In Ireland you're paid for surplus solar you send to the grid under the Clean Export Guarantee (CEG). Your electricity *supplier* makes the payment — not ESB Networks — so the rate you get depends on which supplier you're with, and it shows up as a credit on your bill or as a periodic payment. Rates vary between suppliers (often somewhere in the region of the low-to-mid 20s of cent per kWh, though this changes and is worth comparing), so the export rate is a real factor when choosing or switching supplier.
To get paid for *metered* export you generally need a smart meter and to be registered as a microgenerator. The registration happens via the NC6 form, which your installer submits to ESB Networks — make sure they do this, ideally well ahead of install, as it's what gets you into the system. Before your smart meter is reading export, you may receive "deemed" export credits, which are an estimate based on your inverter size rather than your actual readings.
A few practical points: you can only have one supplier for both the electricity you buy and the export they pay you for, so switching supplier moves your export payments too. Suppliers pay on different schedules (some every six months), and there can be lags and the occasional dispute over readings. If you're not seeing export payments at all, check that the inverter's export is actually enabled in its settings — installers sometimes leave the export limit unset, which can make it look like you're generating nothing for export.