question

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kevinc-63559 asked

Peak shaving sanity check

Looking to build a peak shaving system.

My local electric Coop here in NE Missouri has added a charge for "Peak Demand" based on the highest 15 minute demand during the billing month. I know it will take 1000+ years to pay for itself with just Multipluses and batteries, and therefore solar will be added later, but will not be present initially.

So, system will simply be: Grid connected panel -> dual Multipluses in split phase 240V mode with 48V battery bank -> load panel.

Having spent a bit of time reviewing the Peak Shaving threads here, some YouTube videos, and related information, I'm pretty sure all I'll need to do is set my AC input limit to the peak current I want to pay for. If I understand correctly, the Multipluses will supplement demand via the batteries when the peak current demand is exceeded, and recharge when peak current demand is lower than the setting. This is simple and perfect presuming it works that way.

I currently have a single Multiplus 12/3000/120-50 120V unit connected to 200amps of battery as a UPS system for my computer and related nearby equipment. Alas the current draw is well below the minimum of 9.7 amps, so can't really test this shy of hooking up something like a space heater. It would be nice, although trivial, to try and setup this system to do what I'm looking for above. I've played a little bit with Assistants, but if I'm understand them correctly, they can only provide an either/or solution: pull from AC In or pull from batteries. Can't use ESS because 1) I NEVER want to back feed into the grid and 2) I didn't spot a country code for the USA, so can't enable the ESS assistant.

Do I have the basic concepts down right?

Any suggestions for bypassing the 9.7 amp lower limit on my current system to shave a few hundred watts of my demand (and get some use from the pair of batteries beyond grid outage protection)?

Thanks in advance.

Multiplus-II
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1 Answer
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nickdb answered ·

You can load an "other" grid code which will allow ESS to work. It does not backfeed by default, but even without solar you do get the benefit of some of its features like scheduled charging etc. What the legalities are in your region, that you will need to check.

Without ESS you would be using power assist to supply above grid input limits.

You can also use AC ignore to automaticaly disconnect/reconnect the grid under specific conditions.

There is a lot of control, and you will need to do a fair amount of research.

Everything you are looking for has been done already and there will be multiple topics on the community that will help you.

Get a head start and do the free online training, it really is worth it.

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