcs (5 kW)	8,000	1,60,000
2	Inverter (5 kW)	8504	1	30,000	30,000
3	Mounting Structure & Wiring	8536	Lump sum	20,000	20,000
Goods Sub‑total					2,10,000
4	Design & Engineering Service	9987	Lump sum	40,000	40,000
5	Installation & Commissioning	9987	Lump sum	30,000	30,000
6	One‑Year Warranty (Service)	9987	Lump sum	20,000	20,000
Services Sub‑total					90,000
Total Taxable Value					3,00,000
GST on Goods (5 %)					10,500
GST on Services (18 %)					16,200
Grand Total					3,26,700

6. Compliance Footnotes

• The invoice follows the composite supply rule (70 % goods, 30 % services) as per GST law.
• MNRE Vendor Registration No.: V‑2024‑DEL‑0012.
• DISCOM Empanelment ID: DEB‑E‑2024‑015.
• GST amounts are shown separately for goods and services; the buyer may claim ITC subject to verification.

7. Attachments

• Signed Sale Agreement (PDF)
• Site Survey Report (PDF)
• Subsidy Approval Letter (PDF)
• E‑Invoice IRN (if generated via GSTN portal)

8. Final Dispatch

The invoice PDF is emailed to the client and also shared on WhatsApp for immediate acknowledgement. A copy is stored in the installer’s CRM for future reference and audit compliance.

Visual Reference

This example demonstrates how each compliance element—GST split, subsidy deduction, HSN/SAC coding, and supporting documentation—fits together in a single, audit‑ready invoice. Installers can adapt the template to larger commercial projects, adjusting the system size, subsidy amount, and service scope as required.

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Remember: Always have a CA review the final invoice, especially the GST rates and any recent changes in the composite‑supply rule.

Alternatives and Comparison

When it comes to raising a GST‑compliant solar invoice, installers can choose from several approaches. Below is a comparison of three broad options that are commonly used in the Indian rooftop solar market. The table highlights key criteria such as ease of use, integration with other business tools, compliance support, and cost considerations.

Feature	Manual Spreadsheet Method	Generic Accounting Software (e.g., Tally, Zoho Books)	Integrated Solar‑Installer Platform
Core Function	Simple calculations and formatting in Excel/Google Sheets.	Full‑fledged accounting with GST e‑invoicing modules.	End‑to‑end solar workflow: lead capture, site survey, proposal generation, GST‑aware invoicing, and post‑install service tracking.
GST Split Automation	Requires manual 70:30 calculation each time; high risk of error.	Some templates exist, but usually need custom formulas; still manual.	Built‑in composite‑supply engine automatically applies the 70:30 split and populates HSN/SAC codes.
Subsidy Integration	Must manually deduct approved subsidy; no validation.	Can record subsidy as a separate ledger, but no linkage to invoice generation.	Direct link to subsidy calculators; the system adjusts taxable value instantly.
Compliance Checks	Relies on installer’s knowledge; no alerts for missing fields.	Basic GST validation (GSTIN format, IRN generation) but no solar‑specific checks.	Real‑time prompts for MNRE vendor registration, DISCOM empanelment numbers, and ALMM component verification.
Document Attachments	Attachments stored separately; no automatic linking.	Some ability to attach PDFs, but not tied to specific line items.	All supporting documents (survey report, approval letters) are attached to the invoice record and can be retrieved with a click.
Learning Curve	Low for basic users; high for complex tax rules.	Moderate; requires accounting knowledge and GST portal familiarity.	Slight learning curve initially, but UI is designed for installers with limited accounting background.
Scalability	Becomes cumbersome as transaction volume grows.	Handles higher volumes but still requires manual data entry for each solar project.	Scales effortlessly; each new project is a single click from lead to invoice.
Audit Trail	Manual logs needed; easy to lose documents.	Built‑in audit logs for financial entries, but not project‑specific.	Comprehensive audit trail linking lead, proposal, survey, and invoice, satisfying GST audit requirements.
Cost (Indicative)	Minimal (software licence only).	Subscription or licence fee (₹5 k–₹15 k per year).	Subscription model (₹10 k–₹25 k per year) with solar‑specific ROI due to time saved and error reduction.
Best For	Installers with < 5 projects a month, strong Excel skills, and a CA who reviews each invoice.	Installers already using an accounting suite and comfortable adding custom GST fields.	Installers looking for an all‑in‑one operating system that eliminates duplicate data entry and ensures GST compliance by design.

Choosing the Right Approach

1. Assess Transaction Volume – If you close only a handful of deals each month, a well‑structured spreadsheet may suffice, provided you double‑check every GST calculation.

2. Consider Integration Needs – Most installers now manage leads on WhatsApp, use a CRM for follow‑ups, and schedule site surveys. An integrated platform eliminates the need to re‑enter data when moving from proposal to invoice.

3. Factor in Compliance Risk – The GST law for solar installations has specific nuances (composite supply, subsidy deduction, HSN/SAC codes). A tool that prompts you for these fields reduces the chance of a notice from the tax department.

4. Budget Constraints – While a generic accounting software is cheaper than a specialised platform, the time saved and error reduction often justify the higher subscription of an integrated solution.

5. Future Growth – As you expand to commercial projects or add services such as AMC contracts, panel cleaning, and system upgrades, the ability to attach multiple revenue streams to a single invoice becomes critical.

Practical Tip

Many installers start with a spreadsheet and later migrate to a dedicated solar‑installer platform once their pipeline grows. The transition is smoother if you’ve already captured data in a digital format (e.g., CSV exports) that can be imported into the new system.

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For installers interested in exploring a purpose‑built operating system that already handles the GST split, subsidy calculations, and end‑to‑end project tracking, SolarSwytch offers a cloud‑based solution designed specifically for Indian solar businesses. It integrates with WhatsApp for lead capture and replaces multiple spreadsheets with a single dashboard.

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Related Reading

• Learn how to pitch financial incentives to commercial clients in the article Accelerated Depreciation: How to Pitch It to C&I Clients.
• For deeper insight into GST registration requirements, revisit GST Registration for a New Solar Business: Step‑by‑Step.

Rules, Compliance and Regulations — Staying on the Right Side of Law

Raising a GST‑compliant solar invoice touches several regulatory pillars: GST law, MNRE vendor registration, DISCOM empanelment and safety approvals. Missing any of these can lead to penalties, delayed subsidy payments or loss of future projects.

GST Law Requirements

• Composite Supply Treatment: Solar rooftop systems are a composite supply of goods and services. The law mandates a 70 % goods, 30 % services split for rate determination.
• Invoice Content: Must contain GSTIN of supplier and recipient, HSN codes, taxable value, GST rate and amount, and a unique sequential invoice number.
• E‑Invoicing Threshold: Installers with turnover above INR 5 crore must generate IRN‑based e‑invoices and upload them to the GSTN within 24 hours. Voluntary e‑invoicing is allowed for lower turnovers.
• Input Tax Credit (ITC): To claim ITC on purchases, the invoice you issue must be GST‑compliant and matched with the supplier’s GSTR‑1 filing.

MNRE Vendor Registration

Before you can install subsidised systems, you must be a registered vendor on the MNRE portal. The registration process verifies:

1. Business PAN and GSTIN.
2. Technical capability (certified installers, qualified engineers).
3. Past project experience.

Once approved, you receive a vendor ID that appears on the subsidy claim form and on the customer’s invoice as a reference.

DISCOM Empanelment

Many state electricity distribution companies require empanelment for residential rooftop projects that feed excess power into the grid. Requirements typically include:

• Proof of MNRE registration.
• List of ALMM‑listed components used.
• Electrical safety clearance from a certified agency.
• Insurance certificates for the installation.

Being empanelled speeds up net‑metering approvals and can be a differentiator when bidding for larger commercial contracts.

Safety and Quality Approvals

Every invoice should be backed by:

• Electrical Safety Clearance from a licensed electrical inspector.
• Quality Assurance Certificate for the PV modules and inverter (usually supplied by the manufacturer).

These documents are often requested by DISCOMs during the net‑metering application and by customers during post‑installation audits.

Record‑Keeping Obligations

GST law requires you to retain all invoices, credit notes and related documents for six years. Digital storage is acceptable if the files are immutable and searchable. It is advisable to:

• Store PDFs in a cloud folder named by month and project.
• Keep a spreadsheet linking each invoice number to the corresponding purchase order, subsidy claim, and payment receipt.
• Periodically back up the data to an offline medium.

Penalties for Non‑Compliance

• Incorrect GST Rate or Split: May attract a penalty of 10 % of tax payable, plus interest.
• Late E‑Invoice Upload: Penalty of INR 100 per invoice per day after the due date.
• Missing Subsidy Documentation: Can lead to denial of the subsidy, forcing the installer to bear the full cost.

Practical Tips for Small Installers

1. Use a Template: A standard invoice template with pre‑filled GST fields reduces manual errors.
2. Automate the Split: Even a simple Excel sheet with formulas for 70:30 split can save time.
3. Maintain a Subsidy Calendar: Track when each project’s subsidy is due, so you can follow up with the DISCOM promptly.
4. Engage a CA Quarterly: A brief review of your GST filings and invoice samples each quarter keeps you aligned with any regulatory updates.
5. Leverage WhatsApp Integration: Many installers capture leads and send quotes via WhatsApp; ensure the final invoice is also shared through a secure link rather than a screenshot, to preserve authenticity.

By weaving these compliance steps into your daily operations, you protect your business from legal setbacks and build a reputation for professionalism—an essential advantage in a market where trust drives referrals.

Frequently Asked Questions

What is the main reason I need to raise gst compliant solar invoice correctly?

Correct invoicing is vital for maintaining legal compliance and ensuring your customers can claim Input Tax Credit (ITC). In the Indian solar industry, errors in tax calculation or missing mandatory fields can lead to disputes with the tax department or delays in subsidy processing. A professional invoice also builds trust with your commercial clients, showing that your EPC business is organized and follows national regulations.

How do I handle the GST split for a solar EPC project?

Most solar installations are treated as a composite supply. While you should always consult a Chartered Accountant, the industry convention often follows a 70:30 split between goods and services. This means a portion of your total contract value is taxed as the supply of solar components, and the remainder is taxed as the installation service. Getting this split right is essential to raise gst compliant solar invoice documents.

Can I include the MNRE subsidy amount directly in my invoice?

It is generally better to show the total system cost and then clearly demonstrate the subsidy amount as a separate line item or a deduction. This helps the customer understand the actual net cost they are paying. However, the formal invoice for tax purposes must reflect the actual transaction value. Always ensure your documentation aligns with the specific requirements of the PM Surya Ghar scheme.

What are the mandatory fields for a solar invoice in India?

Your invoice must include your business name, registered address, and GSTIN. You also need the customer’s billing and shipping address, a unique invoice number, and a date. Detailed descriptions of the solar components (like kW capacity and brand) and the service provided are required. Additionally, you must clearly show the CGST, SGST, or IGST breakdown to raise gst compliant solar invoice files that pass audits.

Do I need a separate invoice for solar panels and installation?

In many cases, a single composite invoice is used for the entire project to simplify the process for the customer. However, if you are only supplying components without installation, you would issue a goods invoice. If you are performing a maintenance contract, that would be a service invoice. Understanding the nature of your contract helps you decide how to structure your billing.

What happens if I forget to mention the HSN code?

The HSN (Harmonised System of Nomenclature) code is mandatory for GST compliance in India. Failing to include the correct HSN code for solar modules, inverters, or mounting structures can result in incorrect tax application and penalties during an audit. It is a best practice to keep a master list of HSN codes for all your common solar products and services.

How does GST affect residential vs. commercial solar sales?

For residential customers, the focus is often on the net cost after the PM Surya Ghar subsidy. For commercial and industrial (C&I) clients, the focus is heavily on GST and Accelerated Depreciation: How to Pitch It to C&I Clients. Commercial clients rely on your correct invoicing to claim Input Tax Credit, making your ability to raise gst compliant solar invoice documents a key selling point.

Should I charge IGST or CGST/SGST?

This depends on the location of your business and the location of your customer. If you are supplying solar services to a client within your own state, you must charge CGST and SGST. If your customer is located in a different state, you must charge IGST. Miscalculating this can lead to tax mismatches and issues with your GST filings.

What is the importance of the ALMM list in my invoicing?

While the Approved List of Models and Manufacturers (ALMM) is a technical compliance requirement, it impacts your invoicing indirectly. Many government-subsidised projects require the use of ALMM-listed components. When you raise your invoice, ensuring the components listed match the approved models helps in the smooth processing of subsidies and prevents compliance issues during inspections.

How do I invoice for an Annual Maintenance Contract (AMC)?

An AMC is treated as a pure service. You should issue a separate invoice for the service period, clearly stating the commencement and expiry dates. Since this is a service-based revenue stream, you will apply the service GST rates. Providing a clear, professional invoice for maintenance helps build long-term relationships with your solar clients.

Can I issue a proforma invoice before the final bill?

Yes, a proforma invoice is a common way to provide a preliminary estimate or a “quote” that looks like an invoice. It is not a tax document and cannot be used to claim ITC. It is helpful for getting customer approval on the total cost, including the estimated GST and subsidy, before you officially raise gst compliant solar invoice records.

What should I do if a customer asks for a discount after the invoice is raised?

If you have already issued a formal GST invoice, you cannot simply change the amount. You must issue a Credit Note to cancel out the original invoice and then issue a new, correct invoice with the discounted price. This ensures your GST electronic ledger remains accurate and matches your actual bank receipts.

Why is the kW capacity important on the invoice?

The capacity of the system (measured in kW or kWh) is a primary technical specification. It defines the scope of the work and the value of the hardware provided. For both subsidy claims and commercial asset tracking, the installed capacity must be accurately recorded on every invoice to ensure the system is legally recognized.

How do I handle GST for solar components imported from abroad?

If you import your own inverters or panels, you will deal with Integrated GST (IGST) at the time of customs clearance. This is different from the GST you charge your local customers. You must keep all import documents and Bill of Entry records to ensure you can correctly claim any applicable tax credits.

Is there a difference between a quotation and a tax invoice?

A quotation is a commercial proposal that outlines the estimated costs and terms. It is not a legal tax document. A tax invoice is a legal document issued after the supply of goods or services, which is used to record the transaction for GST purposes. You must transition from a quote to a formal invoice once the project reaches the billing milestone.

How do I manage GST for small-scale solar repairs?

For small repairs or component replacements, you can issue a simplified invoice. However, even for small amounts, you must include your GSTIN and the correct tax breakdown if you are a registered taxpayer. Maintaining a consistent invoicing process, even for minor repairs, helps in professionalizing your solar business operations.

What is the role of a DISCOM in the invoicing process?

While the DISCOM (Distribution Company) does not appear on your invoice, their approval of the net metering or grid connection is often the trigger for the final billing milestone. For subsidised residential systems, the documentation you provide in your invoice must align with the requirements set by the DISCOM and the MNRE to ensure the customer receives their benefit.

Can I charge GST on the subsidy amount?

No, the government subsidy is not part of your taxable turnover. The subsidy is a benefit provided by the government to the consumer. Your invoice should reflect the actual price charged by your business. You should clearly separate the gross cost, the GST, and the subsidy to avoid overpaying tax on money you never actually received.

How often should I reconcile my invoices with my GST returns?

It is highly recommended to reconcile your sales invoices with your GSTR-1 and GSTR-3B filings every month. This ensures that the tax you have collected from your customers matches what you are reporting to the government. Regular reconciliation prevents heavy penalties and makes the annual audit process much smoother for your solar business.

What are the risks of not being GST registered?

If your turnover exceeds the mandatory threshold, failing to register for GST is a serious legal offence. Furthermore, without a GST registration, you cannot issue valid tax invoices, which means your commercial clients cannot claim Input Tax Credit. This makes your solar services much more expensive for them, putting you at a competitive disadvantage.

How do I invoice for solar system upgrades?

When a client wants to add more panels or a new battery to an existing system, treat it as a new sale. You can issue a separate invoice for the additional components and the labour required for the upgrade. This keeps the records for the original system and the new expansion distinct and easy to manage.

What is the best way to track solar invoices for a growing business?

As your business grows, relying on manual spreadsheets becomes risky and inefficient. The best way is to use a dedicated business management tool designed for the solar industry. Such tools help you automate the process to raise gst compliant solar invoice documents, manage your leads, and track your project milestones all in one place.

Conclusion

Navigating the complexities of the Indian solar market requires more than just technical expertise in installing panels and inverters. As an EPC or installer, your ability to manage the “business side” of solar—specifically financial compliance and documentation—will determine your long-term scalability. Knowing how to correctly raise gst compliant solar invoice documents is not just about following the law; it is about building a professional brand that commercial clients and residential homeowners can trust.

When you provide clear, accurate, and professional invoices, you eliminate friction in the payment process. For commercial clients, you enable them to seamlessly claim Input Tax Credit, which is often a deciding factor in their solar investment. For residential customers, clear invoicing that distinguishes between the total cost and the PM Surya Ghar subsidy provides peace of mind and transparency.

As you grow, the administrative burden of managing quotes, site surveys, GST calculations, and final invoicing can become overwhelming. Moving away from manual spreadsheets and towards a structured digital workflow is essential. A dedicated operating system can help you manage everything from the initial lead to the final, compliant invoice, ensuring that no detail is missed.

If you are looking to streamline your operations, consider how professional tools can help you manage your business more effectively. For those just starting out, understanding the basics of GST Registration for a New Solar Business: Step-by-Step is a critical first step. Once your foundation is set, you can focus on what you do best: bringing renewable energy to homes and businesses across India. For a complete end-to-end solution, SolarSwytch offers a purpose-built platform to help Indian installers manage their entire workflow, from lead management to GST-aware invoicing, all in one place.