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diy solar

Update: 35KW ground mount system added to existing 3kW rooftop solar in Phoenix, AZ.

side comment
Trenching under a short section of sidewalk is easy (even for DIY) with the right tools.... though short runs are easier..
of the truly low-tech approach ... I've done the trenching nozzle on the end of garden hose.. worked great... easy to McGuyver a pole to keep hose straight and level...

I've seen later threads about running along wall, which was my first thought...
but *if* you come back to this... instead of the blue line (single larger trench) , I'd argue for 2 separate trenches (1st heading due north under narrow sidewalk, then crossing under sidewalk (door) to get to basement access area where your blue line is) being much easier
So something like this?

1722969227612.png
 
There are those that get 'religious' over that particular debate. Personally, I suspect the truth is closer to 'it depends'
Shade considerations typically drive discussion of power optimizers or micro-inverters, which don't really apply in your situation.
There are times when the cost of micro-inverters (or power optimizers) is not cost-justified. I've heard others comment that as panel count goes up, the harder it is to justify micro-inverters (with a rough rule-of-thumb in the 10kW system size, but I have no idea how accurate that might be).

If you go to r/enphase, which has lots of DIYers but (I would hope) very few off-grid DIYers, you'll get flamed for recommending strings. LOL. Actually I have to resist roasting noob wannabe off-grid DIYers that go on that forum talking about complex Enphase installs to work off-grid.

So, adding a few anecdotal and objective data points:
  • Hoymiles microinverters have an open programmatic interface that to me looks VERY utility focused. They also target 500W per panel power levels that, when factoring in overpaneling, correspond better to utility-size panels than residential panels. Little need for that in residential
  • For small patio or < 4 or 5 panel roof segments, microinverters are way better. If we look at European patio solar panels, it's probably 90% microinverters. (Though at that point it gets ontological... is a string inverter serving 800W of panels with <80V start / operating voltage a microinverter or a string inverter).
 
If you go to
yea typical rationalization ('I bought it so it must be the best in all circumstances')/fan boy response... in my mind those kind of responses qualifies as noise instead of signal, which one runs to all over the place. some places have a worse S/N ratio than others

On the other hand, even when I'm a fan of certain vendors/solutions based on experience, my career was always about recommending the right tool for the job (not necessarily the one I was personally most comfortable with), which was always a multi-variant calculation [i did take multi-variable calculus in college, for fun (not required for major) so yea, writing was on the wall, so to speak]
 
yea typical rationalization
There are definitely fanboys there.

But there are also a lot of people there that are very familiar with Enphase and the strengths/weaknesses.

Whereas if anything, here there could be the opposite bias in several ways. For instance, someone who is a microinverter enjoyer or enjoyer of both may not see your post, and only the anti-microinverter partisans see your post. Quite likely on a forum that maybe has 20-25% active members that have a balanced opinion.

Or if you do bad statistics, and do beauty contest (number of posts supporting each architecture) without correcting by the population, geographic, etc bias of the forum. The popularity contest way of evaluating technology has merits in some cases... but not in deciding whether microinverters or string inverters are the superior option in objective terms

It's probably valid in gauging things like market adoption / viability of getting aftermarket support. If you must have local support for your solar, and none of your neighbors have architecture X from brand Y, then X+Y is not the right answer.
 
So something like this?
in terms of where to under sidewalk, yes
*if* pondering this, I add a consideration for long-term maintenance - either
- a curved routing that would enable (at least not outright prevent) pulling/ replacing wire in buried conduit
or
- adding an access box for similar/same in between the 2 sidewalk trenches

I'm sure there are even better ideas... just try avoid in 10-20 years the 'boxed' in situation you have now
 
in terms of where to under sidewalk, yes
*if* pondering this, I add a consideration for long-term maintenance - either
- a curved routing that would enable (at least not outright prevent) pulling/ replacing wire in buried conduit
or
- adding an access box for similar/same in between the 2 sidewalk trenches

I'm sure there are even better ideas... just try avoid in 10-20 years the 'boxed' in situation you have now
Yeah I figured I'd need to do more of a sweeping transition, it was just a rough illustration. When you're talking about an access box, are you saying a buried one, or above ground?
 
Yeah I figured I'd need to do more of a sweeping transition, it was just a rough illustration. When you're talking about an access box, are you saying a buried one, or above ground?
Figured on the rough illustration, just meant as food for thought

I'd defer to others with more knowledge of wiring, long-term maintenance, etc... this is NOT my area expertise
but for discussions sake, I'd probably go in-ground... above ground means wires need to angle up into box, then back down under adjacent sidewalks ... with it just being a large dirt area, in ground seems 'straighter' run (less elevation change) to me... but I may be missing obvious considerations (like avoiding water pooling inside the box).. in part, I'd consider what, if any future plans are for that space (aesthetics, etc)
If wire bend not a problem, then above ground
... nevermind... I can come up with Pro's and Con's for each approach .. and I'm only guessing.
I'll stop before I dig myself a into a hole (if I haven't already)

The issue will be with a curved routing, is there a need for an intermediate access/pull(or at least 'assist') point?
if yes, those who say yes can comment on positioning. If no, then don't bother ??
 
Nothing wrong with micro inverters, I actually plan to have some in my system.
It's just not the norm around here, in this forum.
So I have been running into issues combining my current PV system in with the new system.

I'm now contemplating getting a pair of the Sol-Ark 15k's and just offloading the microinverters. Each can take up to 20kW of input,, so I could retire my current string inverter, run the old AND new panels into the 15k's, simplify install with all of the built in pass through breaker, DC disconnect, battery backup capabilities, expandability, etc.

Is running DC that distance at 400'ish volts DC going to be an issue with that distance?
 
Running distance with PV DC is the best way to go.

Not only is it less loss because higher voltage, voltage drop doesn't cause disconnect (the way AC voltage rise from an inverter can exceed grid spec) or performance issues the way brownout from inverter/generator to a motor does.

You don't even need to limit voltage drop to 3%. If it hits 10% or even 25% at peak PV current, the system just keeps working. Only if it drops to minimum MPPT voltage will it cause additional loss beyond I^2R loss in the wire.
 
So I have been running into issues combining my current PV system in with the new system.

I'm now contemplating getting a pair of the Sol-Ark 15k's and just offloading the microinverters. Each can take up to 20kW of input,, so I could retire my current string inverter, run the old AND new panels into the 15k's, simplify install with all of the built in pass through breaker, DC disconnect, battery backup capabilities, expandability, etc.

Is running DC that distance at 400'ish volts DC going to be an issue with that distance?
It's always recommended to run the longest distance of your system with the highest voltage of your system. (This is usually the PV DC)
 
It's always recommended to run the longest distance of your system with the highest voltage of your system. (This is usually the PV DC)
My engineering/permitting guy sent me a message this morning that I can't do a line side tap on a panel that has loads in it? I'm not sure if we're having a communication breakdown or not. I am waiting for a call back.

Can you tell me if my thoughts on this are correct of my current configuration vs the proposed?


Current configuration:
1723236202050.png


New configuration:
1723235664403.png
 
What you have would work with the following scorched earth/brute force setup (cheaper ones are possible)

200A disconnect is fused
Line side of 200A disconnect scaled up to 400A wire to Panel Basement, 400A wire to PV meter
Panel Basement protected with 200A main breaker
 
That’s a load side tap. It’s on your side of a disconnect from the meter.

Persisting in calling it a line side tap will confuse someone using precise language (like hopefully your permitting person is)
Ok, that makes more sense. So only if it were prior to the disconnect would it be a "line side". I thought load side pertained only to when it was backfeeding a breaker.

I appreciate the clarification.
 
My engineering/permitting guy sent me a message this morning that I can't do a line side tap on a panel that has loads in it? I'm not sure if we're having a communication breakdown or not. I am waiting for a call back.

Can you tell me if my thoughts on this are correct of my current configuration vs the proposed?


Current configuration:
View attachment 235333


New configuration:
View attachment 235329
Both drawings are technically the same thing.
If your utility company requires the second (dedicated PV) meter, you will have to configure it how they want it.
Is your existing system using a separate meter? (I haven't seen one in your pictures)
 
Both drawings are technically the same thing.
If your utility company requires the second (dedicated PV) meter, you will have to configure it how they want it.
Is your existing system using a separate meter? (I haven't seen one in your pictures)
The current system does have a dedicated generation meter, but it's backfeeding into a 25A breaker in the current system

Here's a pic of the current setup:
1723241337288.png
 
i think the bypass of the 200A subpanel’s 120% rule bottleneck, as you have in the second picture, is the way I would go. You can look at the 705.12 section on interconnecting into a feeder.

A special case that would help is to rearrange the order of wires. Disconnect - subpanel - meter, ie feed the PV on opposite side from the utility power. There is a clause in 705.12 for this.

EDIT: you have this already

In some cases opposite side feeding lets you have smaller wire than same side feeding. I haven’t reread 705.12 to see if that’s the case here. The two ordering might be identical.

In general for taps with different OCPD it needs to either be conduit protected and shorter than maximum tap length or all wire sized to maximum OCPD. Permit drafting person should know this
 
You can talk with your engineer and the utility company.
But I think you should be able to move the one production meter connection from the indoor service panel to the spare breaker slot in the outside service panel.
And connect both systems through it.
 
You can talk with your engineer and the utility company.
But I think you should be able to move the one production meter connection from the indoor service panel to the spare breaker slot in the outside service panel.
And connect both systems through it.
This would simplify the tap calculation and avoid having to vampire tap into the feeder or cut it and resplice

It may depend on how the math works out for the busbar in the service panel. If it is rated to 600A (assuming you have 3x disconnects each accepting up to 200A) it is fine.
 
It's definitely big enough to be a 600a. I can't read the labels.
(400a at the minimum)
But the feeder is definitely not 600a , currently.
 
Are there interesting performance or functional differences between the two tie-in points?

- Through existing feeder/feeder
- Through new disconnect/feeder

Offhand:
- the new disconnect allows PV to be shutdown from either the inside or the outside.
- new disconnect allows the subpanel and PV to be shutoff independently.

Existing disconnect, looks like the subpanel has no main breaker, nor space to add one. Is it a convertible panel? I don't think increasing the size of the feeder leading to it is enough to protect the busbar from potential 200A of grid + 125% * 100A of solar -- you would want a 200A main breaker.
 
I would like to see the labeling and existing breaker sizes on the outside main service panel. To determine if what I suggested is the best and simplest solution.
 

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