Marstek Saturn B2500-D

Name: Marstek Saturn B2500-D
Brand: Marstek
SKU: MST-B2500D
Author: JouleSpecs

Estimated price range

200–450 € ≈ $216–$486

An editorial estimate, not a selling price

JouleSpecs does not sell and does not show shop prices: check the price where you buy.

Sheet on the Marstek website →

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Data from official source

Sheet curated by JouleSpecs — We check every spec sheet against the manufacturer's own documentation: each value carries its source and the date we read it. Published Sept. 22, 2026 · Last updated Oct. 20, 2026 · Data verified Oct. 5, 2026

MARSTEK Saturn B2500-D is a battery that sits between the panels and the microinverter: the panels connect to two inputs on its body, and a separate output carries DC current to the microinverter, which converts it for the home grid. It has no inverter of its own, so it always needs to be paired with a microinverter, bought separately or in the same bundle.

More units can be chained: with a single-PV-input microinverter up to 2 units, while 3 or 4 units need microinverters with two or four PV inputs. The case has an IP65 protection rating and sits on the ground on the balcony, to be raised if the floor floods often. First setup goes through the app, over Bluetooth, to connect it to the home Wi-Fi.

01 · Verified data

Technical specifications

Cell chemistry LFP (lithium iron phosphate)

Feed-in limit 800 VA

Cost per kWh 267,41 €/kWh

official manufacturer list price — on nominal capacity

Round-trip efficiency Marstek does not state it.

where we looked

Standby consumption Marstek does not state it.

where we looked

Parameter	Value	Source
Weight	20.0 kg (44.1 lb)	manufacturer website
Nominal capacity	2.24 kWh	Declared by the brand
Cell chemistry	LFP (lithium iron phosphate)	Declared by the brand
Expandable	Yes	Declared by the brand
Maximum expanded capacity	8.96 kWh	Declared by the brand
Battery voltage	44.8 V	Declared by the brand
Feed-in limit	800 VA	Declared by the brand
Inverter included	No	Declared by the brand
Maximum solar input	1600 W	Declared by the brand
MPPT trackers	2	Declared by the brand
Rated cycles	6000 cicli	Declared by the brand
Warranty	10 anni	Declared by the brand
Ingress protection	IP65	Declared by the brand
Mounting	Floor standing	Declared by the brand
Minimum temperature	-10 °C	Declared by the brand
Maximum temperature	50 °C	Declared by the brand
App required for setup	Yes	Declared by the brand
Official list price	599 €	Declared by the brand
Depth of discharge	—	Not declared
Cell supplier	—	Not declared
Grid charging	—	Not declared
Maximum charge power	—	Not declared
Dynamic tariffs	—	Not declared
Backup power	—	Not declared
Backup output	—	Not declared
Switchover time	—	Not declared
Capacity at end of cycle life	—	Not declared
Guaranteed throughput	—	Not declared
Guaranteed remaining capacity	—	Not declared
Round-trip efficiency	—	Not declared
Standby consumption	—	Not declared
Cell heating	—	Not declared
Noise level	—	Not declared
Works without internet	—	Not declared
Local control	—	Not declared
Open protocols	—	Not declared
Home Assistant integration	—	Not declared
Where the data is hosted	—	Not declared
Remote updates	—	Not declared
Declared standards	—	Not declared
Battery passport	—	Not declared
Carbon footprint	—	Not declared
Recycled content	—	Not declared

Which documents this page rests on

SATURN-C B2500 User Manual compressed 37 rows of the table · file hosted on cdn.shopify.com
User Manual of MI0800W-0208 1 row of the table · file hosted on cdn.shopify.com

The rest of the data comes from 2 pages on the manufacturer's site, cited row by row in the table above.

A manual or a datasheet counts as a source even when the original file is hosted elsewhere: what matters is the document, not the server. Where that happens, it is stated above.

02 · The numbers

What it really costs

Cost per kWh 267.410 €/kWh official manufacturer list price — on nominal capacity

How we worked it out

price: 599
nominal capacity: 2.240

Battery life cycles 3650 cycles warranty years

the manufacturer does not state the guaranteed total energy throughput, which for heavy users is often the limit that runs out first

How we worked it out

stated cycles: 6000
warranty years: 3650

Cost of stored energy 0.073 €/kWh warranty years

the manufacturer does not state the guaranteed total energy throughput, which for heavy users is often the limit that runs out first
on nominal capacity: the manufacturer does not state the usable figure, so the real cost is higher
without conversion losses, which the manufacturer does not state: the real cost is higher

How we worked it out

price: 599
nominal capacity: 2.240
battery life cycles: 3650
round-trip efficiency: 100
energy delivered over the whole life: 8176

Energy density 112 Wh/kg

on nominal capacity: the manufacturer does not state the usable figure, so the true number is lower

How we worked it out

nominal capacity: 2.240
weight: 20

These numbers are calculated, not stated: they have no source to cite, they have a formula you can redo. The price used is the manufacturer's list price, which is stable and the same in every country — not a shop's price on the day.

03 · Summary

Pros and cons

In favour

Several units can be chained: up to 2 with a single-PV-input microinverter, 3 or 4 with microinverters with two or four PV inputs.
The IP65 protection rating allows keeping it on the balcony, outdoors.
Two independent solar inputs: two panels with different orientations don't hold each other back.
It slots in between the panels and the microinverter of a balcony system.

Worth knowing

It has no inverter of its own: a paired microinverter is needed, bought separately or in a bundle.
First setup has to go through the app, over Bluetooth and Wi-Fi.
If the balcony floods often, it has to be raised off the floor.

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