24v Solar setup for bus
- Thread starter jonoslade
- Start date
Thanks, I am looking at the Giandel 24 Volt 2000W Pure Sine Wave the are claiming this in the FAQ:
Q: How many amps should the input fuse be?
A: We don't recommend to put inline fuse. The inside fuses will protect the inverter.
By GIANDEL on May 8, 2019
The manual say it has 4 30A fuses but would happily add one for extra protection. Any recommendations on the size since the user manual doesn't have one?
John Frum
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2000 ac watts / .85 conversion factor / 24 volts low cutoff / .8 fuse headroom = 122.549019608 fuse amps
You need a fuse on the inverter positive wire as close to the battery positive terminal as possible.
Its goes as close as possible to the battery terminal to minimize the chance of an upstream short.
John Frum
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The pv side is not my forte @MisterSandals you are hailed.
MisterSandals
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I saw this earlier and thought it just needed a breaker before inverter as smoothJoey mentioned.
i did the Voc math and recall it added up to 133.x Voc with a max input voltage limit of 150. Was trying to figure the math on voltage increases from temps dropping below 25 dec C.
Thermal coefficient perhaps listed on your panels? around .4% volts per degree below 25 deg C.
So 17v increase would possibly kill your SCC.
17v / (133 x .004) = 32 deg drop below 25 C
So your array voltage is safe down to -7 deg C (19F).
unless you are in the tropics, 3S probably not a good idea for an SCC that is limited to 150v input.
2S3P is an option too.
i did the Voc math and recall it added up to 133.x Voc with a max input voltage limit of 150. Was trying to figure the math on voltage increases from temps dropping below 25 dec C.
Thermal coefficient perhaps listed on your panels? around .4% volts per degree below 25 deg C.
So 17v increase would possibly kill your SCC.
17v / (133 x .004) = 32 deg drop below 25 C
So your array voltage is safe down to -7 deg C (19F).
unless you are in the tropics, 3S probably not a good idea for an SCC that is limited to 150v input.
2S3P is an option too.
John Frum
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Nice, make sure the wire between the battery and the inverter is 4 awg or better with 105C insulation.
Late question- Is the bus starter voltage 24v?
I assume it is and that is why you have gone with 24v. However some odd larger vehicles use 12v. If so, it may be better to stay with 12v.
MisterSandals
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Or is this 24v system for the "back of the bus" only? Which is ok too, just a good thing to consider when evaluating your design.
Then alternator charging for this bank too?
MisterSandals
Participation Medalist
I am seeing 6awg would be good for the inverter being within 4ft of the battery to be acceptable.
Voltage Drop Calculator
This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.
www.calculator.net
John Frum
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2000 ac watts / .85 inverter efficiency / 24 volts low cutoff = ~98 dc ampsI am seeing 6awg would be good for the inverter being within 4ft of the battery to be acceptable.
View attachment 53981
Voltage Drop Calculator
This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.
~98 amps / .8 fuse headroom = ~123 fuse amps
Which is right on the line for 6 awg but since the drawing shows a 150 amp fuse 4 awg wire is required.
