General

Adding Inverters to Your Catalogue

If panels are the foundation of a quote, the inverter is the brain. It decides how solar DC becomes usable AC, how panels are grouped electrically, and (for hybrids) how a battery charges and discharges. Inverters are the most technical product you will set up in Powerlily, because the design tool leans on their specs to string your arrays. Get the numbers right and the auto stringer does the hard work for you. Get them wrong, or leave them blank, and the tool either refuses to string or strings conservatively.

This article covers the three inverter types, every field, and exactly which values the auto stringer needs.

The three types of inverter

Powerlily supports three inverter types, and the form changes depending on which you pick. You set the type at the top of the inverter form.

String inverter. A central inverter wired to one or more strings of panels. This is the type with the most electrical specifications to fill in, because the design tool has to work out how many panels go in each string and how they connect to the inverter's inputs.

Microinverter. One small inverter mounted at each panel, converting DC to AC right at the roof. Micros do not get strung, so instead of MPPT and voltage specs you tell Powerlily how many panels each unit can service (1 to 4). The design tool then places one micro per panel group automatically.

Hybrid inverter. A string inverter with a battery-management stage built in. It carries the full set of string electrical specs (so it strings exactly like a string inverter) plus battery charge and discharge specs. Hybrids are the key piece for DC-coupled storage. For how hybrids interact with batteries and the BESS validation card, see the companion article on hybrid inverters and AC/DC coupled storage.

The three ways to add an inverter

These work the same as panels:

Add from the Powerlily library. From the Inverters page, click Add Product to open the picker. Search, filter by brand, and click the plus to copy a ready-made inverter, with all its electrical specs already filled in, into your catalogue. This is the fastest route and the safest, because library inverters arrive string-ready.
Extract from a spec sheet with Pericles. On the New Inverter screen, Pericles (our AI spec sheet reader, available on Pro accounts) takes the manufacturer datasheet as a PDF or image and fills the form for you: type, rated power, efficiency, MPPT count, voltage windows, current limits, and battery specs for hybrids. Always review the values before saving, since inverter datasheets vary widely in how they label these fields.
Create one manually. Fill the form field by field. Each field saves as you change it, so there is no single save button.

If you cannot find an inverter in the library, email support@powerlily.io and we will add it.

The fields, explained

Basics (all types)

Field	What it means
Name	What the inverter is called across the app and on quotes. Required.
Brand and Model	Manufacturer and model number. Brand drives the logo on listings and proposals.
Inverter Type	String, Micro, or Hybrid. Determines which specialised fields appear.
Rated AC Power Output	The inverter's nameplate AC output, in watts. This is the headline number and is required.
Nominal AC Voltage	The grid connection voltage: 208, 240, or 480 V.
Efficiency	Peak conversion efficiency, as a percentage.
Warranty	Warranty length in years.
Value	Your cost per unit. Drives quote pricing. Required (Pericles defaults this to $0).
Height, Width, Depth, Weight	Physical dimensions and weight, for documentation.
Show in Catalogue	If unchecked, the inverter is hidden from your catalogue but can still be used in designs and on quotes.

Microinverter field

Field	What it means
Panels Serviced	How many panels one microinverter supports (1 to 4). The design tool uses this to work out how many micros a layout needs.

String and hybrid electrical specifications

This is the section that powers stringing. Every field here feeds the auto stringer, so precision matters.

Field	What it means
Number of MPPTs	How many independent Maximum Power Point Trackers the inverter has. Each MPPT optimises its own string or group of strings separately.
Strings per MPPT	How many string inputs each MPPT channel accepts.
Max DC Power	The largest total DC input the inverter will accept across all MPPTs.
Max DC Power per MPPT	The DC power ceiling for a single MPPT channel.
Max Voc Input	The highest open-circuit voltage the inverter can safely see on its DC input. This is the hard limit a cold-weather string must never exceed.
Min Input Voltage	The minimum DC voltage the inverter needs to start operating.
Min MPPT Voltage and Max MPPT Voltage	The voltage window in which the MPPT can actually track maximum power. Strings should sit inside this window across the temperature range.
Max Input Current	The maximum operating DC current per MPPT.
Max Short Circuit Current	The maximum short-circuit current the DC input can handle.

Hybrid battery specifications

Shown only for hybrids:

Field	What it means
Max Battery Charge and Max Battery Discharge	How fast the hybrid can charge and discharge a paired battery, in kW. For DC-coupled batteries these often set the ceiling for the whole storage system.
Integrated Battery Storage (optional)	Total capacity, usable energy, and depth of discharge, but only for all-in-one hybrids that ship with a battery in the same enclosure (Tesla Powerwall 3, EP Cube, Sigenergy SigenStor). Leave blank for hybrids that pair with a separate battery.

How the auto stringer uses these values

When you string an array in the 3D design tool, Powerlily does not just divide panels into equal groups. It runs the panel's electrical nameplate values against the inverter's limits to find a configuration that is both safe and productive. It factors in:

Cold-weather voltage. Panel Voc rises as temperature drops. The stringer projects worst-case cold voltage from the panel's Voc and its temperature coefficient, then makes sure the string stays under the inverter's Max Voc Input. This sets the maximum number of panels per string.
Operating voltage window. It checks that the string voltage stays inside Min MPPT Voltage and Max MPPT Voltage so the inverter can actually track the array, which sets the minimum string length.
Current limits. Panel Isc and Impp are checked against Max Input Current and Max Short Circuit Current per MPPT.
Power limits. Total array DC is checked against Max DC Power, and each MPPT's share against Max DC Power per MPPT.
MPPT topology. The stringer respects Number of MPPTs and Strings per MPPT when distributing strings, and it accounts for MPPT-level losses when strings on the same tracker are not perfectly matched. This is why uneven string lengths on one MPPT can cost production: the tool models that loss rather than ignoring it.

Because the stringer accounts for those MPPT losses, the specs you enter need to be accurate. Rounded or guessed numbers lead to strings that look fine on paper but underperform in the model. The upside is that the auto stringer will not produce an unsafe design: if no valid configuration exists (for example the panel and inverter voltages are incompatible), it tells you rather than stringing something that would overvoltage the inverter in winter.

Quick reference: what each type needs

Microinverter: Rated AC Power, Value, and Panels Serviced. No stringing fields.
String inverter: the basics plus the full String Inverter Electrical Specifications section, or the design tool cannot string the array.
Hybrid: everything a string inverter needs, plus the battery charge and discharge specs, plus integrated storage only if it is an all-in-one unit.

Tip: If the design tool will not string an array built on a string or hybrid inverter, open the inverter and check the electrical section. A missing Max Voc Input, MPPT voltage window, or MPPT count is almost always the cause. Library inverters and Pericles-extracted inverters supply these automatically, so reach for those before building one by hand.

Building Your Panel Catalogue. The panel side of the stringing equation.
Adding Batteries to Your Catalogue. How hybrids pair with DC-coupled storage.
Understanding Hybrid Inverters and AC/DC Coupled Storage. The concept behind hybrids and how batteries connect.
Pericles, Your AI Assistant. The spec sheet extractor that fills inverters in for you.