Moving forward with solar

[SunCatcher]

After much soul searching and pulling out of hair things are slowly coming together. I had no idea just what I signed up for. Because of the internet and places like this I have most of the answers I needed to pull this off. So there are just a few questions left. The system uses the Solark 12K inverter and 28 330 watt panels (I think 37 volt?) I am in oregon if that is relevant.

#1 My array is 350 feet from the house and the D.C. has three strings at about 370, 340 and 340 Volts each. Solark does not show a DC shutoff going into the house. I could be wrong but I think it is because most systems are roof mount and very few are 350 feet away from the house. Thus I have to run my array at high voltage to keep the wiring size down. Solark does show the knife edge going from the inverter to meter (AC) that prevents Inverter from backfeeding into the grid during an emergency. I also shows the emergency shutdown. There is no mention anywhere with Solark showing a DC knife edge shutoff.

My concern is that during an emergency the fire fighting crew will think that they have shut off the electricity in the house and yet there are three DC circuits running dangerous high voltage into the house to the Inverter. So does anyone have information on this. The county here is low staffed due to covrid and will be reopening soon but I am trying to move forward if at all possible. Any information on this would be very much appreciated.


Les

 

[WYtreasure]

WoHoo a new member to the "Hair Pulling Party.

Welcome!?

 

[SunCatcher]

Next question.... The inverter can have a maximum continuous load of 50 amp going through it. I am planning my "Priority" panel and should we ever have a long term grid outage I must have the ability to use my shop at least have the ability for repairing equipment etc. I recognize that a 12 K system with 9000 watts of panels does not give you the ability to operate "business as usual" So as I look at the priority panel the curcuits that I would like to run if at all possible are

-lights and basic household plugs which run your computers etc
- fridges and freezers
- well pump.... we must have water, deep well @30Amp
- hot water tank.... at the end of the day someone needs a shower
- shop... the breakers for the air compressor can be left off most the time

We do have battery storage for up to one week and possability to hook up a generator. I hope that I am not trying to put too much on the priority panel but the reality is we need everything there daily except the shop which is more emergency and not needed often. So my question is am I being realistic and secondly I have a concern.... My shop air compressor uses 14.5 amps per leg for 29 amps. I have a stick weld that uses a lot more than that when it is turned up. Not sure when lower but the issue is this. If the shop is on the priority panel I think that means that every time I use the welder that that power is going through the Inverter. It is not uncommon to have the welder and the air compressor running at the same time. No issue when on the grid... but I think that if that power was going through the Inverter which means that even if I turned of the house I am still maxing out the allowable electricity able to go through the inverter.

I am wondering if I should use a switchable transfer switch so that my shop is normally fed with grid power and then when the grid is down... if we need the shop then we could manually switch to the Inverter. That way the shop daily use does not go through the Inverter. I think this makes sense but I am a newby at this.

Les

 

[SunCatcher]

ROFLOL.... thank you for the welcome. This has been a very humbling experience so far. I have the ability to do this... but am very lacking in knowledge

 

[WYtreasure]

You're welcome for the welcome.
Someone smarter than me will help you so much more though.

Do you have pics of the electrical panels you mentioned?
Do you have a clamp meter to find out how much surge your compressor, pump and other items produce?

System Energy Audit and Sizing Spread Sheet

To get the spreadsheet, click on the orange button at the top of this page. This sheet is intended to help you plan your system. Fill it out down to the last decimal place, look at the results..... and then make your best guess;) Notes...

diysolarforum.com

 

[Hedges]

Many inverters have DC disconnect internal, which leaves wires to them live.
Having PV wire in metal conduit where routed inside house to inverter should keep it safe.
Mine is mounted on outside wall, an all rigid conduit except for liquid tight flexible metallic for last connection.

There are 600VDC 30A rated 3-pole switched from Square D. That could open one leg of each array. But does SolArk have PV array grounded on negative, or ungrounded?
Some breakers are rated up to such voltage, typically with multiple poles. If you find one which is 250V per pole, then 2 poles could interrupt both positive and negative. Six poles ganged together with a wire through the handle would shut off all at once.

Midnight has "Birdhouse" remote shutdown which sends a signal to remote-trip breakers. That could work with multiple circuits and a single shutdown lever.


You might set up priority load control, like a relay so when one load turns on it shuts off another. Well pump vs. A/C for instance.
Shop tools more likely to do manually, since they don't have low level control signals.
Compressor uses 14.5 amps per leg for ... 14.5 amps at 240V. Sol-Ark is a 120/240V inverter, right? Some systems are limited in what they can deliver as imbalanced 120V current by a transformer. Some have no transformer at all, just inverter switching supply per leg.

Welder - if buzz box it uses high leakage inductance to limit short-circuit current. Have to see if inverter is happy with large phase shift and moderately high currents.
If inverter welder, probably has another kind of poor power factor, pulses of current near peak voltage.

Some people have blown up some inverters with some welders. But were able to use a different brand inverter.

 

[SunCatcher]

They are the Aqua Blu as per attachment. I hooked my meter to a few circuits and found my air compressor is an energy hog at 14.5 per leg. When I tried the oven my numbers seemed way low at 3.4 per leg for the oven and .5 per leg for the two burners turned on high. I am going to recheck those. The compressor matches with the manufacturers tag. Im not pulling the stove any time soon

 

[SunCatcher]

Many inverters have DC disconnect internal, which leaves wires to them live.
Having PV wire in metal conduit where routed inside house to inverter should keep it safe.
Mine is mounted on outside wall, an all rigid conduit except for liquid tight flexible metallic for last connection.

There are 600VDC 30A rated 3-pole switched from Square D. That could open one leg of each array. But does SolArk have PV array grounded on negative, or ungrounded?
Some breakers are rated up to such voltage, typically with multiple poles. If you find one which is 250V per pole, then 2 poles could interrupt both positive and negative. Six poles ganged together with a wire through the handle would shut off all at once.

Midnight has "Birdhouse" remote shutdown which sends a signal to remote-trip breakers. That could work with multiple circuits and a single shutdown lever.


You might set up priority load control, like a relay so when one load turns on it shuts off another. Well pump vs. A/C for instance.
Shop tools more likely to do manually, since they don't have low level control signals.
Compressor uses 14.5 amps per leg for ... 14.5 amps at 240V. Sol-Ark is a 120/240V inverter, right? Some systems are limited in what they can deliver as imbalanced 120V current by a transformer. Some have no transformer at all, just inverter switching supply per leg.

Welder - if buzz box it uses high leakage inductance to limit short-circuit current. Have to see if inverter is happy with large phase shift and moderately high currents.
If inverter welder, probably has another kind of poor power factor, pulses of current near peak voltage.

Some people have blown up some inverters with some welders. But were able to use a different brand inverter.

Hedges wrote:
Many inverters have DC disconnect internal, which leaves wires to them live.

-Correct... Mine has that.

There are 600VDC 30A rated 3-pole switched from Square D. That could open one leg of each array. But does SolArk have PV array grounded on negative, or ungrounded?

Turns out there was one of them sent with my system... however here is where the hairpulling happens for me. The Solark drawings all show that I need a knife edge shutoff on the A/C between the 60 Amp feed breaker and the Inverter positioned near the meter and also the emergency shutdown switch. But when I contacted them they said that those drawings are mostly for roof mount systems. What Solack does not have are good ground mount drawings and they were not able to advise on the DC side of things

So where I am struggling... do I need the A/C shutoff between the breaker feed and the Inverter to prevent backfeeding the grid AND a D/C knife edge shutoff as we are discussing. . And if I do need the D/C shutoff does it have to be within 15 feet of the meter... In my case I would have to add another 50 feet of #4 gauge wire. I would really hate to see that as I am already about 400 feet of wire to the Inverter. Or am I allowed to have it on another side of the house with a sigh by the meter. I have seen those signs so that must be possible.

Hedges wrote

But does SolArk have PV array grounded on negative, or ungrounded?

I was told to put three circuits of two 4 gauge wires for each circuit for six wires total. The solar mount system is grounded with grounding rods. So if I understand correctly we have three circuits coming in to the Inverter and the neutrals are picked up from the house. I'm a carpenter and work around electricity all the time but am not an electrician. The Inverter wiring diagrams all show that to be the case.

As far as welders go... I do use the big buzbox but I have a mig I would likely use when off the grid.

Hedges wrote

You might set up priority load control, like a relay so when one load turns on it shuts off another. Well pump vs. A/C for instance.
Shop tools more likely to do manually, since they don't have low level control signals.
Compressor uses 14.5 amps per leg for ... 14.5 amps at 240V. Sol-Ark is a 120/240V inverter, right? Some systems are limited in what they can deliver as imbalanced 120V current by a transformer. Some have no transformer at all, just inverter switching supply per leg.

I want to check out those load controllers... I watched a youtube on that very thing Solar is VERY sensative to having balanced loads on each leg. If one legs goes over it shuts down for a couple minutes and restarts. I will look into priority load control.

Thank you SO MUCH for your help

Les

 

[Hedges]

Compressor may well draw kVA above kW ratings, due to inductive load. I still don't know how inverters deal with that.

There is a video of DC arc welding with PV panels.

I wonder if a motor-generator would be safest way to isolate nasty things like welders from the inverter. Maybe get a rotary phase converter, which could also feed 3-phase shop tools, and power welder off two legs? I have a VFD for 2 HP pool pump, and the waveforms it produces seem to upset my GT PV inverters (but not my transformer-type battery inverters.)

Back around 2003, PG&E required visible blade knife switch to disconnect GT PV inverter from breaker panel, so they would know for sure it was isolated. Later, they wrote that such switch was optional; they could yank meter (leaving house without any power) if necessary. So requirement for knife switch depends on your utility.

PV array structure and frames are to be grounded back to ground of the system, maybe also with ground rods at array.

What I'm referring to is, does PV array have negative wire tied to ground? My earlier transformer-type GT PV inverters grounded it through a 1A fuse. If fuse blew, they recognized a ground fault had occurred and shut off. Most PV panels are happiest with negative ground, all cells biased positive with respect to ground (voltage is felt by them as an E-field between cell and frame, dirt, water. Opposite polarity could cause something known as PID, Potential Induced Degradation). Some panels, notably early SunPower, were designed for slower degradation when exposed to sun, but turned out to degrade fast due to PID. Solution was positive ground. Today, most panels should be "PID free", which really means reduced rate of PID.

Transformerless inverters, popular today for lower cost, higher efficiency, lighter weight, smaller size, have ungrounded PV array. Your 380V could be +190V at one end, -190V at the other. Two-pole disconnect is recommended.

I like to isolate both PV leads before working on the wiring. So I shut off equipment to interrupt current, then open fuse holders, then unplug both ends of MC cable. Checking voltages along the way to confirm current flow has stopped and then circuit is isolated.

"Neutral" probably isn't a concept for your PV array. There is positive or negative, and ground wire. Positive or negative may or may not be grounded. If it does have a ground-fault fuse, in the event that blows (due to a short at some other voltage point in the array, that "grounded" leg will suddenly become hot.

But once converted to AC, sure, "Neutral" is the grounded neutral of your house wiring, and L1 and L2 are relative to that.

DC shutoff probably doesn't have to be near meter. AC shutoff would be. In the case of rooftop PV, "Rapid Shutdown" to reduce array voltage < 80V would probably be near meter. Simply interrupting AC accomplishes that for GT PV (but not for hybrid with batteries.) The DC shutoffs tend to have remote trip circuits.

 

[SunCatcher]

Had a good day yesterday but did run into one "hopefully" small snag. I am going to use an Inverter bypass and have now decided to use a bypass for the shop as well. The Inverter bypass for two reasons

- If I live long enough the Inverter will fail. When It does I want the ability to bypass it to the grid without doing a hardwire. I also want the freedom to have the solar down for a few weeks while I send the Inverter out for rebuild... or scramble to find $10 k to upgrade

-Second reason is when I am wiring my priority panel and my water pump, hot water tank, not to mention all important plugs and lights etc. is down, while waiting for wiring to be finished... then find out the county office is shut down due to covrid

So I mounted the bypass panel with the breakers installed only to realize that there is no Ground bus. Can I simply install a bus or do I need another box.

Here is a picture of my bypass.... the box is a Siemens 125A part # E0816ML1125SCU which is described as a Main Lug Load Center
Is there a better box? and if so what is it? Part numbers etc?

I am striving to finish a few circuits to completion and am more optimistic about the project since I now have more answers than questions which has really saved on the hair pulling

So can I simply add a ground bus bar?

Les

 

[SunCatcher]

In the picture on the left hand side you will see a "G" in black marker. That is grid tie for the Shop. The "I" on the RH side is for Inverter for when the grid is down. That way My shop with the welders and compressors are running directly from the grid without overloading the Inverter. When we loose the grid I then have the option to switch the shop over to the Inverter.

 

[WYtreasure]

Here is a picture of my bypass.... the box is a Siemens 125A part # E0816ML1125SCU which is described as a Main Lug Load Center
Is there a better box? and if so what is it? Part numbers etc?
So can I simply add a ground bus bar?

Can you confirm the part # please. I can't find your product. Many of Siemens boxes that come without ground buss bar can accept one.
Are you in the USA? Last I checked Oregon was still attached to us.

I purchased this recently. I do not think it will work for you but something similar might.

SIEMENS GF222N 60 Amp, 2 Pole, 240-Volt, 3 Wire, Fused, General Duty, Indoor Rated ​

 

[svetz]

After much soul searching and pulling out of hair things are slowly coming together.

Welcome to the forums!

330 watt panels (I think 37 volt?) I am in oregon if that is relevant.

The Sol-Ark is a string inverter so you'll be putting your panels in series and parallel. The Sol-Ark manual has instructions for that, but if you want to know more see:

• What does it mean to have solar panels in parallel and series?
• Figuring out how many panels in series and parallel based on your MPPT

Each panel in series adds the voltage, so 7 in series is 7x37=260V, so be careful!

#1 My array is 350 feet from the house and the D.C. There is no mention anywhere with Solark showing a DC knife edge shutoff.

The good news is you can add a cut-off anywhere you like. Have one near the house and the panels if you like.

My concern is that during an emergency the fire fighting crew will think that they have shut off the electricity in the house and yet there are three DC circuits running dangerous high voltage into the house to the Inverter.

The main concerns are for when they're on the roof, then the NEC has rapid shutdown requirements for this. Check with your local codes, but AFAIK, not needed for ground mounts.

IMO, the absolute kindest thing you can do for fire-fighters (and yourself) is to label the hell out of everything. Put a disconnect switch on the house as you mentioned and label it. Here's a link to the NEC labels: https://www.dli.mn.gov/sites/default/files/pdf/solar_labelguide.pdf.

The inverter can have a maximum continuous load of 50 amp going through it.

That's 50 amps of 240V, but it's 25 amps per leg. If you have high amp loads on 120V circuits you might need to do some rebalancing.

I am planning my [critical circuits] I would like to run if at all possible are lights, house plugs, fridge/freezer, well pump (30 amp), hot water tank, air compressor

The bad news is the pump may draw well over 30 amps at startup, it's known as in-rush current and your LRA (Locked Rotor amps) is a good indicator. You may need a softstarter or convert to a DC pump and use a battery to provide the umph to get it going. Ditto the air compressor. The sol-ark will go over the 50 amps for short periods, but without knowing the actual in-rush it's a bit a crap shoot. You can measure in-rush with a clamp meter that has that function.

... am I being realistic ...

Sure, probably not running the hot water tank at the same time as the compressor and the pump. I don't even run through a critical circuits panel, I have mine as the direct feed to the house and I control what I want on/off at the breaker. This way if my batteries are full and I'd otherwise be wasting solar power I can turn on the EV charging or hot water tank.

... every time I use the welder that that power is going through the Inverter. It is not uncommon to have the welder and the air compressor running at the same time.

Can you convert to DC welding since you have a battery?

I am wondering if I should use a switchable transfer switch so that my shop is normally fed with grid power and then when the grid is down... if we need the shop then we could manually switch to the Inverter.

The Sol-ark has a built in transfer switch that might suit your needs there.

...Someone smarter than me will help you so much more though....

Oh crap, they got me... ; -) Pressure's on I guess... well, sort-of ....trust... but be sure to verify ; -)
Update: Whew! Hedges replied too! ; -)

Hope that helps!

 

[WYtreasure]

Told ya so:

Oh crap, they got me... ; -) Pressure's on I guess... well, sort-of ....trust... but be sure to verify ; -)
Update: Whew! Hedges replied too! ; -)

? You're happy now Les.

 

[SunCatcher]

You guys are SO AWESOME!!!! Thank you SO MUCH. Ihave not seen anythiung about a "built in transfer sawitch" Only that you need to add an external one.

 

[svetz]

I have not seen anythiung about a "built in transfer switch" Only that you need to add an external one. It's been years since I looked into them so this could be all wrong.... but as I recall in the diagram the AC load out was normally connected to the AC In/out, but on a power failure would switch over to the inverter. As long as the amps drawn across the breaker don't exceed its rating when the grid is up I don't see it being a problem (although some disconnects to isolate/bypass the inverter for maintenance sounds wise).

 

[SunCatcher]

It's been years since I looked into them so this could be all wrong.... but as I
recall in the diagram the AC load out was normally connected to the AC In/out,
but on a power failure would switch over to the inverter. As long as the amps drawn
across the breaker don't exceed its rating when the grid is up I don't see it being a
problem (although some disconnects to isolate/bypass the inverter for maintenance
sounds wise).

On this Inverter it states

Maximum Passthrough AC current 50Amps. The key is "passthrough" So if I understand that correctly that means that you cannot "Pass more than 50 AMps" through the Inverter EVEN WHEN the grid is up and running. So I think I need that Shop bypass. I think I will ask Solarck just to be sure. Will post the findings.

 

[SunCatcher]

Hey... I am slow but I am catching on. Duh... the reason that is says maximum "passthrough" is 50 Amps is vey simple.... The Inverter is fed by a 60 amp breaker and it obviously needs a bit for it to run so You have reached your limit. You cannot use more grid power than you are feeding Therefore if I want to have the shop for emergency only when the grid is down I therefor need to have a transfer switch so it runs on grid for daily use. I will admit it... I'm an armature but I am catching on.

Les

 

[WYtreasure]

Hey... I am slow but I am catching on. Duh... the reason that is says maximum "passthrough" is 50 Amps is vey simple.... The Inverter is fed by a 60 amp breaker and it obviously needs a bit for it to run so You have reached your limit. You cannot use more grid power than you are feeding Therefore if I want to have the shop for emergency only when the grid is down I therefor need to have a transfer switch so it runs on grid for daily use. I will admit it... I'm an armature but I am catching on.

Les

I'm more of an armature than you and really wish I knew what you just said. Seriously.

 

[svetz]

... really wish I knew what you just said. Seriously....

I think it was just following up on what I suggested in #16. Seems the "AC load out" on the sol-ark is "only" rated 50 amps continuous.

When the grid is out it would be okay for the AC load out to power the shop since it won't deliver more than 50 amps.

But, if in normal operation (e.g., grid up) the shop draws more than that it would constantly be tripping the sol-ark breaker. So, for normal operation, a bypass is needed for the shop.

Let's look at the case where it would work, say the shop subpanel was a maximum of 45 amps and the case where it wouldn't work:

If it were less (say 45 amps) then it could be wired like this: ​ Here the built in transfer switch handles the shop.

But... if the shop subpanel is 100 amps. Then they need to bypass so they have full power when the grid is available. ​

Note: only 1 phase is shown in the diagram for simplicity with a DPDT. In practice, you'd want one switch flick to change L1 & L2 simultaneously ...possibly this.

Hope that helps!