Choosing a hybrid inverter and the company that fits it

A hybrid inverter earns its premium when storage is part of the plan — now, or within a few years — and the company fitting it can produce three things on request: a named licensed electrical contractor who will energise the AC side, a modelled yield with its assumptions written down, and a commitment to file the EAC connection application before commissioning. A company that cannot produce those is not being compared on price with one that can.

The selection problem is two problems stacked together: specification — which unit, at what rating, coupled to what battery, mounted where — and procurement, meaning which of the companies quoting can be checked against a public record rather than against its own description of itself. Solve only the second and the result is a well-registered company installing an inverter that derates through August.

What can actually be verified

The useful line runs between claims that sit in a public register or on a document with a number on it, and claims that exist only in the conversation.

Verifiable before any deposit changes hands:

• Company identity. Registered name, number, incorporation date, registered office and current directors are searchable at the Registrar of Companies. A trading name on a van is not a company.
• Engineering certification. Where an engineer certifies the design or the structural adequacy of the mounting, that engineer must be registered with ETEK, and registration is checkable by name.
• The electrical contractor. The party carrying out and signing off the electrical work must be licensed to do it. Ask who by name, and whether they are an employee or a subcontractor.
• Product identity. Manufacturer, model and AC rating of the inverter; manufacturer, chemistry, nominal and usable capacity of the battery. "Premium European inverter" is not a model number.
• Compatibility. Hybrid inverters are certified against a published list of battery models. Ask for the page of it that names the battery quoted.
• Insurance. A certificate with a policy number, insurer, limit of indemnity and expiry date.

Not verifiable, and therefore not weightable: years claimed in business with no registration date behind them, installation counts, and manufacturer partner badges that any volume purchaser receives. This site records no ratings, stars or testimonials for any company, and no quantity of them would substitute for a licence number.

Registrations that matter

Three registrations and one record do the real work, and they do different work.

Registrar of Companies establishes that there is a legal person to contract with and whether it is in good standing. That matters most on the warranty side: a battery warranty administered by a company that dissolves becomes a claim against a manufacturer in another jurisdiction, made by the owner personally.

The electrical contractor licence covers reserved work. Connecting a hybrid involves the consumer unit, the earthing arrangement, AC isolation and, where a backup output is fitted, a changeover arrangement separating backed-up circuits from the rest of the board. This is not an area where unlicensed work becomes acceptable because the DC side went well.

ETEK registration is required to practise engineering in Cyprus. It applies wherever a design, a load calculation or a structural assessment of the roof carries a signature — limited on a domestic retrofit, unavoidable on anything three-phase or involving a new supply.

The EAC connection record is not a registration of the installer but the document that ties the installation to the grid. The application is filed by the installer before commissioning, the recorded typical duration is 45 days, and where local network capacity is constrained a load assessment may come first.

Where that assessment bites is geographic. Dense tourist-area feeders — the Germasogeia stretch of the Limassol coast is the standing example — send export applications for load assessment far more often than an inland agricultural connection does. A company working that area will say so unprompted and will have priced it into the programme.

Questions to ask

1. Which inverter model, and is the quoted battery on its compatibility list?

   DC coupling only works between units certified as a pair. A mismatch found at commissioning becomes an AC-coupled retrofit at the owner's cost.

2. What is the modelled clipping loss at the proposed DC:AC ratio?

   Inverter AC rating is normally set below array DC capacity because an array rarely reaches its rated output. At Cypriot irradiance the ratio can run tighter than in northern Europe and clipping losses grow accordingly. The answer is a percentage from a model, not a reassurance.

3. Where is the unit mounted, and what ambient temperature was assumed?

   Derating is the most under-discussed loss in Cypriot systems. A west-facing external wall in Nicosia in August — the widest temperature range on the island — puts a unit at the edge of its envelope during the hours output is highest. A shaded, ventilated position is worth more than most equipment upgrades.

4. What exactly does the backup output cover?

   Which circuits, at what total load, for how long, at what state of charge. "Backup capable" without those four is a feature name. Ask specifically whether the air conditioning sits on the backed-up board — usually it cannot.

5. Who files the EAC application, and who attends a fault?

   The first answer should name the company rather than the owner. The second should separate the manufacturer part warranty from the labour to diagnose and replace, because a long manufacturer warranty with no attending party is an owner posting a unit abroad.

What a good quote looks like

Start from the grid-tied baseline, because that is the figure the hybrid premium sits on top of.

A hybrid inverter and a battery sit above this. How far above depends on usable battery capacity, the inverter's AC rating, whether the supply is single or three phase, and whether the existing consumer unit has room for the additional protective devices. Those four account for most of the spread between two quotes for what looks like the same installation.

A quote that can be assessed itemises module make, model, quantity and total kWp; inverter make, model, AC rating, MPPT count and DC inputs; battery make, chemistry, nominal and usable capacity and rated cycle life; the mounting system and its fixing specification for the roof covering in question; AC and DC protection as separate lines; whether the EAC application and any load assessment are included; commissioning documentation; and warranty terms broken out by component with the administering party named.

Exclusions matter as much as inclusions. The lines that surface later are scaffolding or a mobile platform, a consumer unit upgrade, a supply upgrade from single to three phase, reinstatement of roof waterproofing where fixings penetrate a membrane, and access equipment. On the hillside plots around Peyia that last item is a real cost: steep access roads limit delivery vehicle and crane size, and a battery cabinet is a heavy object that has to reach the plant position somehow.

Two site conditions belong in writing. Within a few hundred metres of the sea — the Kato Paphos frontage being the clearest case — salt-laden air makes marine-grade fixings and an appropriate enclosure rating standard rather than an upgrade, and an indoor-rated inverter has no business on an exposed elevation. In the older apartment stock of Strovolos and comparable 1970s to 1990s blocks, the constraints are usually a single-phase supply, a board with no spare ways, and a riser route to be agreed with the management committee before anything is ordered.

Warning signs

• A yield figure with no orientation, pitch, shading or derating assumptions attached.
• "Battery ready" with no battery named and no compatibility list produced.
• The inverter model withheld until after a deposit.
• The EAC application described as the owner's responsibility.
• A deposit requested before any site survey.
• Pricing quoted per panel rather than per kWp, which hides the balance of system entirely.
• Inverter AC rating set equal to array DC capacity with no clipping figure.
• A backup output sold without a circuit schedule, or no named licensed electrical contractor at all.
• A discount conditional on signing during the visit.

Any one of these is a question. Three together is a different company.

Common questions

Does a hybrid system need a different EAC application from a plain grid-tied one?

It is the same connection process, but the application has to describe the system as installed, including storage and any export limitation. Where the local network is constrained, a load assessment may be requested before approval. The installer files it, and the recorded typical duration of 45 days belongs in the programme rather than at the end of it.

Can a hybrid inverter be added to an array that already exists?

Yes, by replacing the existing string inverter, provided the array's string configuration falls inside the hybrid's MPPT voltage and current windows — a design check, not an assumption. The alternative is AC coupling a separate battery inverter alongside the existing one: an extra conversion stage and a higher total cost, but it leaves a working inverter in place.

Is a three-phase supply required for storage?

Not at domestic scale. It becomes relevant where the backup output must serve three-phase loads such as a borehole pump or larger air conditioning plant. Upgrading the supply is a separate application to the EAC with its own timeline, and it should be identified at survey rather than at commissioning.

What does a hybrid inverter do when the grid fails?

Only what it has been configured and wired to do. Without a backup output and a correctly arranged changeover, a hybrid disconnects on grid loss exactly as a string inverter does, because export into a dead network is not permitted. With a backup arrangement, it runs the circuits placed on the backed-up board for as long as the battery and the load allow.

Does this site rank installers by customer rating?

No. Nothing here records reviews, stars or testimonials. Companies are listed with their registrations, the districts they cover and how long they have been trading, because each of those can be traced to a record. The battery storage section sets out how the field is assembled, and the district coverage pages show which companies work where.

Storage and hybrid installers

2 companies covering this area.

• VS

  Vascon Solar Experts LTD

  Pera Chorio, Nicosia

  Vascon Solar Experts LTD is an energy supplier in Pera Chorio, in the Nicosia district.

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• ES

  Eco Sun

  Agios Nikolaos, Limassol

  Eco Sun is an energy supplier in Agios Nikolaos, in the Limassol district.

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