Although isn't there an Irish government grant to help cover the cost of the panel + installation? That would make comparing break even times across countries quite difficult.
On top of that there’s an inverter, and if you can’t use all the power immediately you’d need a battery too, which tends to increase the cost.
The biggest cost though is installation.
https://www.citizensinformation.ie/en/housing/housing-grants...
You do make a good point about VAT on electricity bills also being a factor in the break even calculation. In Ireland it's 9% and that's a temporary cost of living measure and will revert to 13.5% in 2030.