For discussion by the client, Xander Teenus OÜ and an electrical specialist. This is not an official contractor document, electrical design, quotation or grid-connection approval.
Parameter
Known information
Status
Solar panels
25 × 410 W = 10.25 kW
Listed in the 2022 invoice; actual delivery and the panel datasheet have not been confirmed
Inverters
3 Growatt units; the 2022 invoice says “3000 Tl1-S”
No exact match for this designation was found in the materials reviewed. The main hypothesis is single-phase Growatt 3000-S; check the nameplate of all three units.
Cable route
About 30 metres, underground conduit
Reported by the client; the conduit has not been checked for suitability
Energy storage
A battery is not part of the original kit
Option under consideration
Main fuse
Unknown
Fuse rating needed
Water heater
Present; power and number of phases unknown
Datasheet needed
House supply
Three-phase, 230/400 V
Assumption
Export to the grid
Unknown
Elektrilevi conditions needed
Equipment
Panel and inverter items appear on the 2022 invoice
Delivery, actual models and individual device prices have not been confirmed
Unknown values are not replaced by example specifications from model cards.
1 · Grid operation
A — permitted export, or B — technically controlled zero export. Both operate in parallel with the grid and require the grid operator's conditions; B has not been confirmed as feasible with the actual inverters.
2 · Optional additions
A controlled water heater and a battery can each be added to A or B independently. A battery requires separate compatible equipment.
Inverter location · clarified
The three inverters will be outdoors by the panels; an approximately 30 m AC line runs to the house distribution board. Cable, protection and conduit suitability require engineering checks.
Compare solutions and view the principle diagram
A permits export within the operator's conditions; B means zero export, whose technical feasibility with the actual inverters has not yet been confirmed. The water heater and battery are independent options. The inverters are outdoors by the panels; an AC line runs to the house. Inverter model must be confirmed from the nameplates.
1 Option 1 to compare
Grid operationAdditions
2 Option 2 to compare
Grid operationAdditions
Full comparison by six criteria
Option 1 ↔ Option 2
First option
Second option
How to read the costs: the panels and inverters are listed as a kit on the invoice, without individual prices. Cable offers and examples for 30–35 m appear in the cable section; the final order length and price are unknown. “Cost items” lists additional expenditure. Panel, inverter, grid and battery compatibility requires datasheets and a checked design.
Principle diagram
Option 1 is shown.
Inverters by the panels: approximately 30 m of AC line to the house distribution board. This illustration shows the principle, not wiring connections or a final design.
Published labour rates and an illustrative labour-only calculation
Eramu Elekter: €35/h excluding VAT on weekdays (€43.40 at 24% VAT); Eesti Elektritööd: €49.60/h including VAT for contract work by one electrician and €60/h for small jobs. These are two companies' rates, not Xander's rate or a solar-station installation price.
Hours × rate only; excludes materials, mechanical installation, design, travel, measurements, inspection and grid fees. Earlier hour ranges are not backed by a work schedule.
What to request in comparable offers
Total cost including the previously purchased equipment and VAT; show the remaining payment separately.
Separate sums for A and B, then additions for the water heater and battery.
Part numbers, quantities, work scope, hours, checks, documents and warranty.
Work duration separately from grid and construction procedures.
Provisional conclusion: if export is available on acceptable terms, assess A first; otherwise check B and export-limitation compatibility. Assess additions according to separate needs. Decide after receiving offers and verifying the ordered devices.
Inverters: model to be confirmed
The 2022 invoice says “Growatt 3000 Tl1‑S”. No exact designation was found in the manufacturer's materials reviewed or in the Elektrilevi inverter list . Growatt 3000‑S is the main working hypothesis for three single-phase units, one per phase. Only the nameplates of all three inverters can confirm it.
3 × Growatt 3000‑S?3 kW AC each · datasheet and price inside
If this hypothesis is confirmed: each inverter is single-phase, with 3 kW AC output, maximum AC current 14.3 A, one MPPT and one string input, recommended panel capacity up to 3900 W, maximum DC voltage 550 V, start-up at 80 V, MPP range 70–550 V, maximum operating input current 13 A, and IP65 rating. Example strings of 8 + 8 + 9 panels give 3280 + 3280 + 3690 W STC, but voltage and current compatibility cannot be checked without the panel datasheet. Whether a DC isolator is built in depends on the exact version and must be checked on the devices.
Price of a new unit: for one unit — unconfirmed; for three units — unconfirmed. The invoice does not itemize the total kit price by inverter. Growatt Italia lists this model among Prodotti fuori catalogo. Shop listings show prices, but availability of three units, delivery to Estonia and comparable VAT have not been verified; multiplying an arbitrary unit price by three would therefore be misleading.
Important limitation: Neither a direct battery input nor a method for coordinating zero export across three 3000-S inverters has been confirmed. A battery needs a separate system architecture; option B remains conditional pending engineering review.
AC cable from the station to the house
Assumed layout: three single-phase inverters at the panels, one each on L1, L2 and L3; their outputs meet in an outdoor distribution board. One line of about 30 m runs to the main house board: L1/L2/L3/N/PE. This is a preliminary selection for discussion with an electrical specialist, not a purchase-ready specification.
Preliminary choice: copper 4×6/6 mm², 0.6/1 kV, with separate N and PE conductors. For a typical route entering the house, first check the version rated Cca‑s1,d1,a1. The measured route, diameter and condition of the existing conduit, indoor path, protection and actual inverter currents are still unknown.
Prysmian MCMK‑HF C‑PRo 4×6/6Cca · Ø≈17 mm · ask for a price per metre
Preferred candidate. Manufacturer part number 20204223, EAN 6410006020157. Four insulated 6 mm² copper cores for three phases and N, plus a concentric 6 mm² copper PE. Rated 0.6/1 kV, with PEX/XLPE insulation and a halogen-free sheath, for fixed installation indoors, outdoors and underground. Reaction-to-fire class Cca‑s1,d1,a1; outer diameter about 17 mm; minimum pulling bend radius 210 mm. The manufacturer's catalogue gives conductor resistance at 70 °C of 3.69 Ω/km and current ratings of 57 A in soil and 56 A in air under the stated table conditions; an underground conduit requires correction for the actual conditions.
Price:€11.54 shown for Voolu on Hinnavaatlus is an indicative listing. The sales unit, VAT, stock and availability of one continuous 30–35 m length have not been confirmed with the retailer. If that is the final price per metre, 30 m would provisionally cost €346.20 and 35 m €403.90, excluding delivery. Obtain a direct quotation before purchase.
Prysmian MCMK 4×6/6Eca · Ø≈18.5 mm · €9.66/m including VAT
Lower-cost candidate, subject to the route. Four 6 mm² copper cores plus a concentric protective conductor, rated 0.6/1 kV, with a PVC sheath and stated suitability for burial. The retailer lists an 18.5 mm diameter, conductor temperature up to 70 °C and Eca class. This is a different product from MCMK‑HF C‑PRo; its specifications and fire class cannot be assigned to the preferred cable.
Price in Tallinn:Emikson, Kadaka tee 44a — €7.79/m excluding VAT, approximately €9.66/m including 24% VAT; 30 m costs €289.80 and 35 m €338.10, excluding delivery. The listing says “Saadaval”, but a sufficient continuous length must be confirmed. Request the datasheet and DoP for the supplied batch: the retailer's insulation description needs checking against the manufacturer's documents.
NYY‑J 5×6 mm²Five separate cores · Ø≈18 mm · €7.71/m including VAT
Another type of underground line. Five separate 6 mm² copper cores for L1/L2/L3/N/PE, rated 0.6/1 kV, with a PVC sheath and stated suitability for soil and conduit. The retailer lists a diameter of about 18 mm, ELPAR or NKT as manufacturer, and Eca class. Obtain the exact manufacturer's part number and datasheet for the cable actually supplied: the designation NYY‑J 5×6 alone does not confirm its construction.
Price in Tallinn:Emikson, Kadaka tee 44a — €6.22/m excluding VAT, approximately €7.71/m including 24% VAT; 30 m costs €231.30 and 35 m €269.85, excluding delivery. The listing says “Saadaval”; confirm the continuous length and sales conditions. The same Eca limitation applies to the route inside the house.
Calculation and conditions for the final choice
Assuming 3 × 3 kW at 400 V and cos φ ≈ 1, phase current is about 13.0 A. For 30 m of Prysmian 4×6/6 with resistance 3.69 Ω/km at 70 °C, the line-to-line voltage rise under simultaneous balanced generation is about 2.49 V, or 0.62%. If the actual model is Growatt 3000‑S, its specified maximum output current is 14.3 A per unit: with three balanced phases, the estimated rise is about 2.74 V, or 0.69%; with only one phase generating, the phase-and-neutral path gives about 3.17 V at 230 V, or 1.38%. This estimates cable resistance only, excluding joints and voltage rise in the existing grid.
Before purchase, an electrical specialist must check the nameplates of all three inverters, whether one single-phase inverter per phase is permitted, the outdoor board design, protection against supply from both the house and the station, current-carrying capacity with conduit and soil corrections, fault loop and disconnection, PE and equipotential bonding, fire class along the indoor route, water in the conduit, internal diameter and bends. Purchase length = measured route + entries, rises, terminations and installation allowance; 30 and 35 m are price examples only. If the inverters move to the house, DC lines will be required along this route and this cable selection no longer applies.
Prices and availability were reviewed on 12 November 2026 from public retailer pages and a price catalogue. They may change; the displayed amounts are not an order, a commercial offer or the price of the kit already purchased.
Engineering checks before selection
10.25 kW DC is the arithmetic result of 25 × 410 W. About 9 kW AC is valid only if all three inverters are 3 kW units; their models remain unknown. Connecting one single-phase inverter per phase requires checks of the grid conditions, synchronization, protection and the documentation for the actual devices.
An illustrative 8 + 8 + 9 panel allocation gives 3280 + 3280 + 3690 W STC. This is not a compatibility check: panel datasheets are needed for Voc in cold conditions, Vmp across the temperature range, Isc, Imp, the number of inputs and the MPPT operating ranges.
The main working hypothesis is Growatt 3000-S. The manufacturer datasheet specifies 3 kW AC, recommended panel capacity up to 3900 W, maximum DC voltage 550 V, one MPPT and one string, with maximum operating input current 13 A. These are properties of the hypothesized model until the nameplates of all three units have been read. Datasheet 1000-S 1500-S 2000-S 3000-S (PDF · Italian).
For a nine-module string, check Voc at the design minimum temperature, Vmp in hot conditions, Isc and Imp against the datasheet of the panels actually supplied. With the inverters at the panels, the underground line to the house is AC; the preliminary 4×6/6 mm² selection and its conditions appear in the cable section. Compatibility of zero export and energy storage with this series has not been confirmed.
The AC/DC line choice depends on voltage drop and rise, current ratings, installation method, protection, PE and earthing. The design must specify surge protective devices at both ends of the 30 m line and, if the inverters are installed at the house, a DC isolator at the building entry. An existing underground conduit is not proof of suitability. A grid-tied inverter cannot supply an independent water heater when the grid fails unless a specific operating mode is provided; a battery requires a compatible architecture and a separate backup solution.
Legal and grid conditions
Laws and register entries were checked against primary sources on 12 November 2026 (Riigi Teataja, TARVIK, Elektrilevi). Applicability to this plot and the scope of work must be confirmed by the local authority, grid operator and a competent specialist.
Construction of a ground-mounted structure
For a separate ground-mounted electricity-generating structure below 100 kW, the table includes the row “Kuni 100 kW elektritootmisrajatis või energiasalvestusüksus”. Ehitusseadustik. Lisa 1. Tabel ehitusteatise, ehitusprojekti ja ehitusloa kohustuslikkuse kohta (PDF · Estonian; p. 5) requires, for construction, a building notice together with a design. The notice must be filed through ehitisregister at least 10 days before work begins (§ 36 lg 1–2). § 84² provides a rule for a solar installation below 100 kW: if the authority begins a review (§ 36(5)) but makes no decision within the period in § 36(6), construction may begin. This does not remove the notice or design requirement. The same row of Annex 1 includes energy-storage units: if the battery forms a separate structure, ask the local authority whether it also needs a notice and design. The authority determines classification for the particular plot. Saving on documentation does not remove applicable obligations.
Grid and zero export
Elektrisüsteemi toimimise võrgueeskiri § 22 (1¹) (the version effective from 1 September 2026): for a generating module up to 15 kW that does not export energy to the grid, a connection offer is issued within 30 days after a complete application. The general period in § 22(1) is also 30 days, but that provision allows a different period by agreement; § 22(1¹) has no such proviso. This is the period for an offer, not a deadline for completing a connection and not a promise of zero cost. Export, permitted export capacity, metering and connection point are subject to the operator's individual terms.
Electrical works and commissioning
Who may perform which work.Regulation No. 74, § 4 permits non-specialists only work at safe extra-low voltage (up to 50 V AC or 120 V DC) and simple actions such as replacing lamps and fuses. Mechanical assembly of the frame and modules is not electrical work. Connecting modules into strings, earthing and equipotential bonding of the frame, laying and connecting DC and AC lines, and work in the distribution board are electrical works: they must be performed by a company with an “Elektritööd” notice in the TTJA register; the contractor checks the result by measurement and documents it (§ 3). An 8–9-module string has hundreds of volts DC; DC lines remain live in daylight even if the inverter is off.
Inspection. A new or reconstructed installation is, by default, inspected before commissioning (Regulation No. 86, § 9). § 11(4) contains a limited exception for work in an existing, compliant low-voltage installation protected at no more than 35 A, with written confirmation from the contractor. It cannot automatically be extended to a new solar station. The main fuse rating determines the installation class (§ 3: up to and including 35 A is class III; above 35 A is class II), the possibility of applying the exception, and whether the contractor's register entry covers the work. The fuse rating is therefore a key question for the client. TTJA explanation.
Contractor. In the TTJA register (TARVIK, searched by registry code 17254839 on 12 November 2026), Xander Teenus OÜ has active notice TEL005216 “Elektritööd” from 27 September 2026: construction, maintenance and operation of class III electrical installations. If the main fuse exceeds 35 A, the scope of that entry must be checked with TTJA. Design work is not listed in the entry; responsibility for preparing the electrical design must be agreed separately. The contract and professional qualifications must distinguish mechanical installation, electrical work, design and independent inspection.
Responsibilities: the client provides information and chooses a solution; the contractor accepts an agreed scope and delivers work records; the electrical specialist calculates and documents the design; Elektrilevi sets the grid-connection terms; the local authority handles the applicable construction procedure. The owner and user are responsible for compliance and safe use of the electrical installation. TTJA.
Short list of missing information
A concise list of information needed to discuss the selected option. The site does not collect or save any data.
This is a short list for the first conversation. It does not replace the input data and site survey needed for design.
Glossary of technical terms
AC (alternating current) — alternating current used by the household electrical supply.
DC (direct current) — direct current generated by solar panels.
MPPT (maximum power point tracking) — tracking the solar panels' maximum power point.
The client's invoice and the cable calculation were reviewed but are not published because they contain order details. Prices and links were checked on 12 November 2026.
For discussion by Xander Teenus OÜ and the client. The diagrams show principles, not installation connections. Laws, register entries, model datasheets, prices and rates were checked on 12 November 2026; conditions for the specific plot and the required design scope remain unknown.