My DIY XW Pro System

[jzampieron]

Thoughts on the electronics install for my 31 panel Aptos 370W system. This is meant to be a grid-sell net-metered w/ battery & generator backup.

Dual MPPT 100-600 w/ RS and Dual XW Pros.

Strings will be 10s2p and 11s1p.

AC Panel on the Right is a grid-tied sub-panel and AC panel on the left is a critical load panel.

Rack in the front is an EG4 6x 5kWh Lifepower4 Rack (30kWh).

The mounting is 1/2" cement board over 3/4" plywood which is painted w/ Intumescent Paint. Looks good and makes it much more fire resistant.

Need to go out and grade the field for the Iron Ridge racking and get the panels set... will post photos on that when finished.

Note: Panels are not connected yet. Hence the wires hanging out of the Disconnect RS. Running grid-tied backup while I finish the excavation.

100% of the install done by me & my wife.

 

[faccnator]

Looks great! More pics please!

 

[jzampieron]

I have a ton of video of that electrical work. Like probably 100 hours or more. Needs to get edited into something watchable and not just me turning screws.

I just finished augering the holes in my yard for the ground mount poles. The first round of cement comes wednesday. Next weekend and throughout the week I'll be standing up the racking.

I'll post some photos of the holes in the yard in a day or so.

 

[jzampieron]

Project is in full swing. My body is sore all over from loading bags of quikrete into the mixer.

Here's a photo of the ground mount array front rail ready for concrete.

 

[jzampieron]

Front Pipe with partial concrete. Back Pipe ready for concrete.

 

[JBertok]

Looks awesome, nice work. I always love to look at the insides with the covers off, but I can tell from the photos that it might be worth mentioning the PDP isn't technically rated for 600V and it looks like your PV SPDs are mounted in it. That's also why putting array breakers inside the PDP are only officially supported for the MPPT 60/150, and where the Disconnect RS is suggested to be used to externally provide PV disconnect, and rapid-shutdown when paired with TS4-F units.
The gutter under everything is great - nice choice.
Is the chargeverter for your generator (I see the AGS) to avoid dealing with the dreaded AC2 problems?

 

[jzampieron]

Looks awesome, nice work. I always love to look at the insides with the covers off, but I can tell from the photos that it might be worth mentioning the PDP isn't technically rated for 600V and it looks like your PV SPDs are mounted in it. That's also why putting array breakers inside the PDP are only officially supported for the MPPT 60/150, and where the Disconnect RS is suggested to be used to externally provide PV disconnect, and rapid-shutdown when paired with TS4-F units.
The gutter under everything is great - nice choice.
Is the chargeverter for your generator (I see the AGS) to avoid dealing with the dreaded AC2 problems?

There's no 600V DC in the PDP. Only in the Charge Controllers and MPPT Disconnect RS.

Those are 300V AC Midnight Solar SPDs. One is for the Generator input, the one is for the AC Grid Input, and there's a third SPD (non-Midnight Solar, internal to PDP) on the output side.

I have way more SPDs than is probably sensible, as each of the two sub-panels also has them bus-mounted, but they are cheap insurance. The 600VDC house-side PV SPDs are hanging off the bottom of the Disconnect RS and I have another pair out at the array combiner itself.

I posted a system schematic package a while back, but I'll attach it here again. It's no longer 100% correct. Between the time I drew these and the time I got to ordering I had to make some adjustments. -- I'm doing 31 panels instead of 28 and thus the string configuration is a bit different.

Got the combiner installed today and the 140ft of 10gauge THHN pulled and terminated.

Have a "trench inspection" scheduled for tomorrow... here's to hoping I have the grounding and everything else up to code.

If inspection passes I hope to be able to do final concrete on Thursday and install panels on Friday... will post some photos of the trenching later.

w.r.t. the AC2 problem... I haven't messed with AC2 at all yet. I wired up the generator plug but I haven't commissioned it yet. Any tips there to watch out for?

The AGS is a longer-term project as I have a simple pull-start/key-start generator so it would take some clever hacking to get it to auto-start. I more want it in case I need to charge the batteries during a long-term outage w/ no sun. I also am thinking about a military surplus diesel generator upgrade... some day... the house has propane tanks, so right now I have a dual-fuel 12 kw (yeah, right) gas/propane unit which is more than I theoretically need.

I don't have a charge-verter, but I thought about getting one, just in case I need to do a true "black start" as the poco folks call it.

 

[jzampieron]

After a big few days of work... the array is finally finished.

Haven't provisioned the charge controllers or electronics yet. Doing some final metering and such tonight and then "throwing the switch".

Had a single panel cracked in transit so ended up with 30 panels (instead of 31) in 10s2p and 10s1p strings. 3 strings of 10 at the combiner box.

Everything is metering at 3V per CC at the combiner, which is perfect for the Tigos when in shutdown mode.
0.6V per TS4, 5 per string, 2 panels per optimizer.

Lessons learned:
- Iron Ridge Wire Clips are garbage.
- Iron Ridge really needs to mold center marks into their brackets and top caps.
- Scaffolding is basically 100% necessary for an array of any size.
- Midnight Solar stuff is pretty darn great.

Photos attached... dogs for rough scale.

 

[GRMRC]

Thoughts on the electronics install for my 31 panel Aptos 370W system. This is meant to be a grid-sell net-metered w/ battery & generator backup.

Dual MPPT 100-600 w/ RS and Dual XW Pros.

Strings will be 10s2p and 11s1p.

AC Panel on the Right is a grid-tied sub-panel and AC panel on the left is a critical load panel.

Rack in the front is an EG4 6x 5kWh Lifepower4 Rack (30kWh).

The mounting is 1/2" cement board over 3/4" plywood which is painted w/ Intumescent Paint. Looks good and makes it much more fire resistant.

Need to go out and grade the field for the Iron Ridge racking and get the panels set... will post photos on that when finished.

Note: Panels are not connected yet. Hence the wires hanging out of the Disconnect RS. Running grid-tied backup while I finish the excavation.

100% of the install done by me & my wife.
View attachment 224102

Looks nice. I have similar setup. 12.96kWp spread across 2 ironridge ground mounts. 8s2p, 180 & 230 degrees. Many people have challenges with enhanced grid support excessively cycling the batteries with grid sell. I do not have that problem. Less than 10% of the DC energy produced everyday goes through the batteries. My inverters run continuously for 6 hours straight with zero energy coming from the grid. My advice is to use the two XW pros wisely and remember the goal is to produce the most AC power, not the most DC power. I can be more specific if interested.

 

[Shire222]

@jzampieron
You've got a really clean, high quality install. Great work! I have a single XW Pro that I plan to eventually add another to the mix. I'm curious why you decided to go with the Chargeverter instead of leveraging onboard chargers on the XW Pro. You've got 280 amps of charging potential there.

 

[jzampieron]

@jzampieron
You've got a really clean, high quality install. Great work! I have a single XW Pro that I plan to eventually add another to the mix. I'm curious why you decided to go with the Chargeverter instead of leveraging onboard chargers on the XW Pro. You've got 280 amps of charging potential there.

tl;dr: b/c my generator is a semi-cheap-ass piece of trash, but it works... the power output is just ugly and saggy. The 12kW marking on the side is some kind of cruel joke... aka Marketing.

PSA: Avoid the cheaper DuraMax dual and tri-fuel generators. The power quality is horrible even after tuning the engine. Spend the extra on an inverter unit.

Long answer:

Some details were hashed out in another thread about how the XW inverter/charger works internally... but to summarize...

The way I have the XW Pro and MPPTs configured is basically:
1. Charge batteries with solar until full.
2. Then sell power back. (pending new meter)

So I have a "zero-sell", "self-supporting" setup right now. Meaning that the XW Pros won't switch to AC Bypass on the Grid until the batteries are below some percent (20%? 50%?) something like that and then will (in the no-sun case) charge off the grid up to 80%.

Its important to understand that in AC Bypass mode... the Grid is carrying TWO loads: The Output Load ("house") and the Charge Load. My Grid input has no issue doing this (obviously).

The Chargeveter is for the corner case: No Sun, No Grid, Low Batteries.

And I can then use the Chargeverter w/ my PoC generator to fill up the batteries.

I do have a generator plug wired into AC2 on the XW Pro that I tried to use, ... the XW Pro will qualify the input, but as soon as the inverters put a charge load on the generator it trips-off b/c the generator sags a bit.

The key thing to understand is that the XW Pro needs the Generator to be able to carry the SUM of two loads when charging off AC2: The load of the "house" and the "charger" load. My 12kW generator was misbehaving with a 1kW load on it... at least according to the XW Pros.

I'd like to try a better, higher quality inverter generator, but frankly that would have been like $2500 to $3k vs a $500 Chargeverter to do essentially the same thing.

PLUS: If for some reason I ever need to black-start the system, balance a battery, etc. (i.e. batteries totally dead, no XW Pro able to turn on) -- the Chargeverter can do that.

IHMO having the Chargeveter around is just a good thing all around.

 

[ElectricIslander]

tl;dr: b/c my generator is a semi-cheap-ass piece of trash, but it works... the power output is just ugly and saggy. The 12kW marking on the side is some kind of cruel joke... aka Marketing.

PSA: Avoid the cheaper DuraMax dual and tri-fuel generators. The power quality is horrible even after tuning the engine. Spend the extra on an inverter unit.

Long answer:

Some details were hashed out in another thread about how the XW inverter/charger works internally... but to summarize...

The way I have the XW Pro and MPPTs configured is basically:
1. Charge batteries with solar until full.
2. Then sell power back. (pending new meter)

So I have a "zero-sell", "self-supporting" setup right now. Meaning that the XW Pros won't switch to AC Bypass on the Grid until the batteries are below some percent (20%? 50%?) something like that and then will (in the no-sun case) charge off the grid up to 80%.

Its important to understand that in AC Bypass mode... the Grid is carrying TWO loads: The Output Load ("house") and the Charge Load. My Grid input has no issue doing this (obviously).

The Chargeveter is for the corner case: No Sun, No Grid, Low Batteries.

And I can then use the Chargeverter w/ my PoC generator to fill up the batteries.

I do have a generator plug wired into AC2 on the XW Pro that I tried to use, ... the XW Pro will qualify the input, but as soon as the inverters put a charge load on the generator it trips-off b/c the generator sags a bit.

The key thing to understand is that the XW Pro needs the Generator to be able to carry the SUM of two loads when charging off AC2: The load of the "house" and the "charger" load. My 12kW generator was misbehaving with a 1kW load on it... at least according to the XW Pros.

I'd like to try a better, higher quality inverter generator, but frankly that would have been like $2500 to $3k vs a $500 Chargeverter to do essentially the same thing.

PLUS: If for some reason I ever need to black-start the system, balance a battery, etc. (i.e. batteries totally dead, no XW Pro able to turn on) -- the Chargeverter can do that.

IHMO having the Chargeveter around is just a good thing all around.

You should be able to turn down the maximum generator amps pulled by the XW charger supplied to the battery to reduce the sag.

I can run our modest house loads and XW charger on AC2 from my little Honda 3000 W inverter generator (2800 W continuous) via our Victron 120V to 120V/240V split phase autotransformer quite easily if I turn the max battery charge amps down to 28 A x 50 V = 1400 W. This gives the genset some headroom.

I haven't yet investigated in depth, but doesn't the excess power demand from any load applied while charging just either reduce charge rate, or pull power out of the battery?

 

[jzampieron]

You should be able to turn down the maximum generator amps pulled by the XW charger supplied to the battery to reduce the sag.

I can run our modest house loads and XW charger on AC2 from my little Honda 3000 W inverter generator (2800 W continuous) via our Victron 120V to 120V/240V split phase autotransformer quite easily if I turn the max battery charge amps down to 28 A x 50 V = 1400 W. This gives the genset some headroom.

I haven't yet investigated in depth, but doesn't the excess power demand from any load applied while charging just either reduce charge rate, or pull power out of the battery?

I tried that. I turned the charge max down to 500W and had a sub-500W load... so 1kW load on the generator that claims to be 12kW peak or 8kW continuous... as soon as the charger tried to kick on the XW Pro would dis-qualify the AC.

I think the keys in your statement are: "Honda Inverter Generator". I'm going to guess that the power coming out of that is pristine compared to what I'm getting.

Either my Generator is really a PoC or the XW Pro is really sensitive or both. I played with a bunch of voltage and frequency margins in the AC2 settings.

I stopped short of dragging the oscilloscope outside to see what the waveforms looked like when it sagged.

I need something that will just work reliably and the Chargeverter is a heck a lot more forgiving than the XW Pro. Plus I get the extra little things like black-start and battery balance if I run into problems. So overall it was short money for me to get a good system solution.

 

[ElectricIslander]

Chargeverter sounds like a good idea then

 

[JBertok]

Okay, so the XW is ramping up load faster than the generator governor can compensate. The loss of AC2-qualification would be from the drop in frequency, which is dependent entirely on RPM. The generator controller has to do two things in balance - continuously make adjustments to throttle to maintain a constant RPM no matter what the load is, and continuously adjust the stator current to maintain a constant output voltage. The voltage regulation tends to be quick since that's handled by electronics and FETs. The RPM is a mechanical function and will always be slower to respond. One of the reasons Diesels make better generators is just the greater rotating mass to help carry them through rapid changes in load.

Have you tried loosening up the AC2 Low Frequency Disconnect and the AC2 Low Frequency Time Delayed Disconnect in the Advanced Configuration? I think the defaults are 55Hz and 57.5Hz respectively. It would be safe to drop those a little lower buy subtracting the same amount from each. You can also increase the time for the Disconnect Delay to more than 2 seconds. The XW Pro logs will tell you the reason for the disconnect/disqualification, to confirm, and I think it's frequency related from your description of it bogging down. The next step would be to back off the current in Generator Support adjusting Generator Support Amps on AC2. It can be a lot of tedious trial and error getting AC2 to work with small a small generator, as you've found, and most end up charging the batteries externally as you've done.

 

[jzampieron]

I did mess with all the settings for a few hours and then gave up. I need my wife/kids to be able to rely on this and run it and not have to adjust the generator throttle screw frequency if it gets off, etc. The Chargeverter just solves the problem 100%.

I thought about getting a surplus MEP-802 or something like it, but they are still $2500+ used... and again, Chargeverter was sub-$500 or so and I can use with just about any old generator in a pinch. Plug and go.

Agree about the Diesel generators and big rotating mass being preferable.

The generator I have is dual-fuel (gas/propane) and we have large-ish propane capacity at the house already so there's an overall "energy strategy" at play here. Going to have the gas company put a propane hookup near the generator. 300 gal of propane will run a low-load generator a long time if just charging batteries. We also may add a 1k gal propane tank in the future.

Again, the generator is meant to be a backup of a backup, so I don't see a lot of reason to invest more time and/or money into something that's going to maybe get used once in 10 or 20 years. We've been in the house 10+ years and never needed the generator since we bought it 8 years ago. Underground power lines FTW on that. Longest outage has been maybe an hour or two.