Will this work

czars

I am an experienced electrical contractor with only a little PV experience. A friend has asked me to help design and install a grid tied, battery backed-up, PV system at his home. He has purchased an Xantrex XW-4548 Inverter/Charger, an XW E-Panel, an Outback Flexmax 80 Charge Controller as well as solar panels and a combiner.

He wants the PV array to charge the batteries and then automatically use the Inverter/Charger to use the battery power to create AC power to offset his usage from the power grid when the grid is up and to use the batteries to provide power through the inverter to selected circuits when the grid is down.

I am questioning whether or not or how the Inverter/Charger and the Charge Controller will work together to provide the system operation that he desires. I would welcome input from anyone.

Cariboocoot

Re: Will this work

Normally an XW is set to charge the batteries first, then sell any surplus solar production to the grid. They work well that way, once you get them set up and working. Using battery power instead of utility isn't very economical, even if used for "time shifting" rates. As a rule, battery based electric comes at a cost of around $1 per kW hour. It is doubtful that he will save that much by switching between night rates and day rates.

There have been discussions of this around here before, but I can't for the life of me think of a simple way to search for them without coming up with every XW thread.

czars

Re: Will this work

Thanks for your reply. Would my friend be better off utilizing a Xantrex Charge Controller that can communicate with the Inverter/Charger via the Xanbus?

solarix

Re: Will this work

Here's the deal. The charge controller is what charges the batteries (almost all the time - there may be cloudy days where the XW4548 has to help out charging them using grid power) The inverter then uses the battery energy to power his dedicated loads. If the battery becomes too full, then the inverter exports the energy through its grid connection. This way the charge controller can work its little heart out maxing the harvest from the PV array. The inverter has two AC connections - one for the dedicated loads (which it keeps powering during grid outages) and one for the grid connection. The XW system is what I call a hybrid inverter and you get the best of both the on-grid and the off-grid systems and you don't need as big a battery bank and the batteries last a lot longer than in a off-grid only system.

Cariboocoot

Re: Will this work

I think he'd be better off with the matching charge controller. Always nice when the equipment can talk to one another and agree on things.

The XW has another AC connection, BTW: AC 2 IN I think it's called. That's for the back-up gen just in case the grid goes down, the clouds roll in, and the batteries go dead. Over-all it's a good system. A bit cantankerous, judging by the XW posts. And it seems you need a larger battery bank than what Xantrex says.

Solar Guppy

Re: Will this work

Your configuration is how most use the XW series when gridtie

Please read this thread and understand the battery requirements

http://forum.solar-electric.com/showthread.php?t=11709

Dave Angelini

Re: Will this work

My input is it is really just plain wrong to mix an XW inv/chg with an Outback CC. You have lost all the designed-in features of a networked system and made it harder on the owner.