3 phase inverter recommendations

[Gilligan]

I own a screen printing shop and use about 5,000KW/Month ($600 electric bill).

Long term goal is to end up at about net 0 electric bill. I hope to be buying a Tesla Model 3 in the next year or so which I would charge at work.

I'm ok with building as I go as prices are dropping and obviously I'm not ready to drop the full cost of a full system today.

I'm in a 3 phase commercial building and have several devices that require 3 phase, I also own the building.

I'm in South Louisiana and have full sun (which is killing me with heat on the metal roof), low pitch roof though it does slope the wrong direction. Overall roof size is 4,000 sqft so plenty of room.

So, my original thoughts were to buy an inverter to grow into at my long term goal but in looking around I'm having a hard time finding what I need. I don't have 480 but I have 208/220 coming in and I'm using very close to 100 amps during the day... I use almost nothing at night (just computers and HVAC are running but they aren't running very hard).

Now I'm wondering if I could use micro inverters with a 3 phase system because that might be the better solution as well as allow me to buy as I need.

Is this incorrect thinking? What are you guy's thoughts?

Thanks!
Gilligan

[bcroe]

If you want to save money and avoid additional maintenance, check with your power co
about net metering and avoid batteries. That amount of KWH might take 100 to 200
panels, depending on size and your sun situation. Panels will not produce much under
clouds or snow, but net metering will allow operating to make a good average.

The most economical solutions use conservation. Find out just how your 5000KWH
are consumed. If there is a big air conditioning load, check the AC unit efficiency.
Older units might have a SEER of 13, latest are 30 SEER which is a huge savings.
Motor drives have improved too, and lighting. good luck, Bruce Roe

[ButchDeal]

I own a screen printing shop and use about 5,000KW/Month ($600 electric bill).

5,000kWh/month (need an h) or better written as 5MWh/month

Long term goal is to end up at about net 0 electric bill.

you should look at net metering then.

I'm ok with building as I go as prices are dropping and obviously I'm not ready to drop the full cost of a full system today.

Solar doesn't expand very easy. Sort of like trying to buy a 4 cylinder car and latter expand to a V8...

I'm in a 3 phase commercial building and have several devices that require 3 phase, I also own the building.

3Phase is no big deal for net metered systems.

I'm in South Louisiana and have full sun (which is killing me with heat on the metal roof), low pitch roof though it does slope the wrong direction. Overall roof size is 4,000 sqft so plenty of room.

So, my original thoughts were to buy an inverter to grow into at my long term goal but in looking around I'm having a hard time finding what I need. I don't have 480 but I have 208/220 coming in and I'm using very close to 100 amps during the day... I use almost nothing at night (just computers and HVAC are running but they aren't running very hard).

So you need a grid tie that works with 208V like one of these (most manufacturers have them):

https://www.solaredge.com/sites/default/files/se-three-phase-us-inverter-208V-setapp-datasheet.pdf

[Gilligan]

I was never thinking of anything other than Net Metering, sorry I didn't make that clear.

Yes, the building is fairly inefficient in insulation... but I also run a giant "pizza oven" for curing t-shirt where I have to run the panels at 1,000*F Plus there are several other sources of heat in the production of t-shirts. The AC runs CONSTANTLY from sun up to practically sundown and still doesn't keep up. I'm HOPING that all the panels on the roof would also help with shading the roof some.

This is also with us not really running production constantly... as we grow and our printing utilization time goes up then we will consume even more energy and produce even more heat.

ButchDeal , I've looked at those inverters... my problem is that I easily consume on average 75 amps if my calculations are correct. I know I have personally monitored about 105 amp draws with a clamp meter when EVERYTHING is running (air compressor cycles on and off so that's not constant and we don't run the pressure washer and other heavy draw appliances all the time). Those inverters say they have a max current output of 40amps. That won't be enough and I'll still be drawing off the grid all day long. Would I need/be able to link of two of them?

By expand, I meant just adding panels when the budget allows. Buy say, 20 panels to start with, then add another 20 or so later and then maybe another 20 or so later. If planned properly shouldn't this be feasible?

[ButchDeal]

I was never thinking of anything other than Net Metering, sorry I didn't make that clear.

ButchDeal , I've looked at those inverters... my problem is that I easily consume on average 75 amps if my calculations are correct. I know I have personally monitored about 105 amp draws with a clamp meter when EVERYTHING is running (air compressor cycles on and off so that's not constant and we don't run the pressure washer and other heavy draw appliances all the time). Those inverters say they have a max current output of 40amps. That won't be enough and I'll still be drawing off the grid all day long. Would I need/be able to link of two of them?

By expand, I meant just adding panels when the budget allows. Buy say, 20 panels to start with, then add another 20 or so later and then maybe another 20 or so later. If planned properly shouldn't this be feasible?

Well with Net metering the inverter doesn't power your loads directly it slow and steady back feeds the grid. On top of that you can also have multiple inverters. There are larger ones but they are at higher grid voltage, you only have 208V you stated but if you have higher voltage you can kick up to higher ones like these:
https://www.solaredge.com/sites/defa...-datasheet.pdf

also is that 105a draw on all three legs or just one or two?

[Gilligan]

Well with Net metering the inverter doesn't power your loads directly it slow and steady back feeds the grid. On top of that you can also have multiple inverters. There are larger ones but they are at higher grid voltage, you only have 208V you stated but if you have higher voltage you can kick up to higher ones like these:
https://www.solaredge.com/sites/defa...-datasheet.pdf

also is that 105a draw on all three legs or just one or two?

Ok, I didn't realize you could have multiple inverters.

So it really is seeming more and more expandable... what am I missing?

I can't recall how I calculated that... it's been some years since I checked my load draw. I'll pop the panel next week and run some checks while we are operating and see what I have going on more precisely.

I'm gonna go read about pros and cons of microinverters but from what I've been reading for the past hour or so it seems like I could run microinverters and still combine it to make 3 phase. This makes the idea of expansion enticing again.

I know that microinverters are pricey to some degree, because if I have 60 panels at $150 per inverter then I'm sitting at $9k... but at the end of the day, wouldn't a few inverters get up to about that price range anyway and with this not only do I have incremental growth/expense, I also don't have a single point of failure (technically a few). I mean, I only know the basic pros and cons as I glanced over them when I first learned about them but dismissed them as too costly or not applicable because of my 3 phase situation. So maybe I'm missing something more important.

[Mike90250]

I'd remove those big heating ovens from the air conditioned space. Somehow. or build a containment room around them and vent it seperatly.

[ButchDeal]

Ok, I didn't realize you could have multiple inverters.

So it really is seeming more and more expandable... what am I missing?

I can't recall how I calculated that... it's been some years since I checked my load draw. I'll pop the panel next week and run some checks while we are operating and see what I have going on more precisely.

I'm gonna go read about pros and cons of microinverters but from what I've been reading for the past hour or so it seems like I could run microinverters and still combine it to make 3 phase. This makes the idea of expansion enticing again.

I know that microinverters are pricey to some degree, because if I have 60 panels at $150 per inverter then I'm sitting at $9k... but at the end of the day, wouldn't a few inverters get up to about that price range anyway and with this not only do I have incremental growth/expense, I also don't have a single point of failure (technically a few). I mean, I only know the basic pros and cons as I glanced over them when I first learned about them but dismissed them as too costly or not applicable because of my 3 phase situation. So maybe I'm missing something more important.

Well enphase mase 208V compatible micros but they are not 3 phase, they are just single phase 208V. The inverters I showed you handle 3 phase and would tie into 3 phases and feed all three phases with a single breaker.
You can use either and both are expandable but expansion is not that great of an idea as you would need multiple permits, multiple inspections, and interconnect agreement applications etc. It would be a lot cheaper as a single unit with a loan than multiple expansions.

This isn't really a DIY type system so you should get a few quotes and go from there.

[solarix]

Use SunnyBoy 7.0 inverters. They work on any AC voltage you got - Can deliver 32 Amps @ 208V (same as the "larger" 7.7kW) Use one on each phase to stay balanced. Has built in internet now as well so you can monitor them all at once via the online portal. We did a commercial system like this last year using nine inverters and 240 panels - it cranks out a max of 156A, 3ph for 5 hours a day. Remember that with 3phase, 32A (AC output of 7kW inverter) x 1.73 (sqrt of 3) x 1.25 (continuous ampacity derating) = 69Amps per set of three 7.7kW inverters.

[ButchDeal]

Use SunnyBoy 7.0 inverters. They work on any AC voltage you got - Can deliver 32 Amps @ 208V (same as the "larger" 7.7kW) Use one on each phase to stay balanced. Has built in internet now as well so you can monitor them all at once via the online portal. We did a commercial system like this last year using nine inverters and 240 panels - it cranks out a max of 156A, 3ph for 5 hours a day. Remember that with 3phase, 32A (AC output of 7kW inverter) x 1.73 (sqrt of 3) x 1.25 (continuous ampacity derating) = 69Amps per set of three 7.7kW inverters.

Using three inverters instead of a single 3 phase inverter is a poor way to do a large install...

[Gilligan]

I'd remove those big heating ovens from the air conditioned space. Somehow. or build a containment room around them and vent it seperatly.

This comment from a Moderator?!

I mean, huh?

[Gilligan]

Use SunnyBoy 7.0 inverters. They work on any AC voltage you got - Can deliver 32 Amps @ 208V (same as the "larger" 7.7kW) Use one on each phase to stay balanced. Has built in internet now as well so you can monitor them all at once via the online portal. We did a commercial system like this last year using nine inverters and 240 panels - it cranks out a max of 156A, 3ph for 5 hours a day. Remember that with 3phase, 32A (AC output of 7kW inverter) x 1.73 (sqrt of 3) x 1.25 (continuous ampacity derating) = 69Amps per set of three 7.7kW inverters.

I think this or a maybe a 7.7 (any reason not to step up to the 7.7 for the little extra money they ask?) as it would be economical at less than $1,800 and would let me run 3 strings adding to just one leg of my power right now right? Then I could add more inverters later? Do I understand that correctly?

This would let me run twelve 325w panels in series on each string allowing me a total of 36 per inverter... this would equal over 100 if I put together three of these.

Cost would be like $2,500 per string plus the ~$2,000 for the inverter. I could start with $5k and then add another string at $2.5k or so when I can afford it.

I don't see why I shouldn't DIY this? I've been around electricity all my life and have HUGE respect for it... I don't remember NOT knowing how to solder. My father owned a tv repair shop before I was born and segwayed that into being the first satellite dealer in the state. I recall a time when we had to hand crank fiberglass dishes and I remember being so young that I thought when a bird landed on the LNB that I would go inside and see the shadow of the bird on the TV. LOL

Only thing I'm not really good at is carpentry and I have some friends to help with that.

[Mike90250]

......
Yes, the building is fairly inefficient in insulation... but I also run a giant "pizza oven" for curing t-shirt where I have to run the panels at 1,000*F Plus there are several other sources of heat in the production of t-shirts. The AC runs CONSTANTLY from sun up to practically sundown and still doesn't keep up. I'm HOPING that all the panels on the roof would also help with shading the roof some.......

I'm addressing deficiencies that haven't been addressed yet.

> the building is fairly inefficient in insulation
> I also run a giant "pizza oven" for curing t-shirt where I have to run the panels at 1,000*F
> Plus there are several other sources of heat
> I'm HOPING that all the panels on the roof would also help with shading the roof

These 4 items should be resolved before you can hope to reduce your energy bill. Throwing solar panels at it, is treating it like a boat - " A hole in the water to be filled with money".

Insulation - every energy guidebook starts with upgrading the insulation. Go ahead and ignore that and buy even more panels.

If you don't vent the excess heat indoors, you don't have to spend 4x the energy to remove it.

Other heat sources - it's up to you. Go ahead and light the chafing dish and put it in the walk-in cooler. The cooler will never catch up with the heat source. Same with your building.

Go ahead and hope, it's your $ flying out the door. I'm just spending my time typing. This is the solar forum of fewer illusions. There are many places on the internet where you can always get an Amen.

[solarix]

This would let me run twelve 325w panels in series on each string allowing me a total of 36 per inverter... this would equal over 100 if I put together three of these.
Cost would be like $2,500 per string plus the ~$2,000 for the inverter. I could start with $5k and then add another string at $2.5k or so when I can afford it.
.

About 24 325w panels per 7kW inverter is going to max them out. Yes, can start with one inverter and add on if your AC wiring and POCO interconnect agreement will plan for that.

[bcroe]

Listen to Mike90250, that advice will get results. Some local professional help may be
required in arranging to vent hot processes outside, and other things. Bruce Roe