Hybrid Inverter and Grid Tied Solar questions

[1201]

You don't have to give up the existing inverter and selling back some solar. I've still got my grid-tied inverter, but I maximize the solar value by utilizing the off-grid inverter and batteries until batteries are at 100% and then utilize the grid-tied inverter if I have excess solar.

That seems like the complex way to do it

 

[1201]

The nominal battery pack voltage in my system, which is 128S 3.4V LFP cells or (8) 51.2V batteries is series is 409.6V nominal in 3 strings, each string as its own circuit breaker and a combined voltage / current meter so I can watch current sharing for charging ( its so far dam near perfect ) likely due to the low current involved, so the voltage drop is not an issue that 49V systems has. I charge at 10 amps ( 4kW ) which is only 20% of the inverter rating, system is whole home backup only and I'm grid tie with 15kW solar.

2 of the 3 stings are 50Ah each ( 100Ah total ) and after the circuit breaker(s) is parallel with the BYD batterybox HV ( 10 kWh ) which has canbus closed loop with the slave S6.

The 3rd is 30Ah parallel after the circuit breaker with the Seplos Hitens ( which are parallel each 20kWh) and is closed loop with the master S6, technically 55Ah total

Solis S6 Hybrid 11.4kW * 2	Closed Loop Battery	Open Loop Battery
Master	Seplos Hiten 20kWh * 2	Generic 12kWh
Slave	BYD 10kWh	Generic 20kWh * 2

The primary concern / issue with series battery's is when one battery in the string discharge mosfets in a generic BMS goes offline you can have very large voltage across the offline battery as the positive of the total string will go to ground from the inverter battery positive, could be up to negative 3XX volts which would have the BMS FETS blow up. ( single series string )

So when a "dumb" string is paralleled with a string with communications, it is protected as the two possible cases are:

• Communicating battery goes offline, inverter shuts down the battery port, naked battery safe
• No communications battery goes offline, communicating battery maintains the string pack voltage so no large voltage differentials on an individual battery.

Wire size:

Since this is HV, the S6 has a maximum continuous rated battery current of 50 amps and the pack voltage is ~409V is well above the inverter rating of 11,400 watts. And at 11.4kw that's only a draw of ~28 amps , so 10 awg is fine for the battery and that is actually less as that is split between 3 battery's, less than 10 amps each at full rated load.

One can use lower pack voltages, but you need ~230 as a minimum @ 50A for the 11.4kW rating and just keep in each battery cell count an even divisor of the total pack voltage of the battery with closed communications to the inverter of the parallel pack voltages are the same.

As for concerns about current sharing the parallel packs, uneven discharge will rotate from pack to pack as the charge or discharge ( ohms law ), but be close enough for bottom and top SOC anything in-between is unknown and doesn't have any functional value as one has no control even if all batteries were perfect in reporting SOC.

The down side of this is this system isn't UL9540 ( BYD and S6's are is but nothing else )

Works great, fun project to build and keep me busy, your mileage will vary if you should choose this path.


View attachment 283314View attachment 283315View attachment 283316

Thanks for the info!

So the hiten is 5 boxes

I'm guessing 4x 5kwh boxes and what is box number 5?

Does each hiten module have a built in BMS? Or how does the hiten system work

 

[Solar Guppy]

Do you have separate breakers on the AC grid side for each S6? If so, what size breaker are you using? On the AC backup side, do you have separate breakers on each S6? If so, what size breaker are you using? I have not yet commissioned mine yet, but are you able to set current limits on both Grid and Backups so as not to over current the busbar if you don't have a 200 amp panel?

Lets start with from a code prospective, breakers are only for the wiring or busbars in the panel(s), nothing else.

I have breakers for both grid and backup for each inverter 60 amps, so four total It is not a code requirement, this was for convivence.

Yes you can program maximum power to the grid ( grid-tie sell energy ).

Typically you would have a critical loads panel and if your concerned about an overload condition, the breaker that feed the S6 would be sized for your sell energy / bus-bar limits ( or 120% rule ) and the critical loads panel feed is sized for what the inverter is rated for which should be less than the bus-bars in the critical loads panel. Then you have individual breakers in the critical loads panel.

Now this is what I did, as I have what is called a split-bus main panel aka generator panel which as the interlock factory installed and the upper rwo thirds of breaker slots is powered from the the grid OR from the generator input. So no need for a second panel.

 

[Solar Guppy]

Thanks for the info!

So the hiten is 5 boxes

I'm guessing 4x 5kwh boxes and what is box number 5?

Does each hiten module have a built in BMS? Or how does the hiten system work

Top "box" is the master BMS ( it uses contactors ), breaker, display and communication ports, there are slave bms in the other boxes. If you look up an orion bms which DYI users can build there own HV batteries, it functionally the same thing

 

[woe]

Correct, that is true of pretty much all ac coupling systems. Look up the Victron factor 1 rule for explanation.

The RUiXU RX-12k and the EG4 connect the ACPV to the Generator port of the inverter. I guess this means that the inverter can have some intelligence on how it uses it.

When I read reading about the Deye it seemed to be about to control the ACPV pretty much the same was it can control the DC Solar, which doesn't seem to be the case of it's connected to one of the load centers.

Does your 14.8kw system ever produced more than 11.4kw at any point in time?

The maximum it's actually produces at one time is probably close to 10kw as I have them on the SE and SW faces of my roof at it doesn't max out so any point during the day.

Are you and to supply the system up into two different outputs? Some going to backup sides and some going to grid side?

The PVs micro inverters all terminate in the Enphase combiner so I'm not sure if I can separate them but I also don't think I'd want to play around with it either.

Yes if is connected to the grid side you will not have solar when the grid is down but your inverter will still operate off battery . Do you have a lot of grid down time?

This is a good question. I read that too and was confused

Yeah this is so weird. I'm in the Houston area so it's and no. In the last 7 years. 2017 Hurricane Harvey (up to 1 week), 2021 freeze (4 days on and off), last year (4 days on and off) was up to 2 weeks for some people. Plus the standard 20 mins - 1 hour here and there occasionally.

Being able to change the battery of solar off grid is probably a requirement for me.

 

[woe]

I've posted before about this previously, here is one example

Also off the shelf, plug and play Seplos Hitens for 2440 per 20kWh, linked in another post

Can you post a link to the actual battery you bought?

That's not the big benefit. Still, 3 cents can be better than zero cents. With off grid, when the battery is full you just lose all the potential power. Why not get the 0.03 per kWh for it?

Since the op is already connected he can support ALL loads via solar and battery. With an off grid inverter he can only support BACKUP loads and never home loads. So with interconnection he can get by with a smaller inverter and less battery and still save the same or more

I agree, I've basically come to the conclusion buy back has almost no real world value now. In my lowest use month it was $22 at 3c/kWh.

I'm better off putting as much as I can into batteries and using it.

 

[1201]

The RUiXU RX-12k and the EG4 connect the ACPV to the Generator port of the inverter. I guess this means that the inverter can have some intelligence on how it uses it.

When I read reading about the Deye it seemed to be about to control the ACPV pretty much the same was it can control the DC Solar, which doesn't seem to be the case of it's connected to one of the load centers.

Ac coupling is traditionally done in the load port. The hybrid sends a signal to the grid tie to modulate output.

It does this by raising frequency.

The new hybrids usually have the grid always connected. An inverter cannot modulate the frequency of the grid so they ac couple to the Gen port that way they simply disconnect the Gen port when the battery is full

The maximum it's actually produces at one time is probably close to 2 as I have them on the SE and SW faces of my roof at it doesn't max out so any point during the day.

I think you should be fine, especially since you are exporting he'll to grid as soon as the battery is till

The PVs micro inverters all terminate in the Enphase combiner so I'm not sure if I can separate them but I also don't think I'd want to play around with it either.


Yeah this is so weird. I'm in the Houston area so it's and no. In the last 7 years. 2017 Hurricane Harvey (up to 1 week), 2021 freeze (4 days on and off), last year (4 days on and off) was up to 2 weeks for some people. Plus the standard 20 mins - 1 hour here and there occasionally.

Being able to change the battery of solar off grid is probably a requirement for me.

 

[woe]

The nominal battery pack voltage in my system, which is 128S 3.4V LFP cells or (8) 51.2V batteries is series is 409.6V nominal in 3 strings, each string as its own circuit breaker and a combined voltage / current meter so I can watch current sharing for charging ( its so far dam near perfect ) likely due to the low current involved, so the voltage drop is not an issue that 49V systems has. I charge at 10 amps ( 4kW ) which is only 20% of the inverter rating, system is whole home backup only and I'm grid tie with 15kW solar.

2 of the 3 stings are 50Ah each ( 100Ah total ) and after the circuit breaker(s) is parallel with the BYD batterybox HV ( 10 kWh ) which has canbus closed loop with the slave S6.

The 3rd is 30Ah parallel after the circuit breaker with the Seplos Hitens ( which are parallel each 20kWh) and is closed loop with the master S6, technically 55Ah total

Solis S6 Hybrid 11.4kW * 2	Closed Loop Battery	Open Loop Battery
Master	Seplos Hiten 20kWh * 2	Generic 12kWh
Slave	BYD 10kWh	Generic 20kWh * 2

The primary concern / issue with series battery's is when one battery in the string discharge mosfets in a generic BMS goes offline you can have very large voltage across the offline battery as the positive of the total string will go to ground from the inverter battery positive, could be up to negative 3XX volts which would have the BMS FETS blow up. ( single series string )

So when a "dumb" string is paralleled with a string with communications, it is protected as the two possible cases are:

• Communicating battery goes offline, inverter shuts down the battery port, naked battery safe
• No communications battery goes offline, communicating battery maintains the string pack voltage so no large voltage differentials on an individual battery.

Wire size:

Since this is HV, the S6 has a maximum continuous rated battery current of 50 amps and the pack voltage is ~409V is well above the inverter rating of 11,400 watts. And at 11.4kw that's only a draw of ~28 amps , so 10 awg is fine for the battery and that is actually less as that is split between 3 battery's, less than 10 amps each at full rated load.

One can use lower pack voltages, but you need ~230 as a minimum @ 50A for the 11.4kW rating and just keep in each battery cell count an even divisor of the total pack voltage of the battery with closed communications to the inverter of the parallel pack voltages are the same.

As for concerns about current sharing the parallel packs, uneven discharge will rotate from pack to pack as the charge or discharge ( ohms law ), but be close enough for bottom and top SOC anything in-between is unknown and doesn't have any functional value as one has no control even if all batteries were perfect in reporting SOC.

The down side of this is this system isn't UL9540 ( BYD and S6's are is but nothing else )

Works great, fun project to build and keep me busy, your mileage will vary if you should choose this path.


View attachment 283314View attachment 283315View attachment 283316

This all looks pretty amazing. But that's looks like more space that I have, and a lot more equipment than I want to install. I'm really hoping for 1 inverter and a couple 48v 300Ah Batteries.

I'm more than a little jealous but I'll looking for a cost effective simple solution that will fulfill my requirements that I can hopefully install in a few hours 1 afternoon.

But seriously, thanks for sharing.

 

[woe]

Ac coupling is traditionally done in the load port. The hybrid sends a signal to the grid tie to modulate output.

It does this by raising frequency.

The new hybrids usually have the grid always connected. An inverter cannot modulate the frequency of the grid so they ac couple to the Gen port that way they simply disconnect the Gen port when the battery is full

Is there any negatives to having the ACPV connected to the gen port of the me inverters?

I think you should be fine, especially since you are exporting he'll to grid as soon as the battery is till

 

[1201]

Is there any negatives to having the ACPV connected to the gen port of the me inverters?

Nope

 

[Offthewall]

No need for a hybrid but for the cost the Schneider XW Pro is hard to beat. $2650 for 2 shipped gets you 13.6kw continuous 16kw for 30min, and 27.2kw surge output.

As for batteries, DIY is your cheapest option. 18650batterystore has 280ah eve cells for $72 each if you buy 32. $2304 shipped for 28.7kwh of battery. Add another $200 or so for BMS and breakers. Or if you want to be fancy $1,000 or so for 2 DIY Battery boxes.

 

[1201]

No need for a hybrid but for the cost the Schneider XW Pro is hard to beat. $2650 for 2 shipped gets you 13.6kw continuous 16kw for 30min, and 27.2kw surge output.

As for batteries, DIY is your cheapest option. 18650batterystore has 280ah eve cells for $72 each if you buy 32. $2304 shipped for 28.7kwh of battery. Add another $200 or so for BMS and breakers. Or if you want to be fancy $1,000 or so for 2 DIY Battery boxes.

Yes you cannot beat a diy battery.

I'm not do sure about the xw pro though. The grid interactive features are not great. But it's a great low frequency inverter

 

[woe]

No need for a hybrid but for the cost the Schneider XW Pro is hard to beat. $2650 for 2 shipped gets you 13.6kw continuous 16kw for 30min, and 27.2kw surge output.

As for batteries, DIY is your cheapest option. 18650batterystore has 280ah eve cells for $72 each if you buy 32. $2304 shipped for 28.7kwh of battery. Add another $200 or so for BMS and breakers. Or if you want to be fancy $1,000 or so for 2 DIY Battery boxes.

I'm most likely going to go DIY. For the fun of building, knowing how they work and repairability.

But I found these on AliExpress.
16kWh for $1712. Or $107/kWh. Free but Long 70 days delivery.

https://a.aliexpress.com/_mMsi8eT

Would come to $3450 for 32kWh. Seemed pretty dang good..

 

[woe]

No need for a hybrid but for the cost the Schneider XW Pro is hard to beat. $2650 for 2 shipped gets you 13.6kw continuous 16kw for 30min, and 27.2kw surge output.

As for batteries, DIY is your cheapest option. 18650batterystore has 280ah eve cells for $72 each if you buy 32. $2304 shipped for 28.7kwh of battery. Add another $200 or so for BMS and breakers. Or if you want to be fancy $1,000 or so for 2 DIY Battery boxes.

Please forgive my ignorance but why don't I need hybrid? I assumed since I'm on grid 99.9% of the time I'd need Hybrid as opposed to an off grid inverter.

 

[woe]

Ac coupling is traditionally done in the load port. The hybrid sends a signal to the grid tie to modulate output.

It does this by raising frequency.

The new hybrids usually have the grid always connected. An inverter cannot modulate the frequency of the grid so they ac couple to the Gen port that way they simply disconnect the Gen port when the battery is full

I think you should be fine, especially since you are exporting he'll to grid as soon as the battery is till

Yeah I just read more explaining how load tying the ACPV works and since I don't produce more than 10Kw at any one time the Solis S6 could work well for me and save me an extra $800. I assume I could also wire a generator into the panel (or a manual transfer switch with the ACPV) to switch to generator when there is not enough solar. My generator is only 9kw so no over power issues there either.

 

[1201]

Yeah I just read more explaining how load tying the ACPV works and since I don't produce more than 10Kw at any one time the Solis S6 could work well for me and save me an extra $800. I assume I could also wire a generator into the panel (or a manual transfer switch with the ACPV) to switch to generator when there is not enough solar. My generator is only 9kw so no over power issues there either.

It would have $800 but the battery would be more expensive but wire would be less expensive. I think the cost would be a wash.

Per the manual yeah you could do a generator into the grid side with a transfer switch or Gen lockout.

 

[woe]

It would have $800 but the battery would be more expensive but wire would be less expensive. I think the cost would be a wash.

Per the manual yeah you could do a generator into the grid side with a transfer switch or Gen lockout.

Oh yeah I forgot this was HV..... Dang. I guess I'm back to the RUiXU or EG4.

My cable runs are going to be pretty short.

According to the attached, For 200A batteries (no matter the V) I'm reading i need 2/0 copper. Does that sound about right?

 

[1201]

Oh yeah I forgot this was HV..... Dang. I guess I'm back to the RUiXU or EG4.

My cable runs are going to be pretty short.

According to the attached, For 200A batteries (no matter the V) I'm reading i need 2/0 copper. Does that sound about right?

That's very voltage dependent.

 

[woe]

That's very voltage dependent.

I'm such a n00b. I'm sorry. None of the charts I read referenced volts.

48V less than 6ft run 200A BMS battery. 2/0 should be right?

 

[1201]

I'm such a n00b. I'm sorry. None of the charts I read referenced volts.

48V less than 6ft run 200A BMS battery. 2/0 should be right?

Lol we're all noobs.

Yes 2/0 should be good for such a short run

 

[bhbaker220]

That seems like the complex way to do it

If incremental money spent is no objective, then of course spend freely. I had read into the OP that cost was a big factor in justifying the cost savings. Most of Texas has some of the lowest grid prices in the U.S. so the benefits of solar are not as significant as some other areas which makes payouts longer and ROI lower. The only things the users have control over is their usage and how much they pay for solar costs.

 

[Offthewall]

Please forgive my ignorance but why don't I need hybrid? I assumed since I'm on grid 99.9% of the time I'd need Hybrid as opposed to an off grid inverter.

You are not planning on this inverter selling back to the grid so no need for a hybrid inverter. An off grid inverter will do what you are wanting. That said, you may want one that will do ac coupling in a grid down situation so your grid tied solar array will produce power for you to use.

I mentioned the XW because it does AC coupling. It is a hybrid inverter but you can configure it to not sell to the grid.

Another option would be EG4 12000xp. The manual mentions AC coupling via the smart load breaker….

 

[woe]

You are not planning on this inverter selling back to the grid so no need for a hybrid inverter. An off grid inverter will do what you are wanting. That said, you may want one that will do ac coupling in a grid down situation so your grid tied solar array will produce power for you to use.

I mentioned the XW because it does AC coupling. It is a hybrid inverter but you can configure it to not sell to the grid.

Another option would be EG4 12000xp. The manual mentions AC coupling via the smart load breaker….

Yes I certainly am looking for AC Coupling.

I need 12kw output so was looking at the EG4 18kpv. But wanted to spend a little less if possible. I need to look more into the Schneider but I was under the impression they were more expensive.

Cam

 

[1201]

If incremental money spent is no objective, then of course spend freely. I had read into the OP that cost was a big factor in justifying the cost savings. Most of Texas has some of the lowest grid prices in the U.S. so the benefits of solar are not as significant as some other areas which makes payouts longer and ROI lower. The only things the users have control over is their usage and how much they pay for solar costs.

Yeah I disagree strongly with you on this one.

If op goes with an off-grid inverter, to save money they MUST install a backup panel. The backup panel will only contain a few circuits meaning they will still have loads on the main panel that cannot be supported by battery.

It will be questionable if they can support their largest loads. Op is in Houston- would an off grid inverter reliably start their 5 ton ac?


With a hybrid inverter, op does not even need to install a backup panel. They can support the main panel from battery. Which also means it can support ALL loads via battery, and op does not have to worry about surges since the grid handles that.

 

[bhbaker220]

Yeah I disagree strongly with you on this one.

If op goes with an off-grid inverter, to save money they MUST install a backup panel. The backup panel will only contain a few circuits meaning they will still have loads on the main panel that cannot be supported by battery.

It will be questionable if they can support their largest loads. Op is in Houston- would an off grid inverter reliably start their 5 ton ac?


With a hybrid inverter, op does not even need to install a backup panel. They can support the main panel from battery. Which also means it can support ALL loads via battery, and op does not have to worry about surges since the grid handles that.

You can easily put a Micro Air soft start on the AC. I’m running my 4 ton with a 6000XP which saves a ton over a hybrid. Also, you don’t have to power the whole house and charge an EV on the off grid inverter. He has a subpanel already that he can tie into. I’m running a subpanel, pool pump, AC, blower fan, and have the microwave and dishwasher tied in for when the grid goes down. Of course every one’s usage is different but if measure it with a clamp meter or Emporia Vue, you can make a wise selection on critical loads and where the big savings are on one’s utility bill. Our power went out on the 4th for four hours. Most of the homes around us have whole home generators they did not miss a beat. We did not either and far a fraction of the up front cost and expenses. In the greater Houston area, you just need AC in the summer and be able to keep the fridge(s) and freezer(s) going and a few lights in case of an extended power outage.

Hybrids are nice. If someone gave me one, I’d install it but I would not pay the premium for it. But that’s just me. Your situation could be different.

It looks like “Offthewall” has a similar perspective to me on post #47. You might want to disagree strongly with him