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8x HESP 12kW Advice

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user2562

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Looking for sanity check on my plan to use 8 x HESP 12kW for grid tie setup with full offgrid capability. Thanks in advance for any advice

Somewhat rural Texas property with a lot of ACs, pumps, etc. Need to be able to bypass inverter setup and run house panels directly from grid if inverters are not working (divorce is costly).

Diagram included. It's pretty simplified but hopefully explains what I'm thinking.

I have 320/400 single phase service. Meter has 2 sets of lugs. Each is connected to two 200A panels. I want to continue to make 200A available to each set of panels when grid is available, and ideally also make 200A available when grid is down to avoid tripping from high inrush devices.

Proposed Setup
  • 8 x 12kW hybrid grid tie inverters; 1-4 connected in parallel, 5-8 in parallel
    • Eyeing the HESP48120U200-H right now given price (~$1900 per unit)
  • Inverters will be export limited to prevent >320A back to grid
  • PV: initially will use already installed 65kW in 16 strings
  • Batteries: 15x 280Ah 48v batteries connected to all inverters via busbar.
  • House panels will continue to be connected to grid via main breaker that is normally switched off. Inverters will backfeed into house panels. Lockout to prevent main breakers and inverter breakers from being on concurrently
More on PV
  • 15 strings of 9x Canadian Solar BiHiKu bifacial 450W CS3W-450MB-AG
  • 1 string 10x Talesun 400W (Black) 108 Half Cell Bifacial
  • Future: Up to 16 additional strings Jinko 54HL4R-B (type N) 440W, up to 12 panels long each
    • Initial plan will be to use the 16x existing strings across all 8 inverters (leaving them quite underpaneled). I ordered a large # of Jinko 54HL4R-B (type N) 440W panels to potentially add an extra 16 strings. They should arrive in next couple weeks but will take a lot of time to get to installing
  • 500ft from inverters to panel, so keeping string voltage high is helpful
main.drawio (2).png
 
so thinking about the house panels system : after the lugs but before the 200a load centers , youll have a tap box with polaris taps to feed grid to inverters,

and after the tap box youll have a transfer switch to select either inverters or grid to feed the 2 house panels?
 
1201 said:
so thinking about the house panels system : after the lugs but before the 200a load centers , youll have a tap box with polaris taps to feed grid to inverters,

and after the tap box youll have a transfer switch to select either inverters or grid to feed the 2 house panels?
Click to expand...
as currently envisioned, no transfer switch. Each house panel connected to meter via main breaker. Also connected to inverters via 70A breakers. Lockout to prevent both from being on.

After the lugs but before the 200A house panels: polaris tap that connects fused lockable disconnect (going to inverters) + house panels + meter; this is located in an exterior wire trough

Another approach could be to use manual transfer switches (and combine load side of inverters into another load center first). I was thinking that might be more costly and require more wall space (two transfer switches and two more 200A load centers).
 
user2562 said:
as currently envisioned, no transfer switch. Each house panel connected to meter via main breaker. Also connected to inverters via 70A breakers. Lockout to prevent both from being on.
Click to expand...

What kind of lockout do you have in mind?
 
Do you have any current load monitoring to know what your max sustained load is?
You may be able to get by just fine with less .... I'm not advising against 8, it just seems like a whole boatload of power.
I can't offer much advice on the grid tie side of things but I will suggest building your own buss bar with some long flat stock from Zoro or the like. It will make wiring way easier... I used one of those you linked for a 3S build, it was much easier with the longer bars I got from Zoro. Short pack + wires to a Class T fuse to a + Bus near by and all the BMS connecting to the - buss on the other side.

I'm looking forward to updates on how this goes. 215KWh pack! Wow I hope to get there someday.
 
42OhmsPA said:
Do you have any current load monitoring to know what your max sustained load is?
You may be able to get by just fine with less .... I'm not advising against 8, it just seems like a whole boatload of power.
I can't offer much advice on the grid tie side of things but I will suggest building your own buss bar with some long flat stock from Zoro or the like. It will make wiring way easier... I used one of those you linked for a 3S build, it was much easier with the longer bars I got from Zoro. Short pack + wires to a Class T fuse to a + Bus near by and all the BMS connecting to the - buss on the other side.

I'm looking forward to updates on how this goes. 215KWh pack! Wow I hope to get there someday.
Click to expand...
Unfortunately I do not have good load monitoring. I agree, this is probably excessive, but required to get 200A passthrough using the HESP. I don't want the high inrush stuff to trip.

If I did Growatt SPH10k I would probably do 6x for 60,000 250A since each unit has grid passthrough of 63A, allowing 3x to get ~190A passthrough. I can deal with maybe tripping when a pump turns on when grid down.
 
user2562 said:
Unfortunately I do not have good load monitoring. I agree, this is probably excessive, but required to get 200A passthrough using the HESP. I don't want the high inrush stuff to trip.

If I did Growatt SPH10k I would probably do 6x for 60,000 250A since each unit has grid passthrough of 63A, allowing 3x to get ~190A passthrough. I can deal with maybe tripping when a pump turns on when grid down.
Click to expand...
How about a victron solution?

4x 10kva units for 40kva, crazy surge rating(im told) 100a passthrough per inverter, and you can keep your strings hooked up to your existing inverters and just ac couple.
 
user2562 said:
Unfortunately I do not have good load monitoring. I agree, this is probably excessive, but required to get 200A passthrough using the HESP. I don't want the high inrush stuff to trip.
Click to expand...
Based off my experience with the my ASF, you'll have minimal surge issues. It handled my deep well pump, air compressor, miter saw, table saw, etc just fine.
user2562 said:
If I did Growatt SPH10k I would probably do 6x for 60,000 250A since each unit has grid passthrough of 63A, allowing 3x to get ~190A passthrough. I can deal with maybe tripping when a pump turns on when grid down.
Click to expand...
Since you mentioned 10k... I recently upgraded my ASF to 2 ASP's in parallel. I haven't pushed them much past 15KW output for sustained periods yet but I've been impressed so far. I'm able to run my ~1,000 sq ft house with extremely minimal concerns regarding load management. You might want to check out the ASP.
 
42OhmsPA said:
Based off my experience with the my ASF, you'll have minimal surge issues. It handled my deep well pump, air compressor, miter saw, table saw, etc just fine.

Since you mentioned 10k... I recently upgraded my ASF to 2 ASP's in parallel. I haven't pushed them much past 15KW output for sustained periods yet but I've been impressed so far. I'm able to run my ~1,000 sq ft house with extremely minimal concerns regarding load management. You might want to check out the ASP.
Click to expand...
He is grid tied and will export to the grid so i don't think the asp will work
 
1201 said:
He is grid tied and will export to the grid so i don't think the asp will work
Click to expand...
Exactly. Really wanted to do the ASP as I'm mounting indoors and price is unbelievable. But no ability to export to grid and utilize batteries when grid is up is a problem.

Confirmed with Borick -- "With item 01 set to UTI, the battery cannot be used unless the grid is turned off.
That's because item 01 refers to the priority utility > PV > battery, and will only allow the battery to supply power to the load if the utility is not available" If there's a way to do it, Borick doesn't seem to know how.
 
Last edited:
1201 said:
How about a victron solution?

4x 10kva units for 40kva, crazy surge rating(im told) 100a passthrough per inverter, and you can keep your strings hooked up to your existing inverters and just ac couple.
Click to expand...
42OhmsPA said:
CURRENTlty 6 in stock.
Click to expand...

Will look into this. But my existing grid tie inverters will go down when grid goes down, so for extended grid down I would lose solar?
 
1201 said:
He is grid tied and will export to the grid so i don't think the asp will work
Click to expand...
Yep I covered that the ASP will grid feed no problem. It was the post you marked off topic in your thread.
 
Also borick is wrong on not being able to use the batteries since you can manually set battery usage. It will switch modes to use the batteries and then switch back when the time elapses from the schedule you set.
 
user2562 said:
Exactly. Really wanted to do the ASP as I'm mounting indoors and price is unbelievable. But no ability to export to grid and utilize batteries when grid is up is a problem.

Confirmed with Borick -- "With item 01 set to UTI, the battery cannot be used unless the grid is turned off.
That's because item 01 refers to the priority utility > PV > battery, and will only allow the battery to supply power to the load if the utility is not available" If there's a way to do it, Borick doesn't seem to know how.
Click to expand...
Enable the timers in setting 46 (timed battery charge) and 53 (timed battery discharge) might be one way, enabling an automation in SA would probably be simpler.
 
42OhmsPA said:
Enable the timers in setting 46 (timed battery charge) and 53 (timed battery discharge) might be one way, enabling an automation in SA would probably be simpler.
Click to expand...
You have me back at trying to figure out how make the ASP work. So tempting.

Use SA to change the mode, and ASP responds pretty quick to a change in mode (UTI to SBU, whatever else is needed to use battery instead of grid)
 
user2562 said:
Will look into this. But my existing grid tie inverters will go down when grid goes down, so for extended grid down I would lose solar?
Click to expand...
If you AC couple they won't even know when the grid is down. They'll keep operating as normal
 
Crowz said:
Yep I covered that the ASP will grid feed no problem. It was the post you marked off topic in your thread.
Click to expand...
Those settings are only on the asp that i know of, not the hesp that's why i marked it off topic
 
Crowz said:
Also borick is wrong on not being able to use the batteries since you can manually set battery usage. It will switch modes to use the batteries and then switch back when the time elapses from the schedule you set.
Click to expand...
But will it discharge batteries to the grid (in addition to loads) during that time? Didn't see a setting to prevent that.

Still think I could make it mostly with with SA but I might be inviting headache.
 
1201 said:
Those settings are only on the asp that i know of, not the hesp that's why i marked it off topic
Click to expand...
Yep figured that but I figured you had read it before marking it off topic and but then said :

He is grid tied and will export to the grid so i don't think the asp will work
Click to expand...
 
user2562 said:
But will it discharge batteries to the grid (in addition to loads) during that time? Didn't see a setting to prevent that.

Still think I could make it mostly with with SA but I might be inviting headache.
Click to expand...
It should run on the batteries during that time and not backfeed during the schedule from what it says and then when the schedule ends it should flip back to the grid feed setup. I don't back feed so I can't test that or I would.
 
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