How to manage purchase orders for a solar installation project

Purchase order management is one of the most critical — and most commonly mishandled — parts of running a solar EPC company. A missed PO, a wrong quantity, or an unapproved vendor can delay a project by days and cost your team significant rework.

This guide covers how to structure purchase order management for a solar installation project, from BOM creation to goods receipt.

Start with a complete Bill of Materials

Every purchase order starts with a BOM. For a solar installation, your BOM typically includes:

• **Solar panels** — brand, wattage, quantity
• **Inverter(s)** — type (string/micro/hybrid), capacity, quantity
• **Mounting structure** — type (ground mount, roof mount, carport), material (GI/aluminium), quantity
• **DC cables** — 4mm², 6mm², quantity in metres
• **AC cables** — size depends on load, quantity in metres
• **DCDB/ACDB** — distribution boxes with fuse ratings
• **Earthing materials** — GI strip, copper wire, earthing electrodes
• **Conduits and cable trays**
• **Batteries** (if hybrid/off-grid) — capacity in kWh, chemistry
• **BMS and protection devices**
• **Monitoring system** — meters, data loggers, sensors

A common mistake is creating POs directly without a complete BOM, leading to multiple revision orders as items get forgotten. Build your BOM first; generate POs from it.

Splitting the BOM into purchase orders

Rarely does a single vendor supply everything. Typically you'll have:

• **Panel vendor** — solar panels
• **Inverter vendor** — inverters and sometimes string combiner boxes
• **Electrical materials vendor** — cables, conduits, DCDB/ACDB
• **Mounting structure vendor** — racking and hardware
• **Battery vendor** (if applicable)

Create one PO per vendor per project phase. This makes it easier to track delivery status per vendor, follow up on delays, and reconcile invoices.

The PO approval workflow

For any procurement above a threshold (say ₹50,000), have a simple approval workflow:

1. Site engineer raises PO request with items, quantities, and preferred vendor 2. Procurement manager reviews and approves (or returns for revision) 3. PO is sent to vendor with expected delivery date 4. Vendor acknowledges the PO in writing (WhatsApp, email, or portal)

Document this. If you're relying on verbal approvals, you'll eventually run into a dispute about what was ordered and at what price.

Tracking delivery with GRN

A Goods Receipt Note (GRN) is your record that materials arrived at site — and in what condition. When materials arrive:

1. Cross-check delivered items against the PO — quantity, model numbers, specifications 2. Check for physical damage — panels especially should be inspected for microcracks 3. Note any shortages or substitutions 4. Create a GRN and attach it to the original PO

The GRN closes the procurement loop: you know what was ordered (PO), what arrived (GRN), and what's still outstanding.

Common mistakes to avoid

Ordering without price confirmation. Always get a written quotation from the vendor before raising a PO. Verbal price commitments lead to disputes.

No version control on POs. If a PO is revised (quantity change, item substitution), keep a revision history. PO-001 Rev 0, Rev 1, Rev 2 — each revision should be documented.

Mixing project inventories. If you're running multiple projects simultaneously, keep project-wise inventory separate. It's tempting to borrow materials from one project for another, but this creates accounting and delivery chaos.

Paying without GRN. Never release vendor payment without a GRN against the relevant PO. This is a basic control that many small EPCs skip — and regret.

Using software for PO management

At small scale (1-2 projects), a well-structured spreadsheet can work. At 3+ concurrent projects, the coordination overhead grows non-linearly and software starts to pay for itself.

Purpose-built EPC software lets you: - Create POs directly from your project BOM - Manage vendor rate cards so prices auto-populate - Track PO approval status with a workflow - Generate PDFs and send to vendors directly - Record GRNs and match them to POs - See pending deliveries across all projects in one view

Solset CRM includes all of this — and it's free to start. If your procurement is currently spreadsheet-based, it's worth trying a tool that was designed specifically for how solar EPC projects work.