A solar power diverter takes the surplus electricity your panels make in the middle of the day and sends it to your immersion heater instead of out to the grid. The case for one is simple: a unit you export earns you the Clean Export Guarantee rate — as low as 15.89c with most suppliers — while the same unit used to heat water saves you whatever you'd otherwise pay to heat it. Where you heat water with electricity, that's around 31c a unit, so keeping it is worth more than selling it. Whether the gap covers the €425–€495 a diverter costs depends on how much surplus you actually have and how you heat your water today.
- A diverter is worth most when you heat water with an electric immersion, have real midday surplus, and a low export rate
- The two units sold in Ireland are the myenergi eddi (around €495 ex VAT) and the Solar iBoost (around €425), before fitting
- Bought on its own it carries the standard 23% VAT — the 0% solar rate only applies when it's supplied and fitted with the panels
- There's no SEAI grant for a diverter — the solar grant covers panels, not add-ons
- If you heat water with gas or oil, or you have a battery, a diverter often doesn't pay
What a Solar Power Diverter Actually Does
Your panels make the most electricity in the middle of the day, which is usually when the house is using the least. Without somewhere to put it, that surplus flows out to the grid and you're paid your supplier's Clean Export Guarantee (CEG) rate for it. A diverter intercepts that surplus before it leaves the house and feeds it to your hot-water cylinder's immersion element instead — trickling in just enough power to soak up whatever you're not using, second by second, so nothing is drawn from the grid.
The result is a tank of hot water heated for nothing, paid for by electricity you'd otherwise have sold cheaply. It's the simplest form of self-consumption: using your own generation on site rather than exporting it. The catch is that the saving is only ever the difference between what you'd have been paid to export and what you'd otherwise have spent heating that water — not the full value of the electricity.
The Two Diverters Sold in Ireland
Two units dominate the Irish market. Both do the same core job; the differences are in features, monitoring and whether you also want EV charging in the same ecosystem.
| Unit | Typical Irish price (ex fitting) | Notes |
|---|---|---|
| myenergi eddi | Around €495 ex VAT | Diverts to up to two heaters (e.g. immersion + towel rail), app monitoring, made by the same firm as the zappi EV charger so the two pair neatly |
| Solar iBoost | Around €425 | Long-established immersion diverter, clamps onto the meter tail; simpler feature set, optional remote display |
Add fitting by a registered electrician on top — it's a straightforward job for an installer who's already wiring your panels, and far cheaper bundled into the original install than as a separate call-out later. Prices above are the units alone, checked against Irish retailers in June 2026, and move around with stock and exchange rates.
The Sum That Decides It
A diverter only ever saves you the gap between two numbers: what a unit of surplus would earn exported, and what it saves you used at home. So the whole decision comes down to how you heat your water.
Every unit diverted saves you the day rate you'd otherwise pay — about 31c with Electric Ireland's standard tariff from July 2026 — instead of earning the ~15.89c–25c CEG export rate. That's a gain of roughly 6c–15c per unit you manage to divert. This is the case a diverter is built for.
Gas and oil heat water far more cheaply per unit than electricity does. Diverting solar you could have sold for ~20c to replace heat that costs you less than that can actually leave you worse off — you give up export income to displace a cheaper fuel. Here a diverter usually doesn't stack up.
Here's the immersion case worked through, with figures you should swap for your own. Say a home diverts 600 kWh of surplus over a year — electricity it would otherwise have exported at 20c, worth €120. Used instead to heat water it would otherwise have warmed with the immersion at 31c, that same 600 kWh is worth €186. The diverter's real benefit is the difference: about €66 a year on those assumptions. Against €425–€495 plus fitting, that's a payback north of seven years. Divert more surplus, or sit on a lower export rate, and it comes back faster; divert less, or enjoy a 24c+ export deal, and it stretches out.
The honest summary: a diverter is a sensible €400-odd add-on for an immersion-heated home with plenty of daytime surplus and a poor export rate. It is not a money-spinner, and the better your CEG rate, the weaker the case — because exporting is already paying you well.
VAT and Grants on a Diverter
This trips people up. From 1 May 2023, Revenue applies 0% VAT to the supply and installation of solar panels on private homes, and that zero rate extends to ancillary equipment — batteries, controllers and the like — but only where it's supplied and installed as part of the same solar panel job. A diverter fitted alongside your panels by the installer can fall under the 0% rate. A diverter you buy on its own afterwards is standard-rated at 23% VAT, which is why Irish retailers quote the eddi at €495 ex VAT.
There is no separate SEAI grant for a diverter. The SEAI solar PV grant — worth up to €1,800 in 2026 — pays toward the panels themselves, not bolt-ons like hot-water diverters. So the lesson is the same on both counts: if you want a diverter, the cheapest route is to have it specified and fitted at the same time as your panels, not bought as an afterthought.
When Something Else Beats a Diverter
- You have, or plan, a battery. A home battery stores surplus for any use — lights, appliances, the lot — not just hot water, and at a higher value per unit. If a battery is on the cards, it usually makes a diverter redundant. A diverter only makes sense as the cheaper, water-only alternative when a battery isn't.
- You're on a strong export tariff. If your supplier pays 24c or a premium rate, exporting is already close to what you'd save at home, so there's little gap left for a diverter to capture. Check who pays what on our CEG rate comparison.
- Your surplus is small. A modest array on a house that's occupied during the day exports little, so there's not much for a diverter to harvest. The maths needs real midday surplus to work.
Ask your installer to price a diverter into the quote — fitted with the panels it's cheaper and can qualify for the 0% VAT rate. We match you with SEAI-registered installers in your county who can spec the whole system, diverter included. Free, no obligation.
Get Free Quotes →Frequently Asked Questions
It's worth it mainly if you heat water with an electric immersion, have real daytime surplus and a low export rate. In that case a diverter saves you the difference between your import rate (about 31c a unit) and your export rate (as low as 15.89c) on every unit it captures — a gain of roughly 6c–15c per unit. If you heat water with gas or oil, or you're on a strong export tariff, or you have a battery, a diverter usually doesn't pay.
The unit itself runs about €425 for a Solar iBoost and around €495 ex VAT for a myenergi eddi, with fitting by an electrician on top. It's much cheaper to have it wired in when your panels are installed than as a separate job later — and fitted with the panels it can also qualify for the 0% solar VAT rate rather than the standard 23%.
Both do the same core job of diverting surplus solar to your immersion. The eddi can feed two heaters, has app monitoring, and pairs with the myenergi zappi EV charger if you want both in one ecosystem. The Solar iBoost is long-established and a little cheaper, with a simpler feature set and an optional remote display. For most homes either works; pick on price and whether you want the wider myenergi system.
There's no SEAI grant for a diverter on its own — the solar PV grant covers the panels, not add-ons. On VAT, a diverter supplied and installed as part of your solar panel job can fall under the 0% rate that has applied to solar since 1 May 2023; bought separately afterwards it carries the standard 23% VAT. The cheapest route is to have it fitted with the panels.
A battery stores surplus for any use in the home and captures more value per unit, while a diverter only makes hot water. If you're getting a battery, it generally makes a diverter unnecessary. A diverter is the cheaper, water-only option for homes that aren't installing a battery but want to put their midday surplus to use rather than export it for a low rate.
Yes — a diverter only takes the surplus while your tank is still heating. Once the water is up to temperature, any further surplus flows to the grid as normal and earns your Clean Export Guarantee rate. The diverter simply gives that surplus a more valuable home first, when heating water with the immersion would otherwise have cost you more than the export rate.
Sources: Revenue — VAT on solar panels (0% rate on supply and installation of solar panels from 1 May 2023; ancillary equipment zero-rated only when supplied and installed with the panels); Electric Ireland (standard day unit rate 31.10c/kWh from 1 July 2026); supplier Clean Export Guarantee rates as published May 2026; myenergi eddi and Solar iBoost unit prices from Irish retailers (energyfreedom.ie, solarboss.ie), checked 15 June 2026. Figures move with stock, tariffs and exchange rates — the worked example uses illustrative assumptions you should replace with your own usage.
Published: 15 June 2026. Author: Neil Russell.