Rick H Parker
Registered:1489180564 Posts: 802
Posted 1520948134
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#11
Just one thing confuses me and that is watts in series. Perhaps this will help you. Power is a rate (quantity / time) not a quantity that one can count. Power is the rate in which energy is transferred or converted to a different form of energy. Watts is the unit of measurement for electrical power. Trying to add "watts" in series is like is like trying to add the velocity of two people riding a tandem bike.
__________________ Rick H Parker Kansas, USA Electronics Engineering Technologist
Aussiemike
Registered:1520763914 Posts: 29
Posted 1520948922
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#12
Thanks Willie will make sure wires are correctly sized.
stmbtwle
Registered:1388591029 Posts: 2,877
Posted 1520975754
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#13
Watts are a unit of power, right? So with two people riding a tandem bike you get twice the power (assuming they're both pedaling). And if you gear it right, it WILL go faster.
If you have two 100w panels, that's 200w... series OR parallel.
Otherwise why spend money for the second panel?
__________________ Solar is like the wind. It may be free, but putting it to work isn't! Willie, Tampa Bay
Aussiemike
Registered:1520763914 Posts: 29
Posted 1521019208
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#14
Very good analogy.
Aussiemike
Registered:1520763914 Posts: 29
Posted 1521027947
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#15
In my schematic on post #8 the 4 x 12v panels will have an open voltage of maybe 60v. Does the following data on the back of my MPPT controller forbid me from using such controller?40A specifications: Size: Approx. 24.9x17.9x15.6cm/ 9.80x7.05x6.14" Nominal system voltage: 12/24V auto work Rated charge current: 40A Rated discharge current: 40A Battery input voltage range: 8V~32V Max. PV input power: 520W(12V); 1040W(24V) Self-consumption: ≤20mA (12V); ≤16mA (24V) Discharge circuit voltage drop: ≤0.18V Temperature compensation coefficient: -3mV/ TIA Mike
stmbtwle
Registered:1388591029 Posts: 2,877
Posted 1521029104
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#16
Assuming you mean the line highlighted in red. That is the BATTERY voltage, so you're good.
The data shown doesn't show the maximum allowable PV voltage. Can you download the manual? If there is any question you can reconfigure your solar array to 24v instead of 48v. The amps however will double to 30+A, and you'll have to size your wiring and fuse accordingly.
That would be 2 sets of 2 panels, same as the batteries.
Are you going to be using a separate inverter? While it doesn't affect the charging side, it may require heavier wiring (and fuse) between the batteries and inverter.
__________________ Solar is like the wind. It may be free, but putting it to work isn't! Willie, Tampa Bay
Aussiemike
Registered:1520763914 Posts: 29
Posted 1521030141
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#17
Thanks again Willie. I have downloaded the specs from their site and think I know the answer but will run it by you first before I make changes.
Aussiemike
Registered:1520763914 Posts: 29
Posted 1521030463
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#18
Max PV input power has no mention of 48v but
Max. PV open circuit voltage states
100V(at minimum operating environment temperature) 92V(at 25℃ environment temperature) Is that safe to assume it's ok?
stmbtwle
Registered:1388591029 Posts: 2,877
Posted 1521030989
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#19
Yes you're good. The allowable power for charge controllers is determined by the output amps to the "system" (as determined by the batteries). so you could put more power into a 24v system than 12v. When they mention "12v-24v" they mean SYSTEM voltage, and you have a 24v system.
Note the "MPPT voltage range". This is the ideal input voltage. It needs 2v more than the batteries, up to 72v. It will still work up to 100v but probably in a "safe" mode. Above 100v it may get "expensive".
At 48-60v you're right where you want to be.
I see that the recommended wire size is given too. You can use larger wire but not smaller.
__________________ Solar is like the wind. It may be free, but putting it to work isn't! Willie, Tampa Bay
Aussiemike
Registered:1520763914 Posts: 29
Posted 1521031320
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#20
That 6 AWG is for PV to controller and to battery? What distance would I be safe to use that size wire?