Solar is usually not a small expense. How you finance it changes the total cost, your balance sheet, your tax position, and what happens if you want out in year 8. Get this wrong and you can lose most of the economic benefit of the system.
This guide walks through the four common structures.
Our ROI calculator takes five inputs and gives you a rough estimate of system size, cost range, and payback period. Useful as a reality-check on whatever numbers you're already seeing from quotes.
The four structures
- Cash purchase. Pay upfront, own the system, keep all savings.
- Loan. Borrow money, pay it off over time, eventually own the system.
- Operating lease. Monthly payment for use of the system; don't own it.
- PPA (Power Purchase Agreement). Third party owns and operates the system on your site; you buy only the electricity.
Each has a place. The right one for you depends on capital availability, tax position, risk appetite, and ownership preference.
Cash purchase
How it works: Pay for the system upfront. Own it. All savings accrue to you.
Best return over system life. No interest, no margin going to a financier, no lease fees. You capture 100% of the economic benefit.
Capital constraint. Requires cash on hand that could be used elsewhere. For businesses, the relevant comparison is your cost of capital — if your internal hurdle rate is 15% and solar returns 10% IRR, cash may not be the best deployment even if it's the most profitable solar-specific choice.
Tax treatment. In many jurisdictions, commercial solar qualifies for accelerated depreciation. Cash buyers can use this to improve after-tax returns significantly.
When it's right: Available cash, favourable tax position, long planned site occupancy, preference for full control and no ongoing third-party relationships.
Loan financing
How it works: Borrow the system cost from a bank or specialised solar financier. Repay over 5–10 years. Own the system from day one; own it outright after the loan is paid off.
Capital preservation. Keeps your cash available for other uses. Solar savings often cover most of the loan payment from month one, so the cash-flow impact is modest.
Interest cost. Adds 10–25% to total system cost over the loan life, depending on rate and term. Reduces long-term return compared to cash.
Ownership benefits preserved. Unlike PPA or lease, you still qualify for ownership-based tax benefits (where applicable), and the system adds to your balance sheet.
When it's right: Good credit, want to preserve working capital, happy to own the asset, planning to stay put long-term.
Many banks now offer green loans or solar-specific financing with lower rates than generic business or home loans. Some governments subsidise solar loan interest. Worth asking before defaulting to a standard loan.
Operating lease
How it works: Sign a contract to pay a fixed monthly amount for use of the system. A leasing company owns the hardware. At the end of the lease (typically 7–15 years), you can usually buy the system at a predetermined price, renew the lease, or have the system removed.
Zero upfront cost. Attractive when capex is genuinely constrained.
Off-balance-sheet treatment. In many jurisdictions, operating leases don't appear on the balance sheet as debt. Check current accounting standards in your market.
Split economics. The leasing company takes a margin. Your total cost over the lease life is higher than a cash purchase, typically noticeably higher than a loan.
When it's right: Strong aversion to capex, need off-balance-sheet treatment, short to medium time horizon, willing to pay a premium for simplicity.
Power Purchase Agreement (PPA)
How it works: A PPA provider installs a solar system on your site at no cost to you. They own and operate it. You agree to buy the electricity it produces at a contracted rate (usually 10–30% below grid rate) for a term of 15–25 years.
Truly zero capex. Also zero maintenance, zero operational responsibility. Provider handles everything.
Smallest share of the economic benefit. Most of the savings go to the PPA provider as their return on capital. You get modest ongoing savings vs grid rates.
Long lock-in. Contracts of 15+ years are common. Exit terms can be expensive — early termination or buyout at year 7 can be significant.
No tax benefits to you. The PPA provider owns the system and captures any ownership-based tax benefits.
When it's right: No capex available AND no taxable income to benefit from ownership AND long planned site occupancy AND you value simplicity above total return.
Key clauses to check: annual rate escalator (often 2–4% per year — compounds significantly), exit / buyout terms, ownership transfer at lease-end, performance guarantees, maintenance responsibilities, and what happens if you sell the property.
Decision framework
A simplified version of the logic we walk through with buyers:
- Do you have the cash and a reasonable tax position? → Cash purchase is almost always the best economic option.
- You have good credit but want to preserve cash? → Loan. Interest cost is real but modest, and you still own the asset.
- You need off-balance-sheet treatment or have short time horizon? → Operating lease.
- Truly zero capex available AND no taxable income to use? → PPA. Accept the reduced economic share for zero-hassle installation.
In rough terms, over a 25-year system life, the economic returns rank: Cash > Loan > Lease > PPA. But the right structure for you isn't the highest-return one — it's the one that fits your actual capital position, tax situation, and operational preferences.