Grid support Xantrex XW4024 Help

Re: Grid support Xantrex XW4024 Help

Deacon,

Welcome to the wonderful world of Xantrex nebulosity. I have a very similar setup as yours so lets see if i can help. You have to have grid support enabled and also in advanced mode, you should have grid support volts set to something like 25. This setting is very weird and is supposed to be the minimum voltage the system will discharge the batteries to before reverting back to AC passthrough. That being said, you will find that the voltage will go far below that voltage you set depending on temperature and some weird hysteresis algorithm they compute. You will have to start off with this voltage set pretty high and monitor when the system goes into AC passthrough. This will allow you to characterize the system and walk the number down to where it is performing as you like. You will also find that you are cranking this number up and down depending on if it is going to be forecast cloudy or sunny for a few days. so as not to run out of batteries. Once you master grid support I will tell you how to set up the SCC for "automatic" mode.

Joe

Re: Grid support Xantrex XW4024 Help

deacon wrote: »

Joe,
Thanks for the insight. Right off the batt I have a problem trying what you said. If I attempt to change the grid support voltage to anything lower than 26.0 volts, I get an error message saying value failed to change, try again. Maybe I should do a cold boot of the whole system and try again.
Thanks!

Well a cold boot would be the last resort and the recomended Xantrex tech suppoprt remedy.

deacon wrote: »

I just checked the XW60 SCC manual from end to end and it does not mention automatic mode. Documentation leaves a lot to be desired.

I am not running a C60, I am running the XW SCC and I am not sure how the software works but I think the automatic mode is more in the 4024 rather than the SCC.

deacon wrote: »

Joe,
What indicators or meter readings in the SCP or inverter let you know that grid support is working. My SCP says grid support is enabled but it isn't working at all.

First lets check a few things,

Under Inverter check the following:

LBCO = 22.5 V
LBCO delay = 10 sec
HBCO = 35 V
Search watts = 0
Search delay = 2 sec

Under Charger:

Recharge V = 25.5

Under Grid Support:

Grid support voltage = 25.5 V
Sell = Disabled
Max sell A = 0
Load Shave = Disable
Load shave amps = 0

Now on the home screen of the XW-4024 in the right side, the display should switch from ACpassthrough to GridSupport. You should also see on the lower right that the AC1 is considerably less than the load number.

Some of these settings prevent other settings from being entered, hopefully if you set things up as above the thing will go into G.S. mode. Let me know what happens and I will try to help you more.

Automatic mode is set when you enter Grid Support Volts = 32, in this mode, the 4024 will only support the grid when the batteries are at 100%. If you set GSV = say 25.5 V then the 4024 will support the grid by depleting the batteries down to something near the GSV value.

You would think that this thing would supply a real error code to let you know why the value failed to change but I guess that is just more of the wonderfullness of X.

Good luck,

Joe

BTW, my system is 8xSW-235 panels (1440 stc), 1xXW4024, 2xXW SCC, 8xL16REB, AGS & gateway, Honda EU5000I gen.

Re: Grid support Xantrex XW4024 Help

Deacon,

At this point, I have given up on X (now Schneider) tech support. Depending on who you get on the other end its hit and miss that the call will be a waste of time.

In any event, I am not seeing my meter spin any faster when in grid support. Are you absolutely sure that SELL is disabled? I know for a fact that my electric bill went from $120 to $20 per month when I do grid support so I know it works.

As far as the grid support volts goes, this is a real important number. It more or less determines how low your inverter will drag the batteries in grid support mode. I find myself jacking this value all over the place depending on the weather.

For example, if I know it is going to be cloudy or if the power is likely to go off because of a storm, I set grid support volts to 32. Then if the grid fails, I have a fully charged bank to run things on. If I know it is likely to be sunny then I will set the grid support to around 24.7 volts. By doing this, I will run my bank down to about 85% over night and the PV will recharge the bank without drawing from the grid. If I screw up and the bank goes down to about 80% and there is no PV then it will charge from the grid in the wee hours of the morning.

Let me know if I can answer anything else for you Deacon,

Joe

Re: Grid support Xantrex XW4024 Help

RCinFLA wrote: »

Not sure of your definition of grid support. The XW inverter output is hard-wired to ACout. There is a relay that connects the ACout/Inverter node to ACin.

In grid suppliment support, the grid connect relay is engaged and the inverter operates in parallel with the grid. If the battery voltage is attempted to be raised above XW4024's charge regulation set point the inverter will suck off any excess current trying to take the battery above the XW4024 set value and convert it to AC at the Grid/ACout node.

With the XW charge controller and Xanabus, the charge controller battery regulation voltage (float) is sub-serviant to the XW inverter's setting, meaning it normally will push all the solar power it can to the batteries knowing the XW will maintain float regulation voltage.

If the ACout load cannot consume the PV injected current from the battery node, and sell is not enable, then the charge controller will be told to back down the battery push to avoid allowing the battery float voltage setting to be exceeded.

You should be able to read ACin and ACout current. With PV power injection, the ACout current should exceed the ACin current, with the difference being made by the inverter and injected into the AC node, assuming there is another battery charging source that is injecting current into the battery node.

This is similar to load shaving where you set an intentional limit to the maximum ACin current and inverter/batteries supply any additional needed current for a higher ACout load. In this case the low battery limit is important to avoid excessive battery drain, in contrast to grid support which only suppliments ACout if battery voltage is higher then XW inverter charge float voltage level, so there is no issue with battery discharging.

There is another mode where no grid power is drawn and ACout power is totally taken from battery node. One use of this function is to avoid drawing on grid during peak grid rates when time of day tariffing option is selected from local power company.

I have never been able to reduce my grid draw to zero, please elaborate more on this other mode. The only way I can get my grid draw to zero is to disconnect from it manually.

Re: Grid support Xantrex XW4024 Help

Deacon,

I think we have a terminology issue here. Being grid tied is not the same as selling back. From what you have posted, I am thinking your XW system is not in your house but in a barn. The tie from your barn to your house should NOT, repeat NOT go through your electric meter. Only the grid connection (to AC1) should be meterd by your electric company.

The only thing your electric company has to know is if you choose to sell back power, thats a whole can of worms. So to recap, the grid goes through the meter and into AC1, The output of the inverter drives your AC loads, if you have a generator, it goes into AC2.

Joe

Re: Grid support Xantrex XW4024 Help

Deacon,

Net metering (sell) will require a new meter and yes if you have an "old" meter it will register power in either direction as a charge. There is no way that I am aware of that the XW can push power back on the line with SELL disabled.

My system is grid tied but I never enable SELL mode. I have only seen my grid consumption go down with grid support enabled. If you are sure that the electric companies meter is only connected to AC1 and that SELL mode is disabled, I can not see how your meter is even seeing your AC loads. When this is happening, what do you see on the meter screen? Do you see load power being significantly higher than AC1 power? If you do and the meter is still spinning faster, you either have a wiring error or the XW is doing something very strange.

EDIT: OK I re read your last post. I think I see the problem. Check me: You have a grid connection at your house, this grid conection goes through the electric company meter and connects to your house loads? and also to a 200 foot run to the barn? You are trying to push power back up the 200 foot run to supliment you loads? Is this correct? If so, then your meter will see the XW output as GRID power and charge you for it. The grid connection should only come from the street through the meter and into AC1, the house should only be connected to the inverters output terminals. Am I understanding your setup or am I full of it?

J

Joe

Re: Grid support Xantrex XW4024 Help

jeffkruse wrote: »

I am about to use the Grid Support feature on my XW4548. The way I understand it (and want it to work) is that the Grid will “support” my batteries when the voltage goes below the voltage setting.

In my case I want to use my batteries for most of my power and only use the grid when my battery voltage goes below say 49V.

I can not sell back to the grid otherwise I would do so.

Jeff,

Grid support is when the inverter uses battery energy to support a percentage of your AC loads. Your question deals with the charger portion of the 4548. If you set the recharge volts to 49, the battery charger will enter bulk mode when the battery voltage falls below 49 volts.

Re: Grid support Xantrex XW4024 Help

jeffkruse wrote: »

I believe it’s the other way around.

The batteries are the only source of power until they drop below the set point. Then the grid is switched in and no more draw from the batteries. I will have the Inverters battery charger OFF so they won’t charge from the grid.

Jeff, My 4024 does not operate that way, In grid support mode, the batteries support the grid. There is power drawn from the grid always. The only way I have found to eliminate all grid draw is to pull the disconnect. Then the 4024 goes into invert mode.

With my inverter if I draw more than 4500W the grid will supply the overage. This is what Xantrex told me. Say I draw 10,000 Watts, 4500 would come from my batteries and the rest (5500W) would come from the grid. But I don’t plan on doing this.

That is not the way mine works, If I am grid tied, then depending on the state of charge in the bank and the grid sell voltage, the AC1 draw is anywhere from 100 - 200 watts. My loads are limited to 4000 watts (inverter limit), so say my bank is at 100% and I have grid support volts set to 25V, my inverter will pull about 100 watts from AC1 and the rest from the battery. As the battery capacity drops, the inverter shifts more and more of the load to the AC1 input until eventually is is all coming from AC1 and then the inverter is in AC passthrough.

I cant sell to the grid. I want to use my system to supply all of my power but I also don’t want the batteries to go to low – say 30 – 40% DOD.

I run mine the same way but dont run the daily DOD past about 20%

I think if I set the grid support voltage to 49 or 49.5 I will rarely use grid power and keep my batteries above 60% charged.

I thought you were running a 4024??? if so, why would you set the voltage so high? It sounds like my system is not behaving like yours.

Please correct me if I have this wrong.

I hope I am not confusing the issue:D

Re: Grid support Xantrex XW4024 Help

jeffkruse wrote: »

My Grid Sell will be OFF. Is yours set to off?

Yes.

I have a 4548, 4500 watts at 48V.

Oh OK, the title of the thread is XW4024, I got confused.

Xantrex and my salesman told me it would work. :roll:

Dont get me going.

Re: Grid support Xantrex XW4024 Help

Before I start, I would like to say I think the XW inverters are pretty good units.

Having said that, I think the XW is an example of software designers run amuck. Naming conventions and interaction between functions make setup very confusing.

The op's manual is absolutely horrible.

If you start with an understanding of the basic hardware functionality it can help understand the mutated explainations in the op's manual.

Refer to the simpified attached diagram during following descriptions.

The XW inverter is a bi-directional inverter. This means the inverter can push or pull power to or from the batteries. It has a large transformer that has a high frequency pulse width modulated MOSFET H-bridge driving the primary side at battery voltage and a center tapped secondary winding for the 240 vac output. (actually two individual 120 vac secondary winding configured in series).

The high frequency PWM creates the 60 Hz sinewave and regulates the voltage level and phase of the inverter. The difference between pushing or pulling power to the batteries is just a slight modification to the PWM signal creating the voltage level of the 60 Hz sinewave output. It can move from charging to supplying ACout on the fly.

The filtered sinewave output of the inverter is hard wired to the ACout node connection. There are 60 amp rated power relays on the AC1in and AC2in that connect one of the two ACin's to the ACout output node.

There are voltage senses on ACin connections, a common ACin current sense after the power relays, and voltage and current senses on the inverter output. The senses are all AC vector capable meaning they can be used to check voltage and phase match between ACin port and Inverter/ACout port. This also allows absolute power and power factor calculations.

With these voltage and current senses the computer can calculate and control the power flow directions on any of the ports.

Before either of the two power relays are engaged, the inverter voltage and phase must be slewed to match the ACin (blinking green LED). Once it does, the relay closes and inverter is running in parallel with the ACin (green LED turns solid).

Beyond this basic hardware, everything else is purely software.

I read and re-read the op's manual to try and understand what 'Grid Support Enable' means. I have concluded that it only means that if it is NOT enabled, the inverter is not allowed to push out power from batteries to ACout node. When it is not enabled the inverter can only charge the batteries while connected to grid. Again this is only slight PWM control on primary side to prevent inverter from pushing out power based on the vector multiplication of the current and voltage sense measurements on the inverter output connection. The PWM has to be constantly adjusted to prevent inverter from pushing out power as the battery voltage and line voltage varies.

The inverter power outputting seems to have three modes while inverter is running in parallel with ACin (inverter syncronized and power relay engaged).

1) Grid Support Enabled, Sell disable, Load Shave disabled. - Inverter will push power to ACout node if battery voltage goes above Grid Support voltage setting. There are other interactive conditions to this. Obviously if battery is going through its first and second phase of charging it won't be pushing power out. Being that Sell is not enabled, any pushed power to ACout node must be consumed by ACout load. No power will be allowed to go back up AC1in port. If ACout load cannot consume the pushed power then the battery voltage will be allowed to rise. Presumably the PV controller will take over the regulation and prevent battery voltage from continue rising.

2) Grid Support Enabled, Sell disabled, Load Shave enabled. - Exactly like above with the difference being inverter will be allowed to push power at lower battery voltage, down to 2 volts above LBCO setting.

3) Grid Support Enabled, Sell Enabled, Load Shave Disabled. - Just like like 1) with allowance of any excess pushed power (beyond consumed by ACout load) to exit out AC1in port to grid. Range of battery voltage is active at Grid Support voltage, deactivate at Grid Support voltage - 0.5 vdc.

Keep in mind the inverter AC power output push is continously variable in strength. At Grid Support voltage it just barely starts to push. As battery voltage goes up (just a little) it pushes harder.

Re: Grid support Xantrex XW4024 Help

Saturday I hooked up the grid to my Xantrex 4548. I Enabled Grid Support and set it to 49V (the lowest setting allowed) . Sell is disabled, Load Shave is Disabled, Charger is Disabled.

It works but not the way I expected(hoped). I hoped it would use only battery power until the battery voltage was lower than the set point then it would use the grid.

It uses the grid ALL the time but only around 50 – 200 Watts. The rest is supplied by the batteries. If I use 200W then 100 comes from the Grid and 100 comes from the batteries. If I use 1000W then 200 comes from the Grid and 800 comes from the batteries.
If I only use 70W then it all comes from the Grid even when there is plenty of sunshine and the batteries are at 58Volts!

I also Tried turning Load Shave on and setting to 0Amps but the result is the same.

After two nights of use it looks like 1/3rd of my power will come from the grid and all the excess solar power will be lost.

I wish there was a way to make this work the way I want it to.

Re: Grid support Xantrex XW4024 Help

I have been through this with the tech support more times than I care to count. It actually states in the manual that grid current is reduced to zero.

"If the battery voltage is above Grid Supp Volts, then the current taken from
the grid is reduced to zero (see Figure 3-7, “Peak Load Shaving Mode” on page
3–23). This maximizes the renewable energy for AC load usage."

I have never been able to get my grid power to zero either. The Software is broken and they have no intentions of fixing it.

ETA: you can get your grid support volts below 49 by reducing the LBCO in the inverter menu. (Yeah they dont tell you that either)

Re: Grid support Xantrex XW4024 Help

For the measurements I used what the Xantrex System Control panel was telling me and my trimetrix battery monitor.