myenergi zappi, eddi and libbi: using your solar surplus

myenergi is a British manufacturer, based near Grimsby, whose products put your spare solar electricity to use at home instead of exporting it. For a solar home, the two that matter most are the zappi EV charger, which can charge your car from surplus solar, and the eddi diverter, which sends surplus into your hot-water cylinder. Both carry a 3-year warranty as standard and are most useful when you regularly export plenty of power. The libbi battery has a 10-year warranty only as a complete libbi system.

Who makes myenergi products

The manufacturer and warrantor is myenergi Ltd (company number 10261262) of Stallingborough, near Grimsby, listed as active by Companies House on 24 September 2026. Its online shop is run by a sister company, myenergi GB Ltd, and myenergi says the eddi is designed and made at its UK production facilities. Support is on 0333 300 1303.

eddi: hot water from surplus solar

When your panels produce more than your home is using, the eddi sends the surplus to a heating element, usually the immersion heater in a hot-water cylinder, instead of exporting it. It handles resistive loads from 100 W up to 3.68 kW with a mechanical thermostat. myenergi's shop listed the single-phase eddi from £439 on 24 September 2026. It connects to your immersion circuit and needs a current clamp at the supply, so have an electrician fit it; myenergi recommends one too.

Smart diverters have been on HMRC's list of energy-saving materials since 1 February 2024. An eddi that an installer supplies and fits in your home alongside your solar is zero-rated for VAT, a relief due to end on 31 March 2027 (5% after that) unless the government extends it. Bought on its own, an eddi carries 20%.

When diverting beats exporting

Every kWh the eddi diverts is a kWh you no longer export, so it only pays if heating water with it is worth more than your export rate. Per kWh, at Ofgem's October to December 2026 price caps for Great Britain (electricity 26.32p/kWh, which currently includes no VAT; gas 7.97p/kWh including 5% VAT) and two export tariffs checked on 24 September 2026:

A boiler burns more than 1 kWh of gas per 1 kWh of heat, so the real saving is 7.97p divided by your boiler's efficiency. We assume the cylinder loses the same heat either way. Dividing the eddi's £439 unit price (installation not included) by the gain per kWh:

• replacing electric immersion heating, with Octopus Outgoing at 12p (needs Octopus as your electricity supplier): £439 ÷ 14.32p = about 3,070 kWh diverted to cover the unit;
• replacing electric immersion heating, with a 6p export tariff: £439 ÷ 20.32p = about 2,160 kWh;
• replacing gas, with Octopus Outgoing at 12p (needs Octopus as your electricity supplier): the eddi never covers its price unless your boiler is below 66% efficient, because each diverted kWh is worth less than the 12p you give up;
• replacing gas, with a 6p export tariff: £439 ÷ 1.97p = about 22,280 kWh, and less if your boiler is inefficient.

Your export meter readings show how much surplus you have, most of it in summer. Every diverted kWh also comes off what your supplier pays you under its own Smart Export Guarantee tariff. SEG tariffs exist only in Great Britain, and suppliers require MCS certification, or an equivalent, for systems up to 50 kW. Our solar diverter guide compares a diverter with a battery.

zappi: charging your car from solar

The zappi has three modes. FAST charges at full power. ECO tracks your surplus but tops up from the grid when there isn't enough. ECO+ waits for surplus and stops when it runs out. The limit comes from the EV charging standard's minimum current of 6 amps, so myenergi says a single-phase zappi needs about 1.4 kW of surplus to charge on solar alone (6 A × 230 V = 1,380 W), and a three-phase zappi about 4.2 kW.

The minimum green level setting lets you accept a mix on dull days: at 50%, the zappi starts when your surplus reaches about 0.7 kW and takes the other 0.7 kW from the grid or your battery. Our guide to charging an EV with solar shows how far a typical surplus goes.

myenergi's shop listed the zappi from £779 on 24 September 2026, tethered or untethered. myenergi says it should be fitted by a qualified electrician, that no earth rod is needed and that PEN-fault protection is built in, and that the wiring regulations still call for a separate surge protection device. EV chargers aren't on HMRC's list of energy-saving materials, so the 0% installed VAT rate doesn't cover them.

In Great Britain, the Electric Vehicles (Smart Charge Points) Regulations 2021 require home chargers sold since 30 June 2022 to offer default charging hours outside the weekday peaks (8am to 11am and 4pm to 10pm), which you can change or remove, and a random start delay of up to 600 seconds, which you can cancel.

libbi battery and power cuts

The libbi comes in 5, 10, 15 or 20 kWh configurations, with a 3.68 kW or 5 kW single-phase hybrid inverter. On 24 September 2026 the Energy Networks Association type-test register listed the 3.68 kW Libbi-HS3680 under G98 and the 5 kW Libbi-HS5000 under G99 Type A. In Great Britain, G98 covers up to 16 A per phase (16 A × 230 V = 3,680 W single-phase), and the installer notifies the network operator within 28 days. Above that, G99 needs the operator's approval before connection.

libbi is not an uninterruptible supply. In a power cut it disconnects from the grid for about 5 seconds, then powers one dedicated backup circuit, up to the inverter's rating. Your electrician has to move the circuits you want kept on, such as lights, the fridge and the router, to that backup output. Solar panels connected to libbi can keep charging it during an outage while there is daylight. Our battery storage guide explains sizing.

The warranty: what counts

myenergi's current product warranty covers products bought on or after 11 November 2025. The main conditions:

• Register the product in your myenergi account, through the app or the website.
• Installation must be by a competent person, following myenergi's installation manual and the wiring rules.
• Repairs: report faults to myenergi first. If you arrange your own installer to repair the product, the warranty is void; myenergi sends its own engineer or an authorised subcontractor.
• What's excluded: faults caused by incorrect installation (you're sent back to your installer), problems in your existing wiring or solar system, non-myenergi parts, surges and weather damage.
• libbi: 10 years for the battery, inverter and controller only when all three are libbi parts working as one system.
• Moving home: tell myenergi, and the warranty passes to the next owner if you leave the product behind. It doesn't cover products bought second-hand from a private seller or an online resale platform.

Older products are covered by the earlier warranty versions on myenergi's website, dated 24 November 2023, 1 October 2024, 10 November 2025 and an earlier 29 May 2026 edition. Keep the version that applied on your purchase date.

Should you shortlist myenergi?

The zappi is a strong candidate if you have an EV and a roof system that regularly exports well over 1.4 kW. The eddi makes most sense if you heat water electrically or have a low export rate; with gas heating and Octopus Outgoing's 12p export rate (which needs Octopus as your electricity supplier), exporting can be worth more. libbi suits a single-phase home that wants one app for battery, charger and diverter; compare its price and backup wiring with other batteries. When only one of your quotes includes myenergi kit, comparing the quotes line by line shows what the extra hardware adds to the price.

Before you accept a quote with myenergi products

• How much surplus your system exports on a typical sunny day, from your export readings or the installer's estimate.
• For an eddi: how you heat water now, and your export rate.
• For a zappi: tethered or untethered, 7 kW or 22 kW, and whether a surge protection device is included.
• For libbi: the inverter size (HS3680 or HS5000), G98 or G99, and which circuits are wired to the backup output.
• Who registers the products for the warranty, and whether the quote includes the extended warranty.

If a myenergi product goes wrong

myenergi's warranty adds to your legal rights; it doesn't replace them. Who you claim from depends on who sold the product:

• myenergi's online shop: the seller is myenergi GB Ltd. You can cancel within 14 days of delivery under the Consumer Contracts Regulations, and the Consumer Rights Act requires goods of satisfactory quality.
• An installer: the installer answers under the Consumer Rights Act for fitting it with reasonable care and skill, and myenergi's warranty sends installation faults back to them. Being MCS-certified doesn't make an installer a RECC member; if yours is one, RECC requires a workmanship guarantee of at least two years.

Frequently asked questions

Does a zappi work without solar panels?

Yes. In FAST mode it charges from the grid, and you can set timed charging for cheaper overnight rates. The ECO and ECO+ modes only make a difference if you have solar or wind generation.

Is an eddi worth it with a gas boiler?

Often not, if you have a good export tariff. At the October to December 2026 caps, diverted surplus saves at least 7.97p of gas per kWh; exporting it on Octopus Outgoing earns 12p a kWh, but only if Octopus is your electricity supplier, and the rate can change. On a 6p open export tariff, diverting wins by a small margin.

Will libbi keep my house running in a power cut?

Only the circuits wired to its backup output, after a pause of about 5 seconds, and up to the inverter's rating of 3.68 kW or 5 kW.