Export payments are the half of the solar case that most quotes gloss over. Here is how the Clean Export Guarantee works and why the rate matters less than you would think.
Every quote talks about what solar saves you. Fewer explain what happens to the electricity you generate and do not use, which on a sunny weekday can be most of it.
The scheme. Under the Clean Export Guarantee, your electricity supplier is obliged to pay you for surplus units you export to the grid. It is not a grant and you do not apply for it through SEAI: it comes from whoever you buy your electricity from, and it appears as a credit on your bill.
The rates are not the same everywhere. Suppliers set their own export rate and they differ meaningfully. It is worth checking what yours pays before you assume the figure in a quote applies to you, and worth checking again at renewal, because the export rate is one of the things that moves when you switch.
Why the rate matters less than people expect. Import electricity in Ireland costs considerably more per unit than any supplier pays you to export. That gap is the whole argument for using your own generation rather than selling it. A unit you use yourself is worth the full import price you avoided. The same unit exported is worth the export rate, which is a fraction of that.
This is the real case for a battery, and the real case for shifting heavy loads to the middle of the day. Dishwasher, washing machine, immersion, EV charging: anything you can move into daylight hours is a unit bought at the higher price and replaced by one you already own.
What this means for sizing. A system sized purely to fill the roof will export more and save less than one sized around how the household actually uses electricity. We would rather ask for a year of bills than measure a roof.