Reccomendations For Wiring My New Solar Power System

[joeyp]

My new system:

5x Grape Solar GS-S-160-Fab8 160W noncrystalline panels (http://www.amazon.com/Grape-Solar-GS...ords=grape+160)

1x Outback FlexMax 60 MPPT charge controller max 150V DC

1x Samlex PST-2000-12 2000W 12V High-efficiency pure sine inverter

4x Trojan T105-RE 6V 225AH lead acid batteries

These batteries will be divided into two pairs, with each wired in series for 12V. The two 12V pairs will then be wired in parallel for the 12V system.

I'm planning on running all five panels in series, which should be about 92.5V @ 8.65A. I'm planning on running the positive lead from the panels through one breaker before connecting to the charge controller. Then I'll have another breaker on the positive lead between the charge controller and the battery. Now, my first question is - what size breakers do you guys recommend at each of these points? And can anyone recommend a reasonably priced breaker box?

Also, the wiring diagram that came with my charge controller has a ground bus bar and then a separate DC negative bus bar that connects back to the ground bus bar. And there is a shunt in between the negative connection from the battery and the DC negative bus bar. Other than that one place in the diagram, I don't see where shunt is mentioned anywhere else in the manual. What is the shunt used for? And how do I know what size shunt to get? And is it even necessary on my 12 system?

Thanks!

[joeyp]

Batteries

I know the system needs more batteries. I'm working on it...In the meantime I will be careful not take the battery bank below 40% capacity.

[Mike90250]

Whoa ! for this size system, you should be seriously looking at 24 or even 48V. And try to stick with a single string of batteries. Doing this in 12V is just crazy. Or half crazy. see:
http://www.smartgauge.co.uk/batt_con.html for reasons for 1 string of batteries.

Design and re-design before you buy any hardware. 2Kw @ 12V is prone to fault off line from voltage sag in the wires and internal battery resistance.

5 panels is an ODD size, and will not be very easy to expand in future. Adding just 1 more panel will make things much easier. (wire 3 panels in series, then the 2 series strings get paralleled into the controller).

800W (your 5 panels) can only support about 6400wh of battery, @ 12V = 500ah.

Midnight Solar makes great combiner / breaker boxes, and sells at a really fair price 150VDC breakers.

And I won't even begin to design this any further till you have a load plan and then system plan that does not involve destroying batteries

[Sunking]

At a minimum this should be 24 volts or even 48. You are already over the max power limit of your controller at 12 volts. Another problem you have is using a PRIME number of panels. With 5 panels of this kind only gives you two option of all panels in parallel or all in series. You painted yourself into a very dangerous corner with no way out. You need to loose one panel, or gain a panel and rewire them in 2 x 3 or 3 x 2 and reconfigure batteries for 24 volts.

[joeyp]

?

"You are already over the max power limit of your controller at 12 volts"

According to the documentation on the Flexmax 60, 800 watts is fine. Maximum amps at 12V (~57) will be less than 60, and 92.5V is less than the max of 150V. Can you please explain what I'm missing?

At a minimum this should be 24 volts or even 48. You are already over the max power limit of your controller at 12 volts. Another problem you have is using a PRIME number of panels. With 5 panels of this kind only gives you two option of all panels in parallel or all in series. You painted yourself into a very dangerous corner with no way out. You need to loose one panel, or gain a panel and rewire them in 2 x 3 or 3 x 2 and reconfigure batteries for 24 volts.

[joeyp]

12v

"Doing this in 12V is just crazy."

I know that it won't be as efficient. I chose 12V for a reason. This is an emergency backup system. I need to be able to lose one battery without taking down the whole system. As configured, I can drop one battery and still continue to function, though at reduced capacity. I understand that the size of the battery bank is unusually small for the 800W input. In the scenario where this system is in full use, much of the power would be drawn immediately and not stored in the batteries.

I can go 24V. But if I do, and I lose a battery, I would be done.

Whoa ! for this size system, you should be seriously looking at 24 or even 48V. And try to stick with a single string of batteries. Doing this in 12V is just crazy. Or half crazy. see:
http://www.smartgauge.co.uk/batt_con.html for reasons for 1 string of batteries.

Design and re-design before you buy any hardware. 2Kw @ 12V is prone to fault off line from voltage sag in the wires and internal battery resistance.

5 panels is an ODD size, and will not be very easy to expand in future. Adding just 1 more panel will make things much easier. (wire 3 panels in series, then the 2 series strings get paralleled into the controller).

800W (your 5 panels) can only support about 6400wh of battery, @ 12V = 500ah.

Midnight Solar makes great combiner / breaker boxes, and sells at a really fair price 150VDC breakers.

And I won't even begin to design this any further till you have a load plan and then system plan that does not involve destroying batteries

[joeyp]

Destroying Batteries?

"And I won't even begin to design this any further till you have a load plan and then system plan that does not involve destroying batteries"

Two 3ft AWG 2/0 cables connecting the batteries and inverter, with a 250A terminal fuse on the positive connection to the battery bank. Will this not work?

Whoa ! for this size system, you should be seriously looking at 24 or even 48V. And try to stick with a single string of batteries. Doing this in 12V is just crazy. Or half crazy. see:
http://www.smartgauge.co.uk/batt_con.html for reasons for 1 string of batteries.

Design and re-design before you buy any hardware. 2Kw @ 12V is prone to fault off line from voltage sag in the wires and internal battery resistance.

5 panels is an ODD size, and will not be very easy to expand in future. Adding just 1 more panel will make things much easier. (wire 3 panels in series, then the 2 series strings get paralleled into the controller).

800W (your 5 panels) can only support about 6400wh of battery, @ 12V = 500ah.

Midnight Solar makes great combiner / breaker boxes, and sells at a really fair price 150VDC breakers.

And I won't even begin to design this any further till you have a load plan and then system plan that does not involve destroying batteries

[joeyp]

Reconfigure

Okay six panels in a 3x2 and change to 24V. But then how would I arrange the wiring and feed it into the Flexmax 60 charge controller?

Couldn't I just series all the panels together? Each panel is 18.5V. The Flexmax 60 should be able to handle the 111V DC from six panels (or 92.5 from five panels), and the solar panel max system voltage is rated at 600V DC. Couldn't I just run them all in series and then input into the Flexmax 60 and then the 24V battery bank? The CC is rated at 1500 watts on a 24V system.

THANKS to you guys for your help and responses.

At a minimum this should be 24 volts or even 48. You are already over the max power limit of your controller at 12 volts. Another problem you have is using a PRIME number of panels. With 5 panels of this kind only gives you two option of all panels in parallel or all in series. You painted yourself into a very dangerous corner with no way out. You need to loose one panel, or gain a panel and rewire them in 2 x 3 or 3 x 2 and reconfigure batteries for 24 volts.