SMA increased self-consumption with backup power configuration

Harakas

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Nov 24, 2021
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Hey!

I have installed an SMA Sunny Island 8 running in battery backup with increased self-consumption mode with a Sunny Home Manager 2.0 that acts as
an energy meter. It's dead winter here at the moment with practically no sun available so I'm using grid power basically. But there are complications related to my limited grid connection: I can only pull 10A from the grid. Hence my questions:
  1. Can you configure the sunny island (SI) to charge batteries from the grid only when there are no other loads connected (to limit grid pull usage to 10A). I can configure it to do timed charging but it would be way more convenient to make it also dependant on available power -- SI has this information from the SHM. I figure that if I reconfigured the network into off-grid mode the SI would basically do this automatically (where grid is connected as a generator).
  2. Can you configure the SI to only provide power when the external power draw is above some threshold. So basically to extend my locally available maximum power. Right now it tries to keep external power draw to 0W. I'd be interested in tapping anything below 1kw from the grid but above that I would like the SI to kick in to help.
Unfortunately SMA documentation and support are extremely poor (or nonexistant really) -- they only talk to professional installers. There are a million configuration options with no documentation and I can't tell if any of them could help me to solve these problems.

Edit: apologies, it seems I've written into a wrong section. Perhaps the mods can move this post to its proper place.
 
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svetz

Works in theory! Practice? That's something else
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I'm surprised to hear that about their tech support, @Hedges might have some insight
 

Hedges

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I only have experience with SI-5048US/6048US, not the newer 8.0 and other such models.
Most of what I learned about it, I learned from reading the manual and other sources.

The 8.0 probably has different functions related to grid, especially time of use and export, but I'm not sure. So features of using battery when available and grid if needed I don't know about (except treat grid as generator based on SoC as you mention.) I would guess what you want is a reasonable management function for Home Manager, but I'm not familiar with it.

With mine, I can set a maximum current draw from the grid, e.g. 10A. If demand exceeds that, SI would produce the power inverting from battery.
Used with Sunny Boy, it charges batteries however it wants from PV (up to max battery current), charges from grid up to maximum charge from grid parameter, and lets surplus PV production backfeed the grid.

It should manage current through grid connection, except in the case of PV delivering too much. Mine only controls Sunny Boy output by frequency shift, which can only occur disconnected from grid. We are not supposed to exceed 6.7kW per SI. European 220V model would allow about twice that (but for your 10A, only 2200W). Yours probably uses Home Manager and data cable to command Sunny Boy.

I talk to support via email. Typically this has been something like a Sunny Boy that didn't seem to interact as expected (not varying its power output), and they requested serial numbers and upload of log files. That took commands writing to SD card in my case, yours is probably transferred over data cable.
 

Harakas

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Joined
Nov 24, 2021
Messages
2
Thanks for the reply. I understand that the SI-5048US still uses the old method of having the disconnect inside the sunny islands, so AC2 is connected to grid/generator and AC1 to the house, while the new "on-grid" installation documentation for 4.4/6.0/8.0 now mandates installing it like an inverter on a grid with an external contactor for disconnecting the house from the grid and you do not connect anything to AC1.

I guess that makes sense for beefier systems where you can size the contactor appropriately and there is only one way to do the installation simplifying (dumbing down) the available options as I guess most people would actually want to do it this way -- and SMA can get away with cheaper components inside the SI. Unfortunately it seems many features of the old system have disappeared or regressed with this method. That is quite unfortunate. I guess the main application for users is battery based energy saving instead of backup so it doesn't get that much love from the management.
 
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