Off Grid System Design - Issues/Suggestions?

[iamrich]

I have no idea what the Growatt sells for up here.
But as a general comment on prices, it's more complicated than simply converting our currency.
The population and market is only 10% so we don't have economies of scale. Also we have higher social welfare and hence taxes.
And sometimes it seems we're just plain getting ripped off! (But that's a different rant, LOL. Like our cell and internet providers!)

No worries... I am literally your average oblivious American. Not proud of it, but it is what is

 

[Steve_S]

I found a growatt SPF 3000 for $1250 CAD cash and 310w Canadian Solar panels (CS6X 310P) for $175 CAD cash. Planning on 4 panels, the growatt and 100AH lifepo4 or 200AH FLA. Sound good?

A question on the growatt - I dont see that it includes a battery temperature sensor... is this a problem?

The TEMP Sensor is typically used to calculate when temp Compensation has to happen for Flooded Lead Acid batteries. LFP does not use Temp Compensation during charging. With "some" inverter systems, that can also be used as an ON/OFF signal from a Relay, I am not sure IF Growatt allows for that use. Even if it did, that would require a Smart BMS with Relay Control.

 

[SolarDR]

Do NOT buy 12V solar panels. They are waste of money. I can buy 1000W of grid-tie panels cheaper than you can buy 3 100W panels.

I would also recommend skipping 12V and go straight to 24V. The controller will be happier with lower amperage.

Your consumption numbers do not look realistic. A freezer that consumes only 250W per day? I would double your expectations and plan on making 3kWh per day. With 1000W of panels, 3kWh per day is very doable.

I can't recommend Renogy to anyone anymore. Look at Epever's 50A MPPT. That has a far higher Voc maximum. Or, buy a quality controller, like a MorningStar, Midnight, or Outback.

I could put together a 1000W system cheaper than your 300W system.

This is Bang on, don't go 12V go 24V this gives you room to go if you need more batteries since you really want to stick to 2 or 3 banks Max. Also you can double your panels without going to an additional charge controller.

 

[SolarDR]

The TEMP Sensor is typically used to calculate when temp Compensation has to happen for Flooded Lead Acid batteries. LFP does not use Temp Compensation during charging. With "some" inverter systems, that can also be used as an ON/OFF signal from a Relay, I am not sure IF Growatt allows for that use. Even if it did, that would require a Smart BMS with Relay Control.

With both Rolls and Crown your battery warranty is void without a Temp sensor, while you could get away without one on the Inverter/charger the Solar MPPT must have one!

 

[jordanregier]

Do you know if you can use a temperature sensor with the growatt MPPT without doing custom work?

Another question... My 3 way RV fridge is currently run off propane but requires 12v to operate. I also have a 12V water pump. After reading multiple threads I see I have a few options:
1) Use a 24V to 12V converter (The battery bank will be around 50 feet from the 12V appliances... may be an issue with voltage drop? Also requires a 50' run of cable)
2) Use a 120VAC to 12VDC power supply
3) Swap the pump for a 120V pump. I have a 12V 70AH AGM battery for the fridge now, I could hook up a standard 12V battery charger plugged into the wall to keep it topped up. I am unsure how many watts the fridge uses but I would think it is very minimal.

What would you recommend?

 

[SolarDR]

Do you know if you can use a temperature sensor with the growatt MPPT without doing custom work?

Another question... My 3 way RV fridge is currently run off propane but requires 12v to operate. I also have a 12V water pump. After reading multiple threads I see I have a few options:
1) Use a 24V to 12V converter (The battery bank will be around 50 feet from the 12V appliances... may be an issue with voltage drop? Also requires a 50' run of cable)
2) Use a 120VAC to 12VDC power supply
3) Swap the pump for a 120V pump. I have a 12V 70AH AGM battery for the fridge now, I could hook up a standard 12V battery charger plugged into the wall to keep it topped up. I am unsure how many watts the fridge uses but I would think it is very minimal.

What would you recommend?

I don't know for sure I really like the look of the Goat but from all the digging I have done it does not look like there is any Temperature control on it, like almost all the other all in one units, so a great one for Lithium, but not any good for AGM or other Lead Acid.

I do a great number of off grid systems I always do 24V or 48V you will not be happy with 12V I made the mistake early on in my Solar projects, great for an RV but that's it.

As far as 12V get a 120VAC to 12VDC. You can find many out there, for the fridge it's so little current a very small 12V adapter works fine. (Used this many times for that application). The pump is more power but again find out how many amps you need one usually about double the required amps. Another good solution is an RV Converter board the high quality ones have a very small standby current and you can run all 12V loads of it.

The biggest thing I recommend with none lithium batteries is a very good SOC meter one with a shunt, You really need to ensure you never go below 50% SOC, with AGM I try to use only 40% of the battery capacity.

Good Luck!

 

[Steve_S]

We recently purchased a cabin in the Parry Sound area (Ontario, Canada) and are looking to go solar and mitigate the need to run our generator (5500w yamaha). The cabin is typically used 3-4 days once per month and for a week twice a year.

Key Requirements:
1) System that can often power our requirements (1500Wh/day) - I am okay running the generator if we have multiple days of no sun
2) Budget - $3000 CAD
3) Expandable if we find the cabin is used more often or we require more solar power

The #1 post by the op.

This has gotten somewhat off track.
It can get cold up here and -30C isn't unusual in winter, even colder on occasion. Therefore this has to be a consideration for batteries.
There are several options, like the AIO's, component systems, and even more and this is where it all get's muddled. KISS applied is always best.

Now, this is a Cabin, used part-time for now. Later it may be used more often and for longer (probably will once you really get into it). If you feel that it will be something that you will use more & grow with, then planning a setup that will let you grow it over time is important because it will save you time & money. That helps marriages stay happier right! But if you want a more "Quick & Simple" answer something like what I link below may be the solution. Then you can leave panels up on the roof or rack or whatever and just disconnect & go.

Now here is one KISS option to ponder,
but would you be willing to drag the unit back & forth ?

There is another factor to consider as well, I'm not sure how remote your place is, I'm in a pretty sparsely populated area but there are still a fair bit of break-ins on cabins, hunt camps, cottages etc. So the security of your gear has to be pondered as well, it sucks but it is a factor.

 

[jordanregier]

Thanks for the replies guys!

The cabin is about 6kms into the bush by ATV so hauling something like that in and out isn't feasible. Looks like a slick unit tho!

So... the growatt doesn't have the temperature sensor capability... what now? Live with it / modify the charging parameters on the safe side? Rethink the growatt recommendation and look for a different brand inverter/charger?

 

[jordanregier]

I suppose the other option is to go with LiFePo4 batteries as they do not need the temperature sensor? I started a thread to get feedback on these cheap batteries I found locally but haven't received a response. https://diysolarforum.com/threads/tournament-lithium-500cad-12v-100ah-lifepo4.21632/

 

[jordanregier]

Okay guys I am getting ready to order the balance of my system and I am hoping someone can help me out with a few questions before I order. My system as of right now is:
- 24V 205AH bank (4x6V FLA batteries)
- SPF 3000 growatt
- 2S2P Solar Array, 390W each panel

1) Cables and Breakers - I am getting conflicting information as to what size to use... the manual lists 2awg and no breaker size:

However the altestore calculator lists 4/0 and a 250amp breaker.


Is it okay to go with 2/0 and 200amp breaker (shown below). I wont be powering any heavy loads so I dont forsee me tripping the breaker. I cant find tinned copper lugs on amazon for 2/0 only bare copper... is that an issue? Can I use the 2/0 cables between the batteries?



My solar supplier told me to put a 20amp breaker between the solar array and the growatt. I have read a few posts saying they are not required. What do you guys think?

2) Grounding / Bonding

I currently have a small breaker panel in the cabin that is powered by the generator, it is not grounded. Should I be installing a grounding rod tied to the breaker panel or should it be tied to the growatt or do I need multiple? Any pointers/diagrams on grounding/bonding this system would be much appreciated. Bonding occurs in the cabin breaker panel correct? Would this grounding rod work?

 

[HRTKD]

Cable size depends on the expected amps and the length. If the Alte calculator allowed you to enter the length (roundtrip) and that's what you came up with then go with the 3000 watt line since you have a 3000 watt inverter. Seems a bit large to be for wire, but larger is better except for the cost.

For the circuit breaker between PV and MPPT I used a double pole breaker on a DIN rail. Size yours based on amps coming in from the PV.

2P 250V Low-voltage DC Miniature Circuit Breaker For Solar Panels Grid System Din Rail Mount 16A - - Amazon.com

2P 250V Low-voltage DC Miniature Circuit Breaker For Solar Panels Grid System Din Rail Mount 16A - - Amazon.com

www.amazon.com

The breaker you posted looks like an off-brand knockoff. Cooper Bussman or Blue Sea (which is the Cooper Bussman I believe) is the safe/recommended way to go.

 

[Hedges]

You plan for FLA battery. If you'd like to spend more money, perform less maintenance, have better freeze protection, consider AGM.
(The best quality FLA could outlast AGM if treated right.)

If you do use FLA, put in a separate compartment from electronics due to corrosive fumes.

There should be a temperature sensor on battery for charge controller.

Yes, 200A OCP is OK for 2/0. Besides breakers, another option is fuse + switch.

Typically at least one ground rod, wired to main breaker panel. Neutral ties to ground at the panel (green screw through neutral bar into box.)
That rod at 4' is too short for US code. We use an 8' 1/2" or 5/8" copper-plated steel rod. Sometimes other methods. We tie to metal pipes as well.

 

[jordanregier]

Thanks for the replies. Hedges - The growatt does not have a temperature sensor, is this a major issue? I posted about this above (post #28).

 

[iamrich]

1) Cables and Breakers - I am getting conflicting information as to what size to use... the manual lists 2awg and no breaker size:

However the altestore calculator lists 4/0 and a 250amp breaker.

If my fuzzy math is correct you will have 65a of PV going to the batteries (1560w/24v) and a max of 125a going from the batteries to the inverter (3000w/24v). IMO 2awg is fine (and is what I am using). I would fuse with a 150a breaker. Just get ready made cables like these:

https://www.amazon.com/dp/B00SFXVMYW?psc=1&ref=ppx_yo2_dt_b_product_details

Just get two pieces of red (Growatt to fuse to battery) and one piece black (battery to Growatt).

Is it okay to go with 2/0 and 200amp breaker (shown below). I wont be powering any heavy loads so I don't foresee me tripping the breaker. I cant find tinned copper lugs on amazon for 2/0 only bare copper... is that an issue? Can I use the 2/0 cables between the batteries?

I used this one:

Amazon.com: WindyNation ANL Fuse Holder + ANL Fuse (2pcs 150A Fuse): Automotive

Buy WindyNation ANL Fuse Holder + ANL Fuse (2pcs 150A Fuse): Vehicle Audio & Video Installation - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

My solar supplier told me to put a 20amp breaker between the solar array and the growatt. I have read a few posts saying they are not required. What do you guys think?

You can use inline fuses, or a combiner box. I used the Midnight Solar box and breakers, but that adds $150+ to the deal. I don't think you must have them, but it's nice to have breakers so you can turn off each PV string. This allows you to see how much Volt/Amp/Watt each string is producing and let's you turn it off if you have to do maintenance.

2) Grounding / Bonding

I currently have a small breaker panel in the cabin that is powered by the generator, it is not grounded. Should I be installing a grounding rod tied to the breaker panel or should it be tied to the growatt or do I need multiple? Any pointers/diagrams on grounding/bonding this system would be much appreciated. Bonding occurs in the cabin breaker panel correct? Would this grounding rod work?
View attachment 46750

My garage is stand alone so I bonded ground to neutral in the main panel. I have the ground going from the grounding rod to the main panel (six breaker Square D box) to the combiner box to the panels on the roof. The LV2424 is grounded to the main panel as well.

I used an 8 foot 5/16" rod on my setup. Got it at Home Depot for $13

ERICO 5/8 in. x 8 ft. Copper Grounding Bar Rod 615880UPC - The Home Depot

ERICO copper-bonded ground rods are the highest quality ground rods available today. We use a unique manufacturing process, which includes drawing the steel rod to size before the copper bonding process

www.homedepot.com

 

[Hedges]

So... the growatt doesn't have the temperature sensor capability... what now? Live with it / modify the charging parameters on the safe side? Rethink the growatt recommendation and look for a different brand inverter/charger?

Unless ambient temperature remains fairly constant, a temperature sensor is necessary to adjust lead-acid charge voltage - higher when cold, lower when hot. Without that the battery would be under- or over-charged, and for lead-acid that shortens life. Even the mechanical regulators under a car hood provide this. I suppose a manual change to settings for summer/winter would help.

Lithium doesn't mind being left partially charge. Even if cell voltages do vary with temperature, the knees of the curve are apparently distinct enough.

Chart page 42 shows charge voltage varies 0.125V/cell between zero C and 30 degrees C, 0.5V for a 12V battery.

http://sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf

 

[David Hamand]

Thanks for the responses!

Panels - Sounds like I need to up my panel array, shoot for 1000W and add if necessary. I will look at those suppliers in the US.
MPPT - Do you guys think it's worth the extra $$ to get a victron controller? Bluetooth and not needing a separate controller in the cabin would be nice. Victron or Epever... I will go with 50amp.
Inverter - Other than the growatt and LV2424, recommendations for around the $1000 inverter/chargers for this system?
Batteries - How many total AH @ 24v would you recommend?

Check out the solar shopping mall in Mississauga/Oakville. I bought "B" grade panels from them last year, no issues. They have 280w for $160. They usually have used panels cheap too!

 

[jordanregier]

I recently purchased the Growatt SPF 3000TL LVM-24P and I am getting ready to install it. I am hung up on the neutral/ground bonding with my all-in-one Growatt as the manual does not explicitly say how the N-G bond operates. My setup will be:

1) Growatt - AC out feeding a small sub-panel with 4-15amp circuits throughout the cabin. The sub-panel does not currently have a N-G bond.
2) A generator with an N-G bond will be used if the batteries are running low. I believe the growatt will charge the batteries and simultaneously power the cabin?

What I do not know is how the growatt handles the N-G bond and where I should install the N-G jumper (if needed at all).

Any feedback would be greatly appreciated. Thank you.

 

[12VoltInstalls]

I always find it interesting when I read system advice threads and then the advice assumes the op needs ‘ideal’ everything. As above several things stated that “won’t work” and that 12V is insufficient.

But I don’t know that small systems at 12V are insufficient.
Granted I do it full time 8 months of the year, not occasional. Nevertheless, I’ve been running on a 12V minimalist system myself for three years. Do I need more? Yes, I guess. But I don’t have a generator and haven’t needed one. Laptop, tablet, phones, water pump, vacuum, lights, exhaust fan... All fine.

just buy a bigger charge controller than you “need” - it will never be stressed and if you need or want more panels someday? No big purchase to upgrade capacity of the controller.

The perfect system is one that meets the goals and budget of the user.

 

[45North]

I always find it interesting when I read system advice threads and then the advice assumes the op needs ‘ideal’ everything. As above several things stated that “won’t work” and that 12V is insufficient.
But I don’t know that small systems at 12V are insufficient.

I've noticed that too.
I call it the "Mine is bigger than yours" syndrome.

 

[iSwannie]

I recently purchased the Growatt SPF 3000TL LVM-24P and I am getting ready to install it. I am hung up on the neutral/ground bonding with my all-in-one Growatt as the manual does not explicitly say how the N-G bond operates. My setup will be:

1) Growatt - AC out feeding a small sub-panel with 4-15amp circuits throughout the cabin. The sub-panel does not currently have a N-G bond.
2) A generator with an N-G bond will be used if the batteries are running low. I believe the growatt will charge the batteries and simultaneously power the cabin?

What I do not know is how the growatt handles the N-G bond and where I should install the N-G jumper (if needed at all).

Any feedback would be greatly appreciated. Thank you.

The Growatt has a setting #24 that determines this. Default is disabled meaning neutral and ground are disconnected. Hope this helps.