CAPEX vs OPEX Solar: Which Financing Model Fits Your Business?

Almost every commercial or industrial solar decision eventually reduces to one question that has nothing to do with panels or inverters: do you own the plant, or do you pay for the power it produces? That’s the CAPEX-vs-OPEX decision, and getting it right matters more than the module brand you pick.

Neither model is universally “better.” Each is the right answer for a different balance sheet, tax position and appetite for upfront spend. Here’s how to actually decide.

The Two Models, in Plain Terms

CAPEX (you own the plant). You pay for the solar system upfront — either fully in cash or through a loan — and you own the asset outright. You keep 100% of the generation, you’re eligible for accelerated depreciation, and the plant is a line on your balance sheet.

OPEX / PPA / RESCO (a developer owns the plant). A solar developer (which may be an EPC company, an investor, or a specialised RESCO) builds and owns the plant on your roof or premises, and you pay only for the electricity it generates — usually at a fixed rate per unit, agreed for a multi-year term through a Power Purchase Agreement (PPA). You put in no capital and take on no ownership.

Side-by-Side: What Each Model Actually Gives You

	CAPEX (You Own)	OPEX / PPA (Developer Owns)
Upfront investment	100%, by you (or via loan)	Zero
Who owns the asset	You	Developer / investor
Who claims depreciation	You (40% WDV, Section 32)	The developer
O&M responsibility	Your team, or a separate AMC	Typically bundled into the PPA
Electricity cost	Zero marginal cost after payback	Fixed ₹/unit rate for the PPA term
Savings over 25 years	Generally highest, since there’s no margin paid to a developer	Lower than CAPEX over the full term, but no capital risk
Balance sheet impact	Capital asset + depreciation	Typically an operating expense
Best suited to	Businesses with available capital, taxable profits to offset, and a long planning horizon	Businesses that want savings without capital outlay, or don’t have enough taxable income to use depreciation fully

Why the “Which Is Better” Question Is the Wrong One

CAPEX generally delivers the highest lifetime savings, because there’s no developer margin baked into every unit you consume for 25 years. But that comparison only holds if you can actually use the depreciation benefit — a company with thin or negative taxable profit in the near term gets far less value from 40% accelerated depreciation than a highly profitable one. In that case, the tax shield that makes CAPEX so attractive on paper is worth much less in practice.

OPEX removes the capital question entirely. If preserving working capital matters more than maximising 25-year savings — say you’re mid-expansion and every rupee of capex is earmarked elsewhere — a PPA at a fixed, typically-below-grid-tariff rate can still deliver real bill reduction with none of the ownership responsibility.

Six Factors That Should Actually Decide Your Model

1. Do you have the capital available without disrupting other plans? If deploying ₹40–50 lakh (for a 100 kW system) or more competes with core-business capex, OPEX removes that tension.
2. What’s your taxable profit position? Accelerated depreciation is only valuable if you have profit to offset. Loss-making or newly profitable units often get more real value from OPEX.
3. How long is your planning horizon at this site? PPAs typically run 10–25 years. If you might vacate or restructure the site sooner, check the PPA’s exit and relocation clauses carefully before signing.
4. Who do you want handling O&M? CAPEX means you own the maintenance responsibility (directly or via a separate AMC contract). OPEX developers usually bundle O&M into the PPA rate, which can be simpler operationally.
5. How much does balance-sheet treatment matter to you? CAPEX adds a depreciating asset (and, if loan-funded, a liability). OPEX is typically treated as an operating expense — relevant if you’re managing specific financial ratios for lenders or investors.
6. What’s the PPA rate actually being offered, and against what escalation? A PPA is only attractive if the fixed or escalating rate stays meaningfully below your grid tariff for the full term — model this against your DISCOM’s tariff trend, not just today’s bill.

A Middle Path: Loan-Funded CAPEX

Many businesses land between the two extremes: taking a solar-specific loan to fund a CAPEX purchase. You get ownership and the depreciation benefit, but spread the cash outflow over the loan term instead of paying upfront. This can combine much of CAPEX’s long-term saving with less of the immediate capital strain — worth modelling against a straight PPA before deciding either way.

What This Looks Like in Practice

Neither model should be chosen off a rule of thumb. The right comparison runs your actual electricity bill, your building’s roof/load profile, and your company’s tax position through both scenarios side by side — CAPEX with financing costs and depreciation benefit included, OPEX at the PPA rate actually being quoted, both over the same time horizon. That’s the only comparison that means anything for your specific business.

Figures and comparisons above are illustrative and not financial advice. Actual outcomes depend on your tariff, consumption profile, tax position, financing terms, and the specific PPA or purchase agreement. Consult your CA or financial advisor before committing to either model.

Where Deon Fits

We run both models with our commercial and industrial customers in Gujarat — full turnkey CAPEX EPC, and OPEX/PPA structures where a developer owns the plant. If you’re not sure which fits, send us your last electricity bill and roof details — we’ll model both against your actual numbers rather than a generic example.

---

FAQ

Is CAPEX or OPEX cheaper for solar?

Over the full 25-year life of a plant, CAPEX generally delivers the highest total savings because no developer margin is paid on every unit consumed — but only if the business can fully use the accelerated depreciation benefit. OPEX has zero upfront cost and can still deliver meaningful savings without capital outlay. The “cheaper” option depends on your specific tax position and capital availability.

What is a solar PPA?

A Power Purchase Agreement (PPA) is a contract under an OPEX/RESCO model where a developer owns and maintains the solar plant on your site, and you agree to buy the electricity it generates at a fixed or pre-agreed rate for a set term, typically 10–25 years.

Who claims depreciation benefits under an OPEX model?

The developer/owner of the plant claims accelerated depreciation under an OPEX or PPA model, not the business consuming the power — because the business never owns the asset.

Can I switch from OPEX to CAPEX later, or vice versa?

Not without renegotiating or exiting the existing agreement. This is why it’s worth modelling both scenarios carefully before signing, and reviewing exit/buyout clauses in any PPA.

Does OPEX solar require any upfront payment at all?

Typically no capital outlay is required from the business under a standard OPEX/RESCO structure — the developer funds construction and recovers its investment through the per-unit PPA rate over the contract term. Specific terms vary by developer and contract.