Batteries are the most demanding product to set up in Powerlily, because their specs feed two different engines that each have their own requirements. The single-line diagram (SLD) generator needs the electrical numbers to draw and size the battery circuit. The battery analysis needs the energy and power numbers to model backup time and savings. A battery can sit happily in your catalogue and still come up short for one engine or the other, so it pays to understand which field does what.
There is also a concept that sits above all the fields and decides how the whole battery behaves on a quote: AC coupling versus DC coupling. Get that one switch right and everything downstream follows. For the full picture of how coupling interacts with hybrid inverters and the BESS validation card, see the companion article on hybrid inverters and AC/DC coupled storage. This article focuses on the battery record itself.
The one field that changes everything: AC Coupled
At the top of the battery form is a single switch, AC Coupled, labelled "Battery includes its own inverter." It is the most important field on the form.
- AC Coupled on. The battery has its own onboard inverter. It connects to the home's AC bus and works on its own. It does not need a hybrid inverter, and on a quote it is marked Built-in and ready to go. Its charge and discharge rates come straight from its own specs.
- AC Coupled off (DC-coupled). The battery is a bare pack with no inverter. It needs a hybrid inverter to function. On a quote Powerlily tries to pair it with a hybrid automatically. If one is present it shows as Paired (and the hybrid sets the charge and discharge ceilings). If no hybrid is on the quote, it shows Pairing needed in red, and the battery analysis cannot run until that is resolved.
This is why the same battery can produce a complete analysis on one quote and a "pairings needed" warning on another. The switch describes the hardware. The quote decides whether the supporting hybrid is present.
The three ways to add a battery
These mirror panels and inverters:
- Add from the Powerlily library. From the Batteries page, click Add Product, search, filter by brand, and click the plus to copy a ready-made battery with its specs filled in. Fastest and safest route.
- Extract from a spec sheet with Pericles. On the New Battery screen, Pericles (our AI spec sheet reader, available on Pro accounts) reads the manufacturer datasheet (PDF or image) and fills the form: capacity, usable energy, depth of discharge, efficiency, power ratings, and voltage range. Always review before saving, since battery datasheets label these specs in many different ways.
- Create one manually. Fill the form field by field. Each field saves as you change it.
If a battery is missing from the library, email support@powerlily.io and we will add it.
The fields, explained
Basics
Field |
What it means |
|---|---|
Name |
What the battery is called across the app and on quotes. Required. |
Brand and Model |
Manufacturer and model number. Brand drives the logo on listings and proposals. |
Battery Type |
Chemistry: Lithium Iron Phosphate (LFP), Lithium Ion, NMC, Lead Acid, Sodium Ion, or Other. |
Price |
Your cost per unit. Drives quote pricing. Required. |
Warranty |
Warranty length in years. |
Height, Width, Depth, Weight |
Physical dimensions and weight, for documentation. |
Show in Catalogue |
If unchecked, the battery is hidden from your catalogue but can still be used on quotes. |
Energy and power specs
These are the numbers the two engines care about. The last column notes which engine each one feeds.
Field |
What it means |
Used by |
|---|---|---|
Total Capacity (kWh) |
Nameplate energy capacity. |
Analysis + SLD |
Usable Energy (kWh) |
Energy available after depth-of-discharge limits. |
Analysis + SLD |
Depth of Discharge (%) |
Share of total capacity that can be safely drained. |
Analysis |
Efficiency (%) |
Round-trip efficiency (energy out divided by energy in). |
Analysis |
Continuous Power Rating, Charge (kVA) |
Maximum continuous charging power. |
Analysis |
Continuous Power Rating, Discharge (kVA) |
Maximum continuous discharging power. |
Analysis + SLD |
Rated Continuous Output Current (A) |
Maximum continuous output current. |
SLD |
Maximum DC Voltage / Minimum DC Voltage (V) |
The battery's DC bus voltage range. |
SLD |
OCPD (A) |
Recommended overcurrent protection (breaker) rating. |
Documentation |
Peak Power Rating (kVA) / Peak Output Current (A, ~10 s) |
Short-duration surge ratings. |
Documentation |
What the battery analysis needs
The battery analysis simulates an outage across four seasons and calculates energy savings. It is forgiving: most fields fall back to a sensible estimate rather than failing. But the closer your fields are to the datasheet, the more accurate the customer-facing numbers in the proposal.
Here is exactly how it resolves each input:
- Usable energy. Uses Usable Energy if present. If blank, it falls back to Total Capacity × Depth of Discharge. If both of those are missing it has no energy to model, so at minimum set capacity and DoD.
- Charge rate. Uses Continuous Power Rating (Charge). If blank, falls back to the discharge rating, then to half of total capacity.
- Discharge rate. Uses Continuous Power Rating (Discharge). If blank, falls back to half of total capacity.
- Round-trip efficiency. Uses Efficiency. If blank, defaults to 90 percent. For DC-coupled batteries it stacks this with the paired hybrid inverter's efficiency, since the energy passes through both.
For a DC-coupled battery, remember the charge and discharge rates the analysis uses come from the paired hybrid inverter, not the battery itself. So an accurate hybrid record matters just as much as the battery record. This is the link back to the inverter article: a DC battery with a poorly specified hybrid produces a poorly modelled backup time.
The takeaway for analysis: at a bare minimum the analysis needs an energy figure (Usable Energy, or Total Capacity plus Depth of Discharge). Fill in Efficiency and the two Continuous Power Ratings as well, and the backup-time and savings numbers stop relying on fallbacks.
What the SLD generator needs
The SLD generator is stricter, because it is drawing an electrical diagram that has to size conductors and a disconnect. It reads:
- AC Coupled, to decide whether the battery self-inverts or connects through a hybrid. This determines how the battery is wired on the diagram.
- Rated Continuous Output Current, to size the battery circuit conductors and disconnect. If this is blank, it falls back to the Continuous Power Rating (Discharge) to estimate the circuit.
- Maximum DC Voltage and Minimum DC Voltage, to label the battery's DC voltage on the diagram (it uses the midpoint of the two).
- Total Capacity or Usable Energy, for the system kWh shown on the diagram.
If the SLD is missing the battery's voltage range or output current, the battery block will be incomplete or under-specified. Fill in the min and max DC voltage and the rated continuous output current to get a clean, code-ready diagram.
Quick reference: minimum viable battery
- To price it on a quote: Name and Price.
- To run the battery analysis: an energy figure (Usable Energy, or Total Capacity plus Depth of Discharge), plus Efficiency and the Continuous Power Ratings for accuracy. For DC-coupled batteries, a properly specified paired hybrid.
- To generate a clean SLD: the AC Coupled switch set correctly, Rated Continuous Output Current, Min and Max DC Voltage, and a capacity figure.
- Above all: set AC Coupled correctly. It decides whether the battery needs a hybrid, how the analysis sources its rates, and how the SLD wires it.
Tip: If a quote shows "battery pairings needed," the battery is DC-coupled with no hybrid inverter present. Either add a hybrid inverter to the quote or switch to an AC-coupled battery. If the analysis runs but the numbers look thin, open the battery and check Usable Energy, Efficiency, and the power ratings before blaming the model.
Related articles
- Adding Inverters to Your Catalogue. Hybrids set the charge and discharge rates for DC-coupled batteries.
- Understanding Hybrid Inverters and AC/DC Coupled Storage. AC versus DC coupling and the BESS validation card.
- Utilities, Rates, and Consumption. Where the savings side of the battery analysis comes from.
- Pericles, Your AI Assistant. The spec sheet extractor that fills batteries in for you.
