How to Read a Solar Inverter Datasheet: A Buyer’s Field Guide

Most inverter comparisons start with maximum efficiency. That number is easy to quote and hard to use. Before it means anything, the model has to fit the array, the grid connection and the site. A datasheet is best read as a set of operating boundaries: the buyer's job is to find the limit that decides the selection, then confirm it for the exact model and market.

This is the second guide in our inverter series. The first covered the architecture decision — on-grid, hybrid or off-grid (read it here). This guide covers the document itself: what each field means, which limits usually bind, and which fields apply only to on-grid, hybrid or off-grid units.

Every model-specific value below is taken from a manufacturer datasheet. Each retained value is recorded in the source register with the document SHA-256, revision date, PDF page, model column, original field name and unit. Nothing in this guide is taken from the website's own product copy, and no value is presented as a general capability of "all inverters".

1. Fix the model column before reading any number

A datasheet often covers a family, not a single unit. The header row names the exact models; each column is a separate configuration.

• The Growatt MOD 10–15KTL3-X datasheet covers five models (MOD 10K, 11K, 12K, 13K and 15K) across two pages.
• The Deye SUN-18/20/22/23/25K-G05 page puts five models in one table.
• The Solis S5-GR3P datasheet covers twelve models from 3K to 20K in a single table.

Read the column heading first, then the row. A value placed in a shared cell applies to every model in the family; a value placed under one model applies only to that column. If the model suffix differs — LV, -X, -AM8, G05, G04 — treat it as a different product until the datasheet says otherwise.

Footnotes are part of the specification, not small print. A footnote may carry a region-specific limit or condition that applies to one model column only. A buyer who reads only the table can carry the wrong limit into the design.

2. DC input: the three limits that decide string feasibility

2.1 The DC power figure is a recommendation or a limit — read the label

The DC-side power figure is not written the same way on every datasheet. Some manufacturers publish "Max. recommended PV power (for module STC)"; others publish "Max. DC input power" or "Max. PV input power". The label matters.

• "Recommended" describes the module capacity the manufacturer expects at STC. It is a sizing recommendation, not necessarily a hard input limit for every model.
• "Maximum DC input power" is written as a limit. It should be treated as one, subject to the footnotes and conditions in the same document.

Both are DC-side figures, and neither is the inverter's AC rating:

• Growatt MOD 10KTL3-X: 15,000 W recommended PV power against 10,000 W AC nominal power.
• Deye SUN-15K-G05: 19.5 kW maximum DC input power against 15 kW rated output.
• Deye SUN-60K-G: 78 kW maximum PV input power against 60 kW rated AC output.
• Solis S5-GR3P10K: 15 kW recommended maximum PV power against 10 kW rated output.

The relationship between the two numbers is visible in the datasheet, but the label decides how it may be used. A recommended figure informs the array design; a maximum figure constrains it. Whether a particular DC/AC relationship is commercially right depends on the project's load profile, export limits and the value of clipped energy — questions that sit outside the datasheet.

If the field is missing, do not assume a value from a similar model. Ask the manufacturer whether the model has a recommended figure, a hard limit, or both, and record the answer with the datasheet version.

2.2 Maximum DC voltage is a hard limit

"Max. DC voltage" is the highest open-circuit voltage the DC side may see. It is not a nominal operating value.

• Growatt MOD 10KTL3-X: 1,100 V.
• Solis S5-GR3P10K: 1,100 V.
• Deye SUN-15K-G05: 1,000 V.
• Deye SUN-18K-G05: 1,100 V.

The string layout must keep the module's temperature-corrected open-circuit voltage below this figure at the coldest expected condition. That calculation depends on the module, the minimum site temperature and the design margin. This guide does not provide a fixed string-sizing formula; the check belongs to a qualified designer using the actual module datasheet and the inverter's limit.

2.3 Start voltage and MPPT range are different windows

A datasheet normally gives three voltage figures: start voltage, nominal voltage and MPPT voltage range. They answer three different questions.

• Start voltage is the DC voltage at which the unit is specified to begin its start-up sequence. It is not, by itself, a guarantee of output: the unit also has to pass its internal checks and see an acceptable grid or load condition. The MOD 10KTL3-X lists 160 V; the Deye SUN-15K-G05 lists 250 V; the Solis S5-GR3P10K lists 180 V.
• MPPT voltage range is where the inverter tracks the array's maximum power point. The MOD 10KTL3-X window is 140–1,000 V; the Solis S5-GR3P10K is 160–1,000 V; the Deye SUN-15K-G05 is 200–850 V.
• Nominal voltage is a reference point for design, not a narrower operating limit.

A wide MPPT window gives the designer more room; a narrow one constrains it. The Deye SUN-15K/17K-G05 page shows a 200–850 V MPPT window, while the SUN-18–25K-G05 page shows 200–1,000 V. Two pages from the same manufacturer, two different design envelopes — which is why the exact model column matters.

If a value or a row label looks inconsistent — for example, a nominal voltage outside the MPPT range — do not correct it yourself and do not infer the intended value from a similar model. Ask the manufacturer for written confirmation, and use that confirmation, not a guess, in the design file.

3. Current limits: identify the input, string and MPPT scope

The DC current rows decide how many strings can be connected and where. Before comparing numbers, identify the scope of the row: current may be published per input, per string, per MPP tracker or for the whole unit, and the unit may be A, mA or a current plus a voltage condition. The label — not the position in the table — tells you which limit applies.

• Growatt MOD 10KTL3-X: two MPP trackers, one string per tracker, 13 A maximum input current and 16 A maximum short-circuit current per tracker.
• Growatt MID 15KTL3-X: two trackers, two strings per tracker, 27 A input and 33.8 A short-circuit current per tracker.
• Growatt MAX 50–80KTL3 LV: six or seven trackers, two strings per tracker, 26 A maximum input current and 32 A maximum short-circuit current per tracker.
• Deye SUN-15K-G05: two trackers, a 1+2 string arrangement, 13+26 A input and 19.5+39 A short-circuit current.
• Solis S5-GR3P10–20K: two trackers, up to four strings, 32 A input and 40 A short-circuit current per tracker.

Three practical consequences follow. First, the number of strings is limited by the tracker, not by the total DC input. Second, the short-circuit current is a protection limit and should be treated separately from the operating current. Third, an asymmetric arrangement — such as 1+2 strings on the Deye SUN-15K — means the two trackers do not have the same capacity; the layout has to respect the difference. In every case, confirm whether the figure is per tracker or for the whole unit before comparing it with a string calculation.

4. AC output: kW, kVA, phase and grid window

The AC side of the datasheet answers a different set of questions: what the unit delivers continuously, what it can deliver briefly, how it connects, and which grid it is built for.

4.1 Rated power and maximum apparent power

"Rated AC output power" is the continuous active power rating. Datasheets then use one of two different ceilings: "Max. AC apparent power" in VA, or "Max. active power" in kW. They are not the same field and should not be compared as if they were.

• Growatt MOD 10KTL3-X: 10,000 W rated, 11,000 VA maximum apparent.
• Growatt MAX 50KTL3 LV: 50,000 W rated, 55,500 VA maximum apparent.
• Deye SUN-15K-G05: 15 kW rated active power, 16.5 kW maximum active power.

The apparent-power gap matters for protection and cable sizing. For a 50 kW unit rated at 55,500 VA apparent power, the AC current delivered at the terminals can be higher than the kW rating alone suggests, especially at a power factor below unity. That current is an output characteristic of the inverter; it is not the same as the current drawn by the site load. Where a datasheet publishes a maximum active power instead, that figure is an active-power ceiling and does not by itself give the apparent current at the terminals.

4.2 Phase, voltage and frequency

The connection type is not a detail to be settled later.

• The Growatt MIN 2500–6000TL-X is a single-phase family with a 230 V nominal AC voltage (180–280 V range in the datasheet).
• The Growatt MOD 10–15KTL3-X is three-phase, with 220/380 V or 230/400 V nominal and a 340–440 V range.
• The Solis S5-GR3P10–20K is three-phase, 3/N/PE, 220/380 V or 230/400 V.
• The Deye SUN-60K-G is 3L/N/PE, 380 V or 400 V nominal, with a 0.85Un–1.1Un range.

Frequency follows the market: 50/60 Hz with a window such as 45–55 Hz or 55–65 Hz. The datasheet's window is the inverter's capability, not the grid code's requirement. The destination market's grid code can be narrower, and the certificate — not the datasheet — is the evidence for that market.

4.3 Maximum output current depends on voltage

Some datasheets list more than one output current for the same model because the current changes with the grid voltage. When that is the case, cable, breaker and switchgear selection should use the value at the project's actual voltage, not the more convenient number. Where the datasheet does not label which value belongs to which voltage, ask the manufacturer to confirm before the protection study. The current in this row is the inverter's AC output current, not the current consumed by the load.

5. Efficiency: maximum versus weighted

"Max. efficiency" is the best single operating point. "European efficiency" (or another weighted efficiency) is a part-load average, and it is usually the more useful number for a commercial or industrial system that spends much of the day below full power.

• Growatt MOD 10KTL3-X: 98.6% maximum, 98.1% European efficiency.
• Solis S5-GR3P10K: 98.6% maximum, 98.0% EU efficiency.
• Deye SUN-15K-G05: 98.5% maximum, 97.5% Euro efficiency.
• Deye SUN-120K-G01P3: 98.8% maximum, 98.2% Euro efficiency.

The gap between the two figures is not a defect; it describes the shape of the efficiency curve. A buyer comparing two models should compare the weighted figure for the expected load profile. Weighted efficiency is a benchmark under a defined weighting, not the project's annual energy yield: it cannot be equated directly with bill savings or revenue. Converting an efficiency percentage into annual energy requires a site-specific simulation with the actual irradiance, temperature and load profile.

MPPT efficiency is a third, separate figure. It describes how closely the tracker follows the array's maximum power point, and it is not comparable with conversion efficiency.

6. Temperature derating and IP rating

Datasheet power ratings are stated under defined conditions. Temperature derating tells you what happens outside them.

• Deye SUN-15K/17K-G05: operating range −25 to +65 °C, with derating above +45 °C.
• Deye SUN-60K-G: −25 to +60 °C, with derating above +45 °C.
• Growatt MOD 10KTL3-X: −25 to +60 °C; the datasheet does not publish a derating threshold.

A unit that is rated at 60 kW at a reference temperature may deliver less at a site where the ambient temperature sits above the derating point for several hours a day. The design should use the derated output at the site's design ambient, not the headline rating.

The IP rating describes the enclosure's protection against dust and water. It is not a statement that the unit can be installed anywhere outdoors.

• Growatt MOD 10KTL3-X: IP66.
• Growatt MID 15KTL3-X: IP65.
• Growatt MIN 2500–6000TL-X: IP65.
• Growatt MAX 50KTL3 LV: IP65.
• Deye SUN-15K-G05 and SUN-60K-G: IP65.

Installation position, shading, salt exposure and cooling clearance are separate requirements in the installation manual. The IP number does not replace them.

7. Hybrid-only fields: battery, charge/discharge and backup

A hybrid datasheet has to answer questions that do not exist on an on-grid unit. The relevant fields are:

• Battery voltage window and supported battery chemistry. A battery outside the window is not supported, regardless of its capacity.
• Maximum charge and discharge current or power. This limits how fast the battery can absorb or deliver energy.
• Backup output rating. The backed-up load is limited by the backup output, not by the total inverter rating.
• Transfer behaviour and backup configuration. Whether the unit can form a grid, how fast it transfers, and which loads are connected to the backup port.
• Generator or ATS input, where the model provides one.

A product catalogue or a family brochure is not a substitute for a model datasheet. A catalogue page may show a headline power rating and a PV operating window, but it usually does not publish the battery voltage window, the charge and discharge limits, the backup output rating or the transfer behaviour. For a hybrid project, request those fields for the exact model before the battery and backup loads are designed.

8. Off-grid-only fields

An off-grid unit is specified by different limits again: continuous and surge output, battery charger capability, generator input, parallel capability and idle consumption. A catalogue may give a continuous and a surge headline, but not necessarily the surge duration, the charger current or the generator interface. Those must be confirmed from the model datasheet, including the conditions under which the surge rating applies.

9. Certificates, warranty and the document itself

Three things are often confused at the end of a datasheet:

• Technical specifications describe what the unit does.
• Certificates describe which standard, revision and scope an independent body has assessed for a specific market. The datasheet may list standards; the certificate is the evidence. Ask for the certificate and check that the model and market match.
• Warranty terms describe the commercial remedy, exclusions and claim process. A datasheet line such as "5 years / 10 years optional" is a product summary, not the warranty contract.

The document itself also needs to be controlled. Manufacturer datasheets commonly end with "specifications subject to change without notice". Record the file name, revision date and page used for the quotation, and attach that version to the purchase order. If a later revision changes a limit, the project file should show which version was priced.

10. A twelve-point datasheet review

Before a quotation request, confirm each of the following for the exact model column:

1. Full model name and suffix, including any regional variant.
2. Maximum recommended PV power or maximum DC input power — whichever label the datasheet uses — and the resulting DC/AC relationship.
3. Maximum DC voltage and the temperature-corrected string voltage check.
4. Start voltage and MPPT voltage range.
5. Number of MPP trackers and strings per tracker.
6. Maximum input current and maximum short-circuit current, with the unit and scope confirmed (per input, per string, per tracker or whole unit).
7. Rated AC output power and the published maximum — apparent power (kVA) or active power (kW), as labelled.
8. Phase, nominal voltage, voltage range and frequency window.
9. Maximum output current at the project's voltage.
10. Maximum and weighted efficiency.
11. Derating temperature, IP rating, altitude and cooling requirements.
12. Certificate scope and warranty terms, as separate documents.

For a hybrid or off-grid model, add the battery voltage window, charge/discharge limits, backup or surge rating, and transfer or generator interface.

11. How to obtain and confirm the correct version

A datasheet is only useful if it is the right document for the exact model and the revision that will be supplied. Before using it for design or a purchase order:

• Ask for the datasheet for the full model name and suffix, not the family brochure or a catalogue page.
• Confirm the document type: a datasheet, a certificate and a product catalogue answer different questions. A certificate is evidence of a standard and scope; it is not an operating table.
• Record the revision date and page used for the quotation, and attach that version to the purchase order.
• Where a value or row label is inconsistent, ask the manufacturer for written confirmation and use that confirmation in the design file. Do not correct the document yourself.
• For hybrid or off-grid models, ask specifically for the battery compatibility list, charge/discharge table and backup output table. If those are not published, they should be provided in writing for the exact model.
• Keep the confirmed version with the project file so that a later revision can be compared with the one that was priced.

If a supplier cannot provide the document for the exact model, treat the missing field as unresolved rather than filling it with a value from a similar product.

12. Request a quotation

If you have the model shortlist and the project conditions, send them through the contact page. Include the destination market, phase and voltage, required AC power, backup or off-grid requirements, and the battery specification where relevant. We will quote against the published models and the datasheet version current at the time of quotation.

The models used as examples in this guide are published here: Growatt MOD 10–15KTL3-X, Growatt MID 15–25KTL3-X, Growatt MAX 50–80KTL3-LV, Growatt MIN 2500–6000TL-X, Deye SUN-15/17K-G05, Deye SUN-18/20/25K-G05, Solis S5-GR3P 10–20K, OCT-S-I-6KW and BIN-S-I-6KW.

For the architecture decision behind this checklist, read On-Grid vs Hybrid vs Off-Grid Inverters. For the published inverter range, start at Solar Inverters.