Battery backup solution?

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Battery backup solution?

Post by electric_monk » Mon Aug 17, 2020 6:07 pm

Hi all,

Last year I had solar installed on my SF Bay Area home. I'd considered DIY install, but was a little worried about heights (parts of the house are two storey) and I'd lived in the house less than a year anyway - local city code says you can only pull permits for DIY work if you've lived in the home longer than that.

Either way, I ended up with a 7.6kW system based on Panasonic panels and a SolarEdge HD Wave inverter (the 7600 model). The inverter is just the plain model so it has no provisions for battery backup (not even a 'single outlet' mode like some vendors offer), and I can't actually see individual panel stats on the monitoring login so I'm a little annoyed at the installers for keeping secrets from me anyway. I do also find it mildly sinister that I repeatedly told them "as large a system as you can fit" and the output of the panels exactly matched the size of the inverter they picked.

Is there an easy solution using OutBack stuff to add battery backup? I specifically don't want to do Tesla Powerwalls as the full installed price exceeds what I paid for the solar system, and I don't feel the need for lithium ion/etc. batteries in a non-mobile situation (e.g., weight or overall energy density doesn't matter for a house as much as it does a car).

I did have a look at some of the products, and there was some suggestion that there's OutBack hardware that will work with an existing inverter, but I wasn't clear whether it'd work in all configurations (e.g. charging + powering while grid is offline but sun is up). There's also the SkyBox, which looks like a really lovely bit of hardware, but would require replacing the current inverter (and possibly I'd need two of them, due to the size of my system? I have read some hints that the SolarEdge panel optimisers will work fine with the OutBack units, at least)


Mike Curran
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Re: Battery backup solution?

Post by Mike Curran » Tue Aug 18, 2020 9:59 am

If I were you I would contact Solaredge directly to see what my options are for adding battery storage. This document ... ngle-phase#/ says two things about their inverters that seem in conflict with what you're saying:

1. "In addition to its functionality as a DC-optimized PV inverter, the single phase inverter also manages battery and system energy as part of SolarEdge’s StorEdge solution." So it sounds like your inverter could incorporate battery storage, but when I looked into the Storedge solution it sounded like you would need to replace your existing inverter - that's confusing at least, and misleading at worst;

2. "Key Benefits: Built-in module-level monitoring" - not what you're saying.

Again, advise you contact Solaredge Tech Support.

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Re: Battery backup solution?

Post by electric_monk » Tue Aug 18, 2020 1:21 pm

Thanks for your reply. I'll give contacting SolarEdge a shot but I already did a lot of research into their offerings, so I'm pretty sure I know what they'll say.

Regarding 1) they make a bunch of variations on the same 'base model'. The base model is the one I have (confirmed as during installation, I ran hardwared ethernet to avoid having to pay for the cellular modem add-on) and it contains nowhere battery functionality could be attached. They have a couple of variants from the base model I have, one has built in EV charging (it just has a standard car charging cable hanging off of it) and one is the StorEdge version (which has a bunch of extra plastic in the same places as the EV version, but I assume that contains the battery electronics. Obviously haven't looked inside of one as I don't have one, though! It does make me wonder if the guts of my base model can do it and it just needs that extra circuitry, but they don't sell it as an add-on, they're all sold as complete single units from the factory). Last year they only supported LG Chem, but it looks like this year's new model they've added support for more battery vendors.

More interestingly, SolarEdge brought out a thing called the SolarEdge Interface, which adds battery storage to existing systems (currently only LG Chem) and also requires another StorEdge inverter for the battery side, but they specifically don't sell it in North America. They've been promising they will for over a year, though. If this were already out it'd be the obvious choice, assuming I could hunt down those LG Chem batteries (though as I specified, I don't particularly want high end batteries, I'd prefer heavier/cheaper options. I believe the LG Chem cells required are the same sort that go into things like the Chevy Bolt).

As such they'll probably recommend buying the new version of their inverter with the built in StorEdge functionality, and LG Chem batteries, and tossing the existing inverter (which to me means I should shop around for inverters anyway).

Regarding number 2, I apologise for that rant in my original post muddying the waters. That was entirely directed at the installers, who have specifically disabled access to the module-specific data on my SolarEdge login. The units all definitely have module data as I was careful to study all the system design and module installation instructions before the installers actually installed the system.

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