Anker Solix, Zendure, Ecoflow, Storcube style hubs for DIY system

Right now there's quite a few systems around that basically have a hub that connects to a proprietary battery and then connects to any standard micro grid tie inverter. This allows you to easily add battery storage to an existing system that uses micro inverters, but I can't see them ever paying for themselves because the batteries are too expensive. Does anyone know of a way of achieving the same system (please don't say hybrid inverter) if you already have a solar system which uses micro inverters and a DIY battery bank.

All of the plug and play systems that I mentioned in the title essentially work out at about €1000/kWh of storage, which you'd never make back in savings, so I'd like to find a DIY solar hub that can work with my existing 5kWh battery and Hoymiles inverter. Essentially all these systems are is a solar charger with a bypass feature that can direct power to the battery or the inverter and then eventually from the battery to the inverter when there's no sun.

I know that a hybrid inverter does pretty much the same thing but also includes an inverter, but for various reasons I'd prefer not to add a new inverter to my system and just add a hub to manage my battery.

Unless I'm missing something, those products you mention have an inverter anyway. If you are using micro-inverters, you would, presumably, need some form of AC-coupled storage system .

Can you explain how your "existing 5kWh battery and Hoymiles inverter" are connected already? And what you mean by "hub" compared to "inverter"?

P.S. I'm thinking all you need is something like the Solis RAI AC coupled Energy Storage inverter - but you say you don't want another inverter!

SeaGal said:

P.S. I'm thinking all you need is something like the Solis RAI AC coupled Energy Storage inverter - but you say you don't want another inverter!

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Look at the photo of how the zendure system works. The PV comes into the hub and then the hub either acts as an MPPT charger and directs the power to the battery or bypasses the PV to the Hoymiles inverter. Then it can also act as a load controller taking energy from the battery at night and sending it to the ineverter.

Right now I don't have an easy way of adding my battery to my solar system. I have solar panls connected to a hoymiles inverter and then I just have a battery sat doing nothing. If I could find a DIY version of the Zendure hub then I could use it with my DIY battery which is made up of 4x 12v 100Ah lifepo4 batteries.

What about hopping on AliExpress and finding someone to send you the appropriate AC grid forming / storage inverter from LuxPower? They can probably send you one with the right capability for $1500. There’s at least two in their international catalog that can do what I think you want.

Oops you said “no hybrid inverter”. Can you explain how you think that is possible when you have to use an AC microinverter string as an input. Or does Hoymiles do more string inverter than microinverter business in your country

Hmm your original writeup is kind of contradictory. You mentioned microinverters but then alluded to string switching. That seems super hard with microinverters unless you have them mounted accessibly. You would need A LOT of switches. On the plus side they only need to be 60VDC rated

How many panels do you have? Are your panels on the roof? That is a lot of extra wires.

Each Solarflow HUB 2000 has 2 mppt, each able to handle 900 watts.

Allows 900 watt strings into a smaller micro inverter. It seems like the power is scheduled, rather than on demand (no CT's).

Instead of doubling up on inverter, you are doubling up on MPPT.

I would rather double up on inverters (hybrid inverter) than MPPT (not using the MPPT built into the micro inverter). With the hybrid, you get more peak power (micros + hybrid), ability to zero export with CT's, and no additional wires from the roof.

Seems like the Hub 2000 is designed for an apartment, and/or way to stay under the 3kW limit before you need a permit to connect.

zanydroid said:

Hmm your original writeup is kind of contradictory. You mentioned microinverters but then alluded to string switching. That seems super hard with microinverters unless you have them mounted accessibly. You would need A LOT of switches. On the plus side they only need to be 60VDC rated

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I think I actually found something that does what I'm looking for, but my German isn't that great so I'm a bit scared to order.

DIYrich said:

SolarFlow Hub 2000

Use Zendure SolarFlow storage for balcony power plant to maximize the use of electricity generated by the balcony power plant, to increase self-consumption in the field of energy consumption and to save on your electricity bills.

eu.zendure.com

Each Solarflow HUB 2000 has 2 mppt, each able to handle 900 watts.

Allows 900 watt strings into a smaller micro inverter. It seems like the power is scheduled, rather than on demand (no CT's).

Instead of doubling up on inverter, you are doubling up on MPPT.

I would rather double up on inverters (hybrid inverter) than MPPT (not using the MPPT built into the micro inverter). With the hybrid, you get more peak power (micros + hybrid), ability to zero export with CT's, and no additional wires from the roof.

Seems like the Hub 2000 is designed for an apartment, and/or way to stay under the 3kW limit before you need a permit to connect.

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I only have a small system, currently 4 panels (soon expanding to 6) which are on a roof that is easily accesible and access directly below to install the batteries. Staying under the 3kW is exactly what I want to do.

That is a creative solution, I guess. It's not that complicated of a power architecture.

That is a two port HM800.

It uses a buck MPPT to adapt down the string to within the voltage range of a microinverter and hook up a SCC. And then it has some modest on-off power switcher+PLC in that Akku thing.

I'm not sure why this is good -- it probably has to do with staying within the power limits of porch size grid tie installs.

(wrote this before seeing your updates) I take it you have a porch install and not a substantially large install (that's a key detail). I have 45 panels on HM microinverters and we don't have porch sized installs here in the US.

I'd pick AC coupling and paying more for the privilege, over a spaghetti of wires on the DC side.

FWIW there are threads here feeding microinverters from batteries. Sort of like different take on a GTIL.

zanydroid said:

That is a creative solution, I guess. It's not that complicated of a power architecture.

That is a two port HM800.

It uses a buck MPPT to adapt down the string to within the voltage range of a microinverter and hook up a SCC. And then it has some modest on-off power switcher+PLC in that Akku thing.

I'm not sure why this is good -- it probably has to do with staying within the power limits of porch size grid tie installs.

(wrote this before seeing your updates) I take it you have a porch install and not a substantially large install (that's a key detail). I have 45 panels on HM microinverters and we don't have porch sized installs here in the US.

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Exactly that, Europe has some funny rules for small DIY systems which limit the amount of red tape if you stay below a certain size. These type of systems usually weren't adapted to working with any sort of battery until recently, hence the sudden flooding of the market with the systems I mention in the thread title.

Going the route I want means that the end device that plugs into the house remains homologated and I don't have to pass any electrical inspection. If I wanted to add a hybrid inverter then I'd have to add a DC breaker box, an AC breaker box, put labels all over my electrical system to conform with standards and then get someone to come and inspect it.

Nobody has made a 3kW hybrid yet that sits between the old plug-in microinverters and the wall, that cannot be adapted to 48V batteries with some surgery?

Can you use certified power control system setting to limit to 3kW and bypass inspection? Many hybrids that target the US have that because 10kW-AC is a common limit below which things are easier. The power limiter is tested by an NRTL to a UL standard. Once the distributor locks it to the necessary power level, you send some attestation / certification that the locking was done.

How much work are the permits and inspection really? A lot of people in the US fear it more than necessary. My electrical inspection was 30 min, I was allowed to do all wiring myself. Drafting of permits can be outsourced for $400 in the US, with the remaining work on my part filing forms with the city and power company.

(Anyway there are designs on this forum for switching the DC input of a bunch of microinverters if you want to do that, note that microinverters will draw full power from the batteries and there are multiple circuits and schools of thought on how the current limiting should be done. And it depends on what kind of output power level control you want to or need to have. Are you certain your power company will allow 3kW to be blasted onto the grid continuously when on battery power?)

zanydroid said:

Nobody has made a 3kW hybrid yet that sits between the old plug-in microinverters and the wall, that cannot be adapted to 48V batteries with some surgery?

Can you use certified power control system setting to limit to 3kW and bypass inspection? Many hybrids that target the US have that because 10kW-AC is a common limit below which things are easier. The power limiter is tested by an NRTL to a UL standard. Once the distributor locks it to the necessary power level, you send some attestation / certification that the locking was done.

How much work are the permits and inspection really? A lot of people in the US fear it more than necessary. My electrical inspection was 30 min, I was allowed to do all wiring myself. Drafting of permits can be outsourced for $400 in the US, with the remaining work on my part filing forms with the city and power company.

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To be honest I don't think the inspection (consuel in French) is that difficult to pass and it's only about €100. I don't have the space for a larger system though, so it's worth it to me to remain in the lower limits and stay clear of any inspection requirements.

OK.

IMO Solix, EcoFlow, etc are optimized for a certain kind of user that wants everything self-contained and easy looking. Sometimes compact wrt the minimum size system. There is a premium for this, and the systems don't necessarily stay compact compared to other systems when they scale up.

I'd probably prefer to deal with AliExpress sellers than learn German so I can research that artisanal looking hack. The problem is that as a AC side system you will need to confirm it has the necessary grid certifications. This may well be the reason that there are only expensive boxes for this right now.

For the DC thing

Oh yeah, you might need the battery protect because there could be funky voltage coming back on the HM. I believe they use isolated topology so they are mains isolated. But on some HM models with internal input paralleling voltage on one port can go to the other port. HM-1000,1200,1500 have that.

That problem goes away if you have everything powered through that Akku thing, vs that half & half design they have.