New System Fuse/Breakers & Parallel or Series

SolarFail

Hi all, I recently attained some property that had two systems already installed on two different buildings, a 12v and a 24v. One building is being destroyed, so i essentially have two different systems to use to make one system.

I have the following items:

Panels - 100w - 5.5a x 8
Batteries - 6v forklift x 8
Controller 1 - 12v 100amp Standard (Missouri Wind & Solar)
Controller 2 - 12v/24v 40A MPPT (EPever Tracer4210A)
Inverter 1 - 12v 2000w inverter/charger
Inverter 2 - 24v 1500w inverter/charger (Broken)
Fuses/Breakers - None

I've only done small setups before, both of these systems are much larger than anything I've worked with. The 12v system was wired in Parallel, the 24v system was wired both parallel and Series.

What i'd like to do is make one system, using the 8 panels. The 40A MPPT controller states that it has rated charge power at:

12v - 520w / Max 1560w
24v - 1040w / Max 3120w
Max PV open circuit voltage is 92v @ 25c, 100v @ minimum operating environment* (EDIT)  (Does this mean that i could wire the 8 panels in series to get 96v, and the controller will convert it to what i need, either 12v or 24v system?)

A new 24v inverter charger is quite pricey, so i was thinking of just hooking up a 12v system since i have everything. So what i'm unsure of, is whether i should/can hook up the panels in series, or keep them in parallel? And where to install fuses/breakers, what type of fuses/breakers should i get, and how to determine what size? 

Horsefly

First off: Your handle is going to be bad luck. 

If you are going to go with a 12V system, you are going to configure your 8 6V forklift batteries are 4 parallel strings of 2 batteries. I don't have a clue what AH those batteries are, so it might be helpful if you could post it.

First off, it sounds like that MPPT charge controller can't take all 8 panels, since the total - in any series parallel configuration - would exceed the 520W spec.  You might be able to run 4 panels in series, as I would expect those panels are probably Vmp = 18V. Four in series would be 72V, which may be ok.   You probably need to check the hyper Voc for those panels - That's the open circuit voltage at the coldest possible temperature at your location. It will be higher than the 18V, and you want to make sure that putting 4 in series doesn't ever exceed 84V or you will fry your CC.

You'll need some breakers on the input to the CC, the output of the CC (to the batteries), and between the batteries and your inverter. The one on the input to the CC should be based on your panel series / parallel configuration, for the maximum current at that voltage the CC could handle. I'd need more info on how you are going to configure them to give you that size.

The CC is rated for 40A, so the breaker on the output of the CC needs to be 1.25x 40A, or 50A. 

The 12V inverter is rated 2000W, so the max current at 12V would be 2000 / 12 = 166.7A. The breaker there should be 1.25x 166.7 which you would round to 200A.

Vic

Hi SolarSuccess,  welcome to the Forum,

You probably have the manual for the Tracer Charge Controller (CC),  but here is a Linkwww.epsolarpv.com/en/index.php/Technical/downloadF/id/678

Page 9 shows a table for the number of PVs suggested per string.

Please give us the spec for Voc of your PVs
Please give us manufacturer and model number of your batteries.

You would probably be best off starting with a 24 V inverter,   but  good system design always starts with the LOADS that the system needs to supply,   the peak power needed,   the purpose of the system,   and other details.

You will want an input breaker (from PVs),  and a battery breaker for the CC.

You will want a large breaker between the battery and the inverter.   A 2000 Watt inverter is fairly large,  will need large cables on the batteries and to the inverter,   and usually will have a fairly high idle current.

The Tracer manual states that on a 12 V system,  it is best to run PVs in strings to two panels.   This would customarily mean that with four strings (if you used all of your PVs)  that you would use a Combiner that had four breakers  --  one for each string ...

So,  please give us more details of your loads,  and expectations for the system.

Others here will add more.   Vic

Estragon

Definitely start with loads and expectations. I'd add that with the batteries having lived life so far as separate banks (2s2p12v and 4s24v?), they may or may not play well together in a nwe configuration. If forklift, I assume flooded, so SGs on each would be helpful.