How to add solar panels to a battery back up system? yes this is an odd system...

[rgabriel4566]

Hey I currently have a big battery bank that I use for when the power goes out with the plan to get solar one day. Today is that day! I currently have a XW6048 inverter and a XW MPPT60 charge controller a friend is going to sell me an additional inverter and charge controller (Xantrex Freedom SW 2012 Inverter/Charger and Xantrex XW MPPT80 600 High Voltage Controller). I have 35 ecosolargy 230w panels to install. My question is in the wiring... Because I have 8000 watts worth of inverter and 8300w of charge controller but one CC is 4800w and the other 3500w and one inverter is 6000w and the other is 2000w. So I cant just wire them like two different systems I will have to use them simultaneously. Does anyone have any idea how I could do this??? Thanks!

here are the specs on all the stuff I have:

http://www.solarpanelstore.com/solar-power.xantrex-inverters.xantrex_xw.xw6048.info.1.html

http://www.starmarinedepot.com/xantrex-freedom-sw-2012-inverter%2fcharger.html

http://www.solarpanelstore.com/solar-power.large-charge-controllers.xantrex_charge_controllers.xantrex_xw_cc.info.1.html

http://www.solarpanelstore.com/solar-power.large-charge-controllers.xantrex_charge_controllers.xantrex_xw_cc_80.info.1.html

http://www.solardesigntool.com/components/module-panel-solar/ecoSolargy/585/TWES-%28230%2960P/specification-data-sheet.html

[Naptown]

I would isolate and run as two separate systems with the XW set up to sell back to the grid.
You would have to check with Xantrex to see if the systems can be paralleled

[inetdog]

I would isolate and run as two separate systems with the XW set up to sell back to the grid.
You would have to check with Xantrex to see if the systems can be paralleled

The general rule of thumb, which still needs to be double checked for specific circumstances, is that you must never connect one array of panels to two different MPPT devices, whether they are battery chargers or inverters. I do not know of any devices in this class that can share a common PV array even if they are from the same manufacturer and can intercommunicate.

The other side of this is that there is generally no restriction on how many inverters you can operate off one battery bank, and they do not even have to have compatible settings. But if you have both a grid tie inverter and an off grid inverter, you cannot connect them to the same AC load wiring unless they are specifically designed to coordinate.
Both Xantrex and SMA have products that support this kind of coordination (often referred to as an AC-coupled hybrid system.)

One grey area comes when you want to have two independent CCs charging one battery bank. That will generally work UNLESS the combined current of the two CCs in Bulk mode is more than the battery bank can handle. Dealing with that situation again requires coordination.

[rgabriel4566]

[QUOTE=inetdog;90715]The general rule of thumb, which still needs to be double checked for specific circumstances, is that you must never connect one array of panels to two different MPPT devices, whether they are battery chargers or inverters. I do not know of any devices in this class that can share a common PV array even if they are from the same manufacturer and can intercommunicate.

Is there a way that I could have 3 strings of 7 (230w panels) on one CC and 2 strings of 7 connected to the other CC then connect both CC's both to the battery bank then to both inverters?

[inetdog]

[QUOTE=rgabriel4566;90823]

The general rule of thumb, which still needs to be double checked for specific circumstances, is that you must never connect one array of panels to two different MPPT devices, whether they are battery chargers or inverters. I do not know of any devices in this class that can share a common PV array even if they are from the same manufacturer and can intercommunicate.

Is there a way that I could have 3 strings of 7 (230w panels) on one CC and 2 strings of 7 connected to the other CC then connect both CC's both to the battery bank then to both inverters?

Connecting two CCs to one battery bank is not an issue as long as the combined amperage of all of the controllers in Bulk mode at the same time is not to much for the batteries.
Same for two inverters to one battery bank as long as together they do not not draw too much current from the battery bank.
Going from two independent inverters to one load is not a problem for Grid Tied, but would require coordination between the inverters for off-grid operation.