New Fogstar 15.5kWh upright solution

vaugi · 2023-11-19T11:17:06Z

Just noticed Fogstar have a new upright solution (coming soon). Given that it's Grade A cells, battery heater, cell balancer and 8yr warranty at £2500 incl VAT, is there much point DIYing with a Seplos anymore (at least for single bank solutions)?

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Batpred

(@batpred)

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Joined: 10 months ago

Posts: 90

17/10/2025 5:30 pm

Posted by: @transparent

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I think there will be only ONE oscillator in the inverter which provides 50Hz when the grid is down.
You can't have multiple sources for the same reference frequency!

My suggestion would be to focus on the function. The goal of that oscillator is ultimately to set the 50Hz for the AC outputs that are separate from the grid.

Posted by: @transparent

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If you receive email messages from Solis tech-support staff stating that there are oscillators (plural), then I hope you'd
take a snapshot and post the images here.
Who says what, and in what context, is important.

I would, but my focus is to make sure that my current and future 'use cases' will be supported, potential value of external ATS, extra loads, etc.

As an example, a simple config change and now the Solis also boots from grid AC, which stops the battery being a single point of failure.

When I get a chance to test that 4ms failover from blackouts I will report.

Posted by: @transparent

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I don't like that because it leaves you without any 30mA trip protection on the external supply cable.

Yes, but least the other inverter related circuits can be protected. Hybrid inverter installs without full 30ma protection will not stand out on many "fuseboards".

Thinking ahead, when connecting PV to this Solis inverter, there seem to be two main options:

- PV can be connected to DC ports directly via MPPT. There are two sets, in our case we will never need more.

- a small inverter could be used to connect PV and output AC to the smart port of this inverter.

From an efficiency viewpoint, what would currently be the best way to do it?

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Transparent

(@transparent)

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Posts: 2599

17/10/2025 7:26 pm

Posted by: @batpred

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As an example, a simple config change and now the Solis also boots from grid AC, which stops the battery being a single point of failure.

From my experience with inverters from different Far East manufacturers, starting the inverter can be affected by the preferences you configure, and which combination is currently available.

You have three potential inputs, plus a "smart port".
Most hybrid inverters allow you configure the preferential order in which those inputs will be chosen to supply the output(s).

You can sometimes find that the firmware 'refuses' to overlook an input which is currently not available.
or, perhaps worse, is that firmware won't switch back to your chosen input priority-list after it completes a timed event.

I've often encountered inverters which stubbornly continue supplying the 'house load' directly from the grid once they've recharged the battery overnight at cheap rate.
Aagh!

Posted by: @batpred

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... when connecting PV to this Solis inverter, there seem to be two main options:

- PV can be connected to DC ports directly via MPPT. There are two sets, in our case we will never need more.

- a small inverter could be used to connect PV and output AC to the smart port of this inverter.

Use both inbuilt MPPT ports.

Don't attempt the second option.

Whatever 'smart' functionality is available via that port, you don't want to be putting two inverters in series.

Try thinking of that smart-port as if it's where you connect a generator on a farm in the Australian outback!

Save energy... recycle electrons!

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