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diy solar

Please Help With Direction

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Fearless

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Sep 18, 2023
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Texas
The fragile Texas power grid has me motivated to get started on a DIY solar system. I want to be off-grid or almost off-grid and only use utility power as a fill-in.

Updated 10/31/2023

Today I purchased 2 EG4 18Kpvs and 4 EG4 PowerPro WallMounts from Signature Solar. Nothing could compete with this combo.

I have already purchased 32 Bluesun BSM550M10-72HBD 550 Watt Bifacial https://www.bluesunpv.com/uploadfile/downloads/BSM550M10-72HBD-USA.pdf and show my design for single-axis east-west sun-tracking ground mounts below.

I have 400A service that splits inside the meter box to feed a 150A breaker box by the meter and a 200A breaker box inside the garage. The 200A breaker box has a single 200A breaker box between it and the meter mounted next to the meter.

I have installed a couple of Emporia Smart Home Energy Monitors. After a couple of weeks, my monthly peak 15-minute demand between both panels is 17.57kw. 13.6kw for the 200A panel and 3.97kw for the 150A panel. I added below what I got from the power company.


I would appreciate any guidance to get me on the right track. Thanks!

arraylocation.png
groundmount6.png

6.png
 
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Did you run PVwatts to see if that array will supply your winter and summer loads? Usually there’s plenty of power in the summer for AC.

In the summer how many KWh do you need after peak solar hours (PVwatts can tell you when those are). That gives you some info about how big of a battery you need.

Tracking sounds like so much work to get power, I think it’s mainly a science project to flex and learn

If you’re buying that many batteries, why not buy the UL9540 PowerPro or server rack (which have that certification paired with the 18kpv) instead… you might be sad if you bought $12k of batteries and some random situation requires you to pull a permit. Seems extra weird to forgo UL9540 when the premium in this case is only like 10-20%

That many batteries could well trip over the Residential Code limits wrt how many batteries can be in each class of location. That conditioned space thing is major red flags, I don’t think you can exceed total 40kwh in those areas but I don’t have that page of code in front of me.
 
zanydroid said:
Did you run PVwatts to see if that array will supply your winter and summer loads? Usually there’s plenty of power in the summer for AC.

In the summer how many KWh do you need after peak solar hours (PVwatts can tell you when those are). That gives you some info about how big of a battery you need.

Tracking sounds like so much work to get power, I think it’s mainly a science project to flex and learn

If you’re buying that many batteries, why not buy the UL9540 PowerPro or server rack (which have that certification paired with the 18kpv) instead… you might be sad if you bought $12k of batteries and some random situation requires you to pull a permit. Seems extra weird to forgo UL9540 when the premium in this case is only like 10-20%

That many batteries could well trip over the Residential Code limits wrt how many batteries can be in each class of location. That conditioned space thing is major red flags, I don’t think you can exceed total 40kwh in those areas but I don’t have that page of code in front of me.
Click to expand...
This is the battery rack I looked at https://www.ruixubattery.com/product-page/ruixu-lithium-batteries-kits-15kwh-20kwh-25kwh-30kwh I would need 2 if I go over 30kwh.
 
Yes I’ve heard of this battery. Quick perusal says UL1973 which is not enough for an ESS unless Texas is under older code cycle (NEC and residential code)

Also there is a limit on the maximum per stack kwh / minimum spacing between stacks unless it comes with a UL9540A cert that grants the exception to the standard limit
 
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“Condition Space” I believe just means not too hot nor too cold.

Too cold I believe is below 40F (really 32F), that one is the big issue.
Too hot just causes inverters to derate and extra fast wear on batteries.
Could you put a mini split in the garage? And cover both issues?

Do your best to remain code compliant. (Even if you don’t need the permit).

Good Luck!
 
Rocketman said:
“Condition Space” I believe just means not too hot nor too cold.

Too cold I believe is below 40F (really 32F), that one is the big issue.
Too hot just causes inverters to derate and extra fast wear on batteries.
Could you put a mini split in the garage? And cover both issues?

Do your best to remain code compliant. (Even if you don’t need the permit).

Good Luck!
Click to expand...
This year has seen long strings of days where my garage was over 100 degrees.
 
PowerPro has heaters (I assume Texas isn’t that cold during the days when these would charge), but the environmental range suggests these only help down to 32F.

The main restriction on inverter placement would be close enough to the batteries to meet the installation specs and not cost too much wire/massive conduits. You need massive conductors for 48V.

I am not sure about what code says about whether conduit counts as a penetration for various fire code.
1695522758946.png
 
My meter is on the right side of the house, away from the garage. Do I need to have the system between the meter and the breaker boxes?
 
Do you mean “between” in an electrical wiring sense? It depends.

Yes, if you want the 18kpv to power all house loads without creating a critical loads panel and moving circuits to it. I believe the 18kpv has a 200A internal transfer switch.

No, if you want critical loads or just offset loads when on grid to save bill.

You will need to run 240V with neutral (I think two loops, one to inverter and one back from inverters).

I believe your service equipment (first disconnect and N-G bonding point) is that 200A switch, and your 200 and 150a panels are somehow hanging off it. Could be both directly connected to the output lugs of the 200A switch (is it a breaker? Would be confusing / code violation if not)

This should be covered in the nice wiring diagram in the 18kpv manual.
 
You’re smart to start with the energy monitors to get a good idea about your hourly usage and how much demand is on each of your panels. It looks like your heavier loads are from your 200 amp garage panel, but I can’t tell from the pic what loads are on the 150.

I’m also having trouble visualizing your existing electrical system. The meter, 200A main disconnect, and 150A panel are on the north exterior wall, right? How does the feeder to the 200A panel get there? From the switch? Or as a circuit from the 150 panel? Conductor size for that feeder? Through an attic, or underneath floor, or otherwise?
 
Ideally, you would insert the inverter(s) between the 200A main disconnect and the load centers, to provide whole-home power. Whether that’s feasible depends on how your existing system is configured and how easily you could run large (possibly 4/0) conductor through your house.
 
GuyG said:
You’re smart to start with the energy monitors to get a good idea about your hourly usage and how much demand is on each of your panels. It looks like your heavier loads are from your 200 amp garage panel, but I can’t tell from the pic what loads are on the 150.

I’m also having trouble visualizing your existing electrical system. The meter, 200A main disconnect, and 150A panel are on the north exterior wall, right? How does the feeder to the 200A panel get there? From the switch? Or as a circuit from the 150 panel? Conductor size for that feeder? Through an attic, or underneath floor, or otherwise?
Click to expand...
I'm not sure if the single 200A breaker box is straight from the meter and feeding both breaker boxes or if it is feeding just the breaker box in the garage. I'll check with the electrician. It is feeding through the attic. Yes, the meter is on the north exterior wall. Here are larger images of the breaker boxes.panels.png
 
Yes. If someone can remove the dead front on the disconnect and the 150 panel, you could see how the 200A panel is fed, and also the wire size feeding everything.

Is the south side of the house the only place for your arrays? How do you plan to get the PV wiring from them to the inverters? Through the house or by trenching around it? Keep in mind that any high voltage PV will need to be in metal conduit once it enters the house.

Edit to add: There doesn’t appear to be any breaker tying the two panels together, which means that the 200A garage panel is fed either from a tap off the 200A main disconnect, or possibly from a feed-through lug on the 150 panel. Either way, it would be good to know the conductor size feeding the garage, and what peak loads that panel supplies.
 
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