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diy solar

Putting together solar system for greenhouse

mcmullen7242

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Joined
May 21, 2020
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45
Location
San Diego, CA
I have 6 solar panels and 2 3.8kw battery packs from bigbattery sitting around. I own a farm and have a greenhouse that needs ventilation running 24/7 and have been running it on a small honda 2000 generator for quite some time. I am hoping to put the panels and one of the batteries to use in order to dodge running the generator during sun hours. No matter what at night between the fans and lights i will not be able to have enough battery storage on my budget so the generator will be running when the sun is down. I need 120v power.
I need an inverter and was going to go with this Growatt 3000 with 250VDC:

My panels stats are: (i have 6)
365 watts
V at Pmax:39.3 V
Current at Pmax: 9.29amps
OCV: 48.0V
SCC: 9.74 amps
Max series fuse rating 20 amps
Max system voltage 1500V

My battery is the 48v version of this and i was going to program the following into the charger (56.5V for absorb, 58V for HVD, and 49V for LVC)

My questions are:
1) With the inverter/charger having a 250VDC instead of 150VDC can i put all 6 panels in series because the Pmax is 39.3V each which would add to 235.8V or do i have to put 3 panels in series and another 3 in series, then parallel them together with an mc4 connector because of the OCV being 48V?
2) What type/gauge wire should i use for going from the solar panel mc4 connector to the inverter/charger and also from the battery to the inverter/charger?


the solar system will be powering a fan that ranges from 400watts-1500watts depending on temperature and also a water pump that is 300 watts that will only be on during watering of the plants (about 1-2 hours).
 
can i put all 6 panels in series
Depends on your lowest temperature you could get. At 77*F it will work fine
do i have to put 3 panels in series and another 3 in series, then parallel them together with an mc4 connector
that’s probably what I’d do
am hoping to put the panels and one of the batteries to use in order to dodge running the generator during sun hours
i’d use both batteries and have 3-12hrs of use time from them.
 
Ok thanks, I’ll put the panels in series parallel. I’m order to do this can I just plug the positive and negative after 3 panels are in series and the other 3 in series into an mc4 y connector and then run an mc4 extender to the inverter?

Also when the sun is down I will be powering about 1200 watts in lights on top of the fans and I don’t live on the farm so once I go and turn the lights on I don’t want to have to travel back again when the battery dies to turn on the generator.

Is there a cheap way to hook up an auto start to a generator to kick on and charge the batteries from the ac input whenever the batteries get to a certain voltage?

Also how would you go about paralleling these battery banks?
 
Is there a cheap way to hook up an auto start to a generator to kick on and charge the batteries from the ac input whenever the batteries get to a certain voltage?
No. Many solar charge controllers have the ability to trigger a generator- and shut it down. The expense is in the generator with auto start that can respond to the signal.
 
No. Many solar charge controllers have the ability to trigger a generator- and shut it down. The expense is in the generator with auto start that can respond to the signal.
i have a predator 3500 quiet generator with an electric start, do you know if that has the ability to be turned on by the inverter
 
so i will just be running the generator while lights are on till i can afford a different generator or this one craps out on me. i have about 300ft of 4 awg cables laying around so heres what i am thinking on doing:

1) i was going to solder on an anderson sb50 to 4 awg cables to connect to the battery and then run to the inverter and follow the steps in the video above but with the values i listed for programming
2) ill wire up a 20amp surge protector to connect to the ac output
3) have 3 panels in series and another 3 in series, then use an mc4 y connector (https://www.homedepot.com/p/Renogy-...8?source=shoppingads&locale=en-US&g_store=121) to parallel them together. Then i will plug two mc4 connectors into that y connnector and crimp on the 4 awg wire i have and run that the 30-40ft to the inverter

after that i believe i should be good to go. Please let me know if i got my cable size or anything else wrong. I believe my wiring should be overrated to handle it but shouldnt hurt because i already bought it and its just sitting around
 
let me know if i got my cable size or anything else wrong. I believe my wiring should be overrated to handle it but shouldnt hurt because i already bought it and its just sitting around
Over sizing cables is not a bad thing but YA! you wouldn’t go out and buy that for your purposes:)

I personally would NOT solder, I’d figure out a way to crimp and weatherproof. But that’s my thing.
 
perfect, thank you for your time and information. you have been so quick and a HUGE help. I was also thinking i should make a way to disconnect my solar array from the inverter easily and was thinking of running the cables from the panels to a 250v 50amp breaker and then run the wire from that to the inverter. is this the proper way of being able to turn off power from panels?
 
I recently added 10A breakers for my two arrays (6A tops each, 94V max) for that purpose. I have 10A fuses at the panels even though not required.
 
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