Upgrading old system help

Jaya · Apr 17, 2023

Inherited an old 12V lead acid system and ended up changing the batteries/inverter/solar panel controller. Still 12V, but now with four 206ah SOK LiFePO4 wired in parallel to a DC fuse box for the lighting, water heater and water pump; a victron mppt; and a 3000w inverter (pure sine wave) for the additional AC load.

I have two questions:
1) I have the copper ground from the old battery bank attached to the new bank, but the solar panels are grounded and am wondering if that is too many grounds?
2) Will 4/0 be overkill for recabling the DC house fuse to battery bank, the inverter to bank and the controller to bank? All the cables will be 5ft or under in length. The current cables are degrading/old and too long. I have 2awg within the battery bank.

Rednecktek · Apr 17, 2023

Jaya said:
1) I have the copper ground from the old battery bank attached to the new bank, but the solar panels are grounded and am wondering if that is too many grounds?

Are the solar panels grounded to their own rod or is there a wire running all the way back to the main breaker box?

Jaya said:
2) Will 4/0 be overkill for recabling the DC house fuse to battery bank, the inverter to bank and the controller to bank? All the cables will be 5ft or under in length. The current cables are degrading/old and too long. I have 2awg within the battery bank.

What's the maximum draw of all the equipment added up? 2/0 is plenty up to 200a which is all any individual battery can do so I would say that 4/0 is not excessive overkill. 2AWG was only good up to about 120a so sizing up now is probably a good idea.

Jaya · Apr 19, 2023

Rednecktek said:
Are the solar panels grounded to their own rod or is there a wire running all the way back to the main breaker box?

What's the maximum draw of all the equipment added up? 2/0 is plenty up to 200a which is all any individual battery can do so I would say that 4/0 is not excessive overkill. 2AWG was only good up to about 120a so sizing up now is probably a good idea.

Thank you for your reply. The solar panels are grounded to their own rod.

I've no idea the max draw. I am working on upgrading the system that came with the house as I live remotely and supplies/services are not readily available, so I upgraded the batteries based on what had been there. On the AC side, the inverter is mainly used as a charger for laptops, phones, vacuum, tools and the only long draw is an air purifier during fire season. The DC side is lights, hot water heater, RV water pump, a couple of fans and the long draw would be another external water pump when I need to transfer water.

Jaya · Apr 19, 2023

Rednecktek said:
Are the solar panels grounded to their own rod or is there a wire running all the way back to the main breaker box?

What's the maximum draw of all the equipment added up? 2/0 is plenty up to 200a which is all any individual battery can do so I would say that 4/0 is not excessive overkill. 2AWG was only good up to about 120a so sizing up now is probably a good idea.

Oh and if I'm upgrading the wire to the DC fuse box, there's a T class fuse (110a) which I'm guessing I'll be switching out as well to 250a (195x1.25)?

Rednecktek · Apr 19, 2023

Jaya said:
Oh and if I'm upgrading the wire to the DC fuse box, there's a T class fuse (110a) which I'm guessing I'll be switching out as well to 250a (195x1.25)?

Yes. In a perfect world you'd have 2 fuses, 1 for each 24v bank of batteries but your math is correct.

50ShadesOfDirt · Apr 19, 2023

If you identify the solar panels, via their label on the back of one, you can then dig up online the installation guide for it. This might tell you how the panel (frames) should be grounded. My guess is that the panel frames are separately grounded for lightning protection.

Everywhere else, there should be only one ground (multiple bonded points to one ground are the same as one ground), and this is usually at or near the AC breaker panel.

As (I believe) you have a mixed system, and how that was wired may not have been discovered yet, I'd still follow the rule of "one ground" for the house wiring, such as it is. The sooner you discover/review all the wiring, the better ... who knows what other fun things are in there. If you do find multiple ground rods or such, then that can be puzzled out, depending on how the wiring got done.

A local electrician would know the rules of NEC code (or whatever applies) and your area, and would be able to review the grounding setup you've got, and test it's effectiveness. Because you are remote, you may have to do the legwork yourself, draw it up a bit, and run it past someone, who may not otherwise come out to where you are. I think it's very worthwhile to have a diagram of what you've got anyway ...

Adding this section to differentiate: "System Grounding vs. Equipment Grounding"
- System grounding is the intentional connection of a current carrying conductor to earth ground. In U.S. homes, the neutral conductor bonds to ground in one location (typically in the main service panel). On PV systems, traditionally, the DC negative bonds to ground but is often done internally to the equipment and isn’t always a direct connection (thus, identify what components you have, get the install guides).
- Equipment grounding bonds all non-current-carrying metal parts to ground. In a PV system, this includes racking, solar panel frames and equipment enclosures.

Hope this helps ...

Jaya · Apr 19, 2023

50ShadesOfDirt said:
If you identify the solar panels, via their label on the back of one, you can then dig up online the installation guide for it. This might tell you how the panel (frames) should be grounded. My guess is that the panel frames are separately grounded for lightning protection.

Everywhere else, there should be only one ground (multiple bonded points to one ground are the same as one ground), and this is usually at or near the AC breaker panel.

As (I believe) you have a mixed system, and how that was wired may not have been discovered yet, I'd still follow the rule of "one ground" for the house wiring, such as it is. The sooner you discover/review all the wiring, the better ... who knows what other fun things are in there. If you do find multiple ground rods or such, then that can be puzzled out, depending on how the wiring got done.

A local electrician would know the rules of NEC code (or whatever applies) and your area, and would be able to review the grounding setup you've got, and test it's effectiveness. Because you are remote, you may have to do the legwork yourself, draw it up a bit, and run it past someone, who may not otherwise come out to where you are. I think it's very worthwhile to have a diagram of what you've got anyway ...

Adding this section to differentiate: "System Grounding vs. Equipment Grounding"
- System grounding is the intentional connection of a current carrying conductor to earth ground. In U.S. homes, the neutral conductor bonds to ground in one location (typically in the main service panel). On PV systems, traditionally, the DC negative bonds to ground but is often done internally to the equipment and isn’t always a direct connection (thus, identify what components you have, get the install guides).
- Equipment grounding bonds all non-current-carrying metal parts to ground. In a PV system, this includes racking, solar panel frames and equipment enclosures.

Hope this helps ...

It does. Thank you.

Jaya · Apr 20, 2023

Rednecktek said:
Yes. In a perfect world you'd have 2 fuses, 1 for each 24v bank of batteries but your math is correct.

The old T fuse is a JLLN (littlefuse) and a bit pricey at 250a. Do you by chance know if they are interchangeable with other brands?

Hedges · Apr 20, 2023

Any name-brand class-T 300V (not 600V) fuse should be similar.

I'm seeing > $100 from some sources, more in the $40 to $60 range elsewhere.
Blue Sea rebrands one of the top names, probably Littlefuse.

https://www.digikey.com/en/products/detail/riedon/JLLN-250/8601751

https://www.automationdirect.com/adc/shopping/catalog/circuit_protection_-z-_fuses_-z-_disconnects/fuses/current_limiting_class_t_fuses/tjn250?utm_term=&utm_adgroup=Circuit%20Protection

Jaya · Apr 20, 2023

Hedges said:
Any name-brand class-T 300V (not 600V) fuse should be similar.

I'm seeing > $100 from some sources, more in the $40 to $60 range elsewhere.
Blue Sea rebrands one of the top names, probably Littlefuse.

https://www.digikey.com/en/products/detail/riedon/JLLN-250/8601751

https://www.automationdirect.com/adc/shopping/catalog/circuit_protection_-z-_fuses_-z-_disconnects/fuses/current_limiting_class_t_fuses/tjn250?utm_term=&utm_adgroup=Circuit%20Protection

Class T Fuse - 250 Amp - Blue Sea Systems

Use with Class T Fuse Blocks for circuit protection of devices including inverters. high interrupt capacity for large battery banks including Lithium-ion and TPPL batteries.

www.bluesea.com

JLLN-250, 250A Class T Fuse | DonRowe.com

The TF250 offers 250 amps of over-current protection and works as a replacement or spare fuse for Class T fuse kits.

www.donrowe.com

250A Class T Fuse | West Marine

Check out our 250A Class T Fuse and more from West Marine!

www.westmarine.com

Thank you!

Upgrading old system help

Jaya

New Member

Rednecktek

Solar Wizard

Jaya

New Member

Jaya

New Member

Rednecktek

Solar Wizard

50ShadesOfDirt

Solar Enthusiast

Jaya

New Member

Jaya

New Member

Hedges

I See Electromagnetic Fields!

Class T Fuse - 250 Amp - Blue Sea Systems

JLLN-250, 250A Class T Fuse | DonRowe.com

250A Class T Fuse | West Marine

Jaya

New Member

Class T Fuse - 250 Amp - Blue Sea Systems

JLLN-250, 250A Class T Fuse | DonRowe.com

250A Class T Fuse | West Marine

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