Review/Rate my Solar Generator Plan?

[Thersom1948]

I was hoping people might be able to review my solar generator plan for safety and effectiveness.

Please excuse my horrendous drawing.

Do you see anything obviously wrong or unsafe? Any easy ways I could improve? Any additional items I might want to add for more functionality?



Components:

• (6) Santan Solar 250W 60 Cell used panels
• Electrodacus SBMS0
• Growatt SPF 3000 LVM-24P
• (8) 280AH EVE Cells
• Bluesea 7186 80A Breaker
• Bluesea 7189 150A Breaker
• Bluesea 7228 50A AC/DC Breaker
• 100A Shunt
• 300A Shunt
• 1/0 Royal Excelene Welding Wire
• Temco 8AWG PV Wire
• Renogy MC4 Connectors
• Repurposed heavy duty Extension cables for AC Wiring
• Separated CAT5 for SMBS connections

This forum and of course Will's videos were a HUGE help in designing this system.
Thanks!

 

[snoobler]

Why the 100A shunt on the PV in? The growatt will report PV voltage, power and current. NVM... I see it... the Electrodacus.

Typically, shunts go on the (-) terminal, unless Electrodacus says otherwise. Are those shunts or isolators?

A 3S2P panel config may be better if the Growatt as a 130V PV input limit or better (145?). You can go with "standard" 10awg MC4 PV wires with the reduced current and improved voltage drop.

 

[Thersom1948]

Why the 100A shunt on the PV in? The growatt will report PV voltage, power and current. NVM... I see it... the Electrodacus.

Yep - just so the Electrodacus can get all the data it wants. Purely optional, but I figured why not.

Typically, shunts go on the (-) terminal, unless Electrodacus says otherwise. Are those shunts or isolators?

So Electrodacus actually do show it on the positive (+) side on their wiring diagram. Also, Will had his installed on the positive in his "handcart" build that inspired this project.

Educate me: What is the advantage and reasoning for putting it on the negative side?


I think they are just shunts - I was planning to use these:

SMAKN FL-2 300A 75mV Rated Current Voltage Metal Measure Instrument Electronic Splitter - Ground Fault Circuit Interrupters - Amazon.com

SMAKN FL-2 300A 75mV Rated Current Voltage Metal Measure Instrument Electronic Splitter - Ground Fault Circuit Interrupters - Amazon.com

www.amazon.com

Amazon.com: Antrader 100A 75mV Analogue Digital Meter 0-100A Current Shunt Resistors Resistance for DC Current Measure: Automotive

Buy Antrader 100A 75mV Analogue Digital Meter 0-100A Current Shunt Resistors Resistance for DC Current Measure: Ammeters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

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A 3S2P panel config may be better if the Growatt as a 130V PV input limit or better (145?). You can go with "standard" 10awg MC4 PV wires with the reduced current and improved voltage drop.

Growatt does have145V max input.

So 3S2P at Higher voltage will give me less voltage drop and allow me to run smaller wire?

In a previous thread I asked for panel advice and was told that 4S panels or 2S2P would be best both for charging and because shade is a concern and it's going to be easiest for me to put them in a few different places in the yard.

Also - I probably would order the 10awg, but the high quality Temco stuff is out of stock in 10 so I just decided to go with 8, since I can use it for other projects too. I know it's a bit overkill for these runs.

Thanks!

 

[Thersom1948]

@snoobler - I just realized it was you in that other thread giving me those recommendations.

I partly chose the 2S2P (or 2S3P) and 8AWG based on your recommendations in that thread. ?

 

[snoobler]

Standard shunts need to be at the lowest potential, i.e., on the (-) of the battery terminal. They rely on a voltage measurement across them. Electrodacus works differently, so I'd just do it that way.

Heh... and I even responded in the other thread.

Okay, for shading and multiple positions, 2S3P is a better setup. 50A is a bit much for 10awg, so 8awg is the better choice. Watch the ratings on those parallel connectors. They might not make it to 50A.

 

[Thersom1948]

Standard shunts need to be at the lowest potential, i.e., on the (-) of the battery terminal. They rely on a voltage measurement across them. Electrodacus works differently, so I'd just do it that way.

Got it - thank you

Okay, for shading and multiple positions, 2S3P is a better setup. 50A is a bit much for 10awg, so 8awg is the better choice.

Perfect!

Watch the ratings on those parallel connectors. They might not make it to 50A.

So that's a question I meant to ask. I cannot find any MC4 connectors that can handle that kind of amperage.

The Renergy 2>1 connectors claim to be able to support 50A, but it doesn't say if that is Max or Continuous.

If I went with those can I stack them to get the connections I need? Or is that going to introduce too much resistance?

Starting to think it might be easier to give up on the MC4s for the parallel connection and just setup 2 bus-bars for the parallel connection.

Thoughts?

 

[snoobler]

I would assume a rated current is continuous except in the cases of resistors, fuses, shunts, etc.

You could stack them ,but these say 50A:

Amazon.com

 

[Jesswrk88]

I was hoping people might be able to review my solar generator plan for safety and effectiveness.

Please excuse my horrendous drawing.

Do you see anything obviously wrong or unsafe? Any easy ways I could improve? Any additional items I might want to add for more functionality?

View attachment 23428

Components:

• (6) Santan Solar 250W 60 Cell used panels
• Electrodacus SBMS0
• Growatt SPF 3000 LVM-24P
• (8) 280AH EVE Cells
• Bluesea 7186 80A Breaker
• Bluesea 7189 150A Breaker
• Bluesea 7228 50A AC/DC Breaker
• 100A Shunt
• 300A Shunt
• 1/0 Royal Excelene Welding Wire
• Temco 8AWG PV Wire
• Renogy MC4 Connectors
• Repurposed heavy duty Extension cables for AC Wiring
• Separated CAT5 for SMBS connections

This forum and of course Will's videos were a HUGE help in designing this system.
Thanks!

This looks like a great design that I may totally copy! Any changes you made since you set it up? Also, are you able to do remote controlling with the electrodacus and the Growatt?

 

[Thersom1948]

This looks like a great design that I may totally copy! Any changes you made since you set it up? Also, are you able to do remote controlling with the electrodacus and the Growatt?

I haven't gotten it setup yet - Amazon lost some packages and I'm still waiting on a desktop power supply to charge and balance my cells before I start building.

I did not order the Wifi modules for the Electrodacus or the Growatt, but both have one available if you want it for remote management.

 

[Jesswrk88]

I haven't gotten it setup yet - Amazon lost some packages and I'm still waiting on a desktop power supply to charge and balance my cells before I start building.

I did not order the Wifi modules for the Electrodacus or the Growatt, but both have one available if you want it for remote management.

I emailed with Dacian at electrodacus and this was his reply:

“The Growatt can be used as inverter only as that has remote ON/OFF but there is no separate remote for the charger part so if you want to use the grid charger occasionally you can add a Solid State relay on the AC input side that will be controlled by the SBMS0.”

I don’t see a relay like this on your schematic. Do you plan on adding one?

 

[Will Prowse]

Any shunt should work fine with the SBMS, but they can get hot if used with a large continuous load.

I like to size a shunt to 60% of max continuous current.

Ex: I have a 100A shunt, I do not expect to run anything larger than 60A continuously.

Shunts can handle typical surge current with induction/capacitative loads no problem though.

 

[rmsingh]

Wow, I like this setup. I'll probably copy this.

 

[snoobler]

Any shunt should work fine with the SBMS, but they can get hot if used with a large continuous load.

I like to size a shunt to 60% of max continuous current.

Ex: I have a 100A shunt, I do not expect to run anything larger than 60A continuously.

Shunts can handle typical surge current with induction/capacitative loads no problem though.

To Will's bolded statement - routine running at high current above 66-80% rated (depends on manufacturer).

These high temps can actually permanently alter the behavior of the shunt, so they lose their current to mV drop relationship. At rated, the risk is low, but long term running at or hear rated + frequent bursts above rated for things like surge can really do it if they heat significantly.

 

[Thersom1948]

Any shunt should work fine with the SBMS, but they can get hot if used with a large continuous load.

I like to size a shunt to 60% of max continuous current.

Ex: I have a 100A shunt, I do not expect to run anything larger than 60A continuously.

Shunts can handle typical surge current with induction/capacitative loads no problem though.

As far as I know, I have sized my shunts based on that rule.|

PV input: 100A shunt for expected Max typical load of 50A

Battery positive Out: 300A shunt. Even if I was constantly maxing out the Growatt at 3000W AC (which I won't), that would be ~138A DC. That still leaves 40+ Amps of direct DC draw (via Buck Converter which I will also never even get close to) before hitting the 60% rule. And all of those numbers are at or below 0.5C on the battery.

So unless I am missing something, I think all of my components are very conservatively sized?

 

[HaldorEE]

I think 8 of the 280AH cells are a bit much for a handtruck.

This would work fantastic in a little red wagon.

Something like this

Radio Flyer 34" All-Terrain Steel & Wood Wagon

Read reviews and buy Radio Flyer 34" All-Terrain Steel & Wood Wagon at Target. Choose from contactless Same Day Delivery, Drive Up and more.

www.target.com

 

[Thersom1948]

I think 8 of the 280AH cells are a bit much for a handtruck.

This would work fantastic in a little red wagon.

Something like this

Radio Flyer 34" All-Terrain Steel & Wood Wagon

Read reviews and buy Radio Flyer 34" All-Terrain Steel & Wood Wagon at Target. Choose from contactless Same Day Delivery, Drive Up and more.

www.target.com

Agreed - I'm actually building a box for it. The final physical format and layout won't be anything like the handcart build, but that was the video that inspired putting this together - cheap Ali cells plus an All-In-One controller in a semi-portable footprint.

 

[Thersom1948]

Just as an update for anyone copying this build - I had 2 things wrong in my initial diagram.

1. These 6 panels in 2S3P will be 72V, ~25A (not 50A as I originally put)

2. None of the BlueSea Circuit Breakers will work for this application for the PV<>Growatt Connection. They cover plenty of amperage, but max out at 48V DC, so 6 panels in series will be too high voltage for the application.

I ordered a Midnite Solar 150VDC / 60A breaker instead.

 

[Hedges]

If you have 3 strings of PV in parallel (2S3P), it is suggested to have a fuse for each string.
The fuse value would be what is shown on the panel label (probably 15A or 20A).
Fuse holders can be in a combiner box, or are available with MC connectors so they just connect in series with the wires.

The MC fuse holders are not meant to interrupt current, and are not touch-safe (exposed contacts when open.)
So first turn off the breaker you use as PV disconnect, then remove the use holder by disconnecting MC connectors on both ends, then open the fuse holder.

 

[andrewl04]

“The Growatt can be used as inverter only as that has remote ON/OFF but there is no separate remote for the charger part so if you want to use the grid charger occasionally you can add a Solid State relay on the AC input side that will be controlled by the SBMS0.”

I am getting ready to put together a very similar setup. Related question about the Growatt 3000: Do I need a a relay to isolate the DC input from my panels too?
The comment about needing a SSR for the AC input side made me think I might need them on both so the SBMS0 can control all input to the Growatt. For context I am using this is part of a 8 cell Lifepo4 setup in my travel trailer.