The accelerated capital allowance (ACA) lets an Irish business write off 100% of the cost of a qualifying solar system against its taxable profits in the year it is installed, instead of spreading that relief across eight years. On a €50,000 system, a company paying the 12.5% corporation tax rate cuts its tax bill by €6,250, and it takes the full benefit in year one rather than a slice each year until the early 2030s.

Grants get the headlines. A cheque from the SEAI is easy to picture, so most businesses chase the grant and stop there. The tax relief sits quietly on a return form, and plenty of owners never claim it, or they buy equipment that does not qualify and lose the relief entirely.

The scheme was extended to 31 December 2030 in Budget 2026, so it is live and worth planning around now. Here is what the relief is worth on solar, why so many businesses leave it on the table, and how to make sure your system actually qualifies.

How Much Is the Accelerated Capital Allowance Worth?

The accelerated capital allowance is worth the full cost of your qualifying solar equipment as a deduction against taxable profits, taken in year one. For a company paying 12.5% corporation tax, a €50,000 system reduces the tax bill by €6,250, and the relief lands immediately rather than trickling in over eight years.

Here is the difference against the standard treatment. Normal plant and machinery gets a wear and tear allowance of 12.5% of the cost each year for eight years. The ACA compresses that same total relief into the first year.

The total relief is the same either way. What the ACA changes is timing, and for a business that matters. Pulling the whole deduction forward frees up cash, cuts taxable profit sharply in the year of purchase, and shortens the payback period on a commercial system once you factor in the grant as well.

The value also depends on the rate you pay. A company saves at 12.5%. A sole trader or farmer paying income tax at the higher rate deducts the same cost against income taxed at a much higher percentage, so the cash benefit is proportionally larger.

Why Businesses Miss This Solar Tax Break

Most businesses miss the accelerated capital allowance on solar for a handful of avoidable reasons. They treat the SEAI grant as the only incentive, buy panels or inverters that are not on the qualifying register, let their accountant default to the standard eight-year write-down, or structure the finance in a way that rules the relief out.

• Grant tunnel vision. The grant is a visible payment, so it gets all the attention. The tax relief can be worth as much again, yet it never gets asked about.
• Equipment not on the register. If the exact model is not on the Triple E register at the time of purchase, the kit does not qualify and the accelerated relief is gone.
• The accountant defaults to 12.5% a year. The ACA is self-assessed and needs no pre-approval, a point set out plainly in the SEAI’s guidance on the accelerated capital allowance, and it is easy to overlook on a busy return.
• Leasing or hiring the system. The equipment must be owned and used in the trade. If it is leased, let, or hired to another party, it will not qualify.
• Claiming in the wrong period. The allowance applies to the accounting period the system was first used, so poor timing between purchase, install, and year-end can cost you.

Fix those five things and the relief is straightforward to secure. Miss any one of them and a genuine saving quietly disappears.

Which Solar Equipment Qualifies for the ACA

Solar equipment qualifies only if the exact model appears on the SEAI Triple E product register at the time you buy it. That covers solar PV panels, inverters, and solar thermal collectors that meet the register’s energy-efficiency criteria, as long as the kit is new, owned by the business, and used in the trade in Ireland.

The core conditions are simple to check before you commit:

• The model is listed on the Triple E register at the point of purchase.
• The equipment is new and unused, not second-hand.
• It is owned by the business and not leased, let, or hired out.
• It is used for the purposes of the trade throughout the period.
• The spend meets the minimum expenditure threshold set for that technology category.

Premium commercial-grade panels and inverters, including the glass-on-glass bifacial panels favoured for regulated sites like data centres and healthcare, are commonly listed. Even so, register status is model-specific, so confirm the precise product before ordering rather than assuming a whole brand qualifies.

How the ACA Stacks With an SEAI Grant

Yes, you can claim the accelerated capital allowance and an SEAI grant on the same solar project, but not on the same euro twice. Any grant you receive reduces the qualifying cost, so you claim the allowance on the net amount you actually paid. Used together, the grant and the tax relief take a serious bite out of the real cost of going solar.

For commercial installations, the SEAI Non-Domestic Microgeneration Grant is worth up to €325,200 per site, and you can stack the tax relief on the balance. A worked outline shows the effect. Say a system costs €50,000 and a grant covers part of it. You claim the grant on the funded portion, then take the accelerated allowance against the amount you paid yourself, so the after-tax cost drops well below the sticker price.

Farmers follow the same rule when pairing solar with an agricultural grant. Whatever the funding source, the principle holds. You cannot claim capital allowances on money someone else paid, so the allowance always applies to your net spend. It is worth mapping the grant and the relief together from the start, which is exactly why the commercial solar grant and the tax side should be planned as one decision rather than two.

How to Claim the ACA on Solar

Claiming the accelerated capital allowance is a self-assessment step, not a separate application. You confirm the equipment is on the register before you buy, keep the paperwork, and enter the allowance on your normal tax return for the accounting period the system was first used. Companies use form CT1, and sole traders and farmers use form 11.

1. Decide on the system and check each model against the Triple E register before purchase.
2. Buy new equipment that the business will own and use in the trade.
3. Keep the invoices and records proving cost and register status.
4. Claim 100% of the qualifying spend in the return for the period the system was first used, following the standard capital allowances rules on Revenue’s capital allowances pages.
5. Bring your accountant in early so the claim is not missed or made in the wrong year.

No approval is needed in advance, so the whole thing rests on buying the right kit and filing it correctly. Get the register check and the timing right, and the relief follows automatically.

Conclusion

Solar already earns its keep over time. The grant and the tax relief together just make the maths land faster, and the accelerated allowance is the piece most businesses forget to claim. Line up the register check, the grant, and the allowance as one plan and none of it slips through the net.

Before you sign off on a system, it pays to arrange a commercial solar assessment early and loop your accountant into the numbers, so the grant and the tax relief are both locked in before the equipment is bought.