diy solar

diy solar

Set up advice

tadaf

New Member
Joined
Dec 26, 2020
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12
Hoping to get the correct set up. I have watched a lot of Will Prowse’s video (as well as bought the book) and other youtubers but it’s too advance for my solar brain to understand. I have purchased and would like to install a 24v (2 x 12volt in series) 206AH SOK battery with an all in one Growatt 24V SPF 3000TL LVM - 3kW 120Vac on a hand truck dolly. What would I need to connect the two units correctly? Basically, what connection do I need in between starting from connecting the wire from the Growatt down to the battery? I am confused on what amp size, fuse, and breaker are needed if needed.

Is the 4 gauge wire correct? Looking to buy the Windy Nation brand or is there a better recommendation?

Would it better to use the anderson connector? If I went with the anderson connector, what amp do I buy?

Do I need to purchase the PV combiner box? If I do, which one do I need, the 4-1 Solar Panel Combiner Box – 4 circuits to 1 (1 x 63A max output) OR the 4-2 Solar Panel Combiner Box – 4 circuits to 2 (2 to 1)- (2 x 63A max output)?

I would have to get the SOK battery in the same SOC and Will recommended the Progressive Dynamics Battery Charger 12V 45-Amp, since the SOK recommended charge current is 40a, max is 50a. Any other recommendations for battery charger?

Before connecting the battery, I remember Will using something that won’t spark when connecting the battery. What is that called and what is the correct amp size I would need?

What is the minimum solar panels needed?

Sorry if my questions are all over the place. Thank you for reading and advising!
 

Attachments

  • sok spec SK12V206-0915.pdf
    1.1 MB · Views: 9
  • growatt_spf_3000tl_lvm_series_user_manual.pdf
    16.1 MB · Views: 9
Wire gauges are set stranded and solid copper by Amp load and V. Yes 4 stranded will work, you can purchase premise cables via auto parts stores or Amazon. You can touch the positive to the over current fuse to discharge the connection. Wills videos ate spot on. Your dolly and plywood setup should go just like Will showed.
 
It sounds like you and I are doing pretty much the exact same thing. I have 2 12v SOK and the Growatt 3000 and they are mounted on a hand truck and I have 4 HQST 100w panels and 30 ft of 10awg wiring to go from panels back to the Growatt. I have much the same questions as you too. None of the videos I watch have as few components as I do. They all have added breakers and disconnects and combiner boxes and busses, etc... I want to know if I have what I need now or is there more I need to acquire? I see you only got 1 answer. What have you wound up doing?
 
I still haven't got the answers needed. I also have 4 HQST 100w panels. We are in the same state of confusion on breakers, combiner box, and busse, etc... Hopefully, someone can help us.

I did purchased a 90 amp circuit breaker 12v-48v dc to connect from the positive wire battery. I think that's correct.
 
Filter guy did reply to me and confirmed my suspicion that I don’t need any bus. He advised a 150 amp breaker between the batteries and Growatt and the Anderson disconnect on the wires going out to the pv panels, simply for convenience as it will be moved around and the Anderson just makes it easier to disconnect. This one is iffy to me. An mc4 is pretty easy to disconnect so I may not need that. I’m getting close!
 
Nice to confirm that we don't need any bus. As far as the breaker, I'm trying to understand why 150 amp. Just trying to figure out where he got the number from so I can get a better understanding. I do prefer the Anderson connection between the pv panels to the Growatt but now the question is, what is the amp that we need for the Anderson connection? Thanks for the info.
 
The HQST panels are 5 amp panels. They are 21v and I will wire mine in series to get 84v. The max the Growatt can take is 145v so we are right in the sweet spot. As for amps, running parallel will add the panel amps together but not series, so with four 21v 5 amp panels in series the output will be 5 amps at 84v. The manual doesn’t specify max amp capacity from the pv panels, but it does provide a scenario where 80 amps is called typical. This is the reason I am not too keen on a circuit breaker between the panels and the Growatt. There is no chance a little 4 panel portable diy solar generator like we are building is going to come close to this limit. If you think you want the Anderson for convenience then I would guess a 50 amp rating would be well below any level that could cause damage to the Growatt and yet still provide tons of headroom for additional panels or experimentation with parallel/series wiring. Keep in mind, I am a newb so you probably should continue for more knowledgeable advice. I have come to realize the Growatt manual was written mainly under the premise it will be hard wired into a home electrical system, which is why it calls for a breaker in front and back so it can be disconnected from power to safely service or install. The systems we are building don’t rise to that level.

With respect to the breaker between batteries and Growatt, I again will be in series so the amps will stay at 100 while the volts go to 24. The 150 number may have been suggested to be something that could allow some momentary surge required in the start up of a load without tripping. I don’t know the exact answer, but I ordered a Bussmann 150 amp breaker today so I will have that as a protection redundant to the BMS inside the SOK’s. We will definitely need to swap photos of our builds when they are finished! Good luck.
 
I think I know where the 150 Amp came from. Based on the Growatt manual, the recommended breaker on 1 unit of the Growatt (model 3DVA/24V), is 150A/32VDC.
What are using to bring both batteries in the same SOC? Are you planning on just going with the ac plug for the input and output?
I haven't had the time to build mine yet but are purchasing the items just so I have them in case of an emergency.
 
The batteries are wired in series and the breaker (which never arrived today as it was supposed to. Sunday delivery from Amazon is always hit or miss) is between the batteries and Growatt using #2awg. Yes, at this time I am just going with plugging a power strip into the output female plug and getting the power off it that way. Some people installed outlets on the wall of the vertical board, but how is that any different from zip tying a power strip with surge protector onto the board and plugging it into the female output? Besides, it will be for emergency power outage so I envision it sitting in a central place and extension cords running off it to different rooms in the house, so putting outlets on the board wouldn’t really be an advantage.
 
Filter guy did reply to me and confirmed my suspicion that I don’t need any bus. He advised a 150 amp breaker between the batteries and Growatt and the Anderson disconnect on the wires going out to the pv panels, simply for convenience as it will be moved around and the Anderson just makes it easier to disconnect. This one is iffy to me. An mc4 is pretty easy to disconnect so I may not need that. I’m getting close!
I would choose the breaker based on your battery capacity. Decide how much charge would hurt your battery and find a way to interrupt that charge with a breaker or fuse. I use a fuse on my Growatt. Right now I have a fuse on a small 48v bike battery that I don't want more than 10 amps going into it. When I get a bigger battery I will change it to the max charge I want to go into it. My next battery will be a 80 amp slow blow fuse. In my design I have a couple of 25 watt resistors in a circuit to start up the Growatt and once started I stick in the desired fuse and turn off the staring circuit with a switch.
PXL_20210816_043853261.jpg
 
The batteries are wired in series and the breaker (which never arrived today as it was supposed to. Sunday delivery from Amazon is always hit or miss) is between the batteries and Growatt using #2awg. Yes, at this time I am just going with plugging a power strip into the output female plug and getting the power off it that way. Some people installed outlets on the wall of the vertical board, but how is that any different from zip tying a power strip with surge protector onto the board and plugging it into the female output? Besides, it will be for emergency power outage so I envision it sitting in a central place and extension cords running off it to different rooms in the house, so putting outlets on the board wouldn’t really be an advantage.
Good luck with your setup! I can't wait to see your build.
 
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