Should we have a Hybrid Solar section?

[wgollie43]

Outback Radian GS4048A using GridZero

I am a newbie in this Solar stuff but not to electronics. I have 12 Sharp 250w panels. I am using Outbacks batteries 200REs. 12 of them in a 48v configuration. GridZero is Energy Balancing using Advanced Battery Charging. There are a lot of questions I have about what the system is doing when I look at it(Understanding the Mate3 displays).
It would appear that Outback did a great job on the GridZero design but the displays are not intuitive. Then again it could be my lack of understanding what is being displayed.
If anyone knows the GridZero I will post pictures of the Mate3 display for response.

[Raj]

I am a newbie in this Solar stuff but not to electronics. I have 12 Sharp 250w panels. I am using Outbacks batteries 200REs. 12 of them in a 48v configuration. GridZero is Energy Balancing using Advanced Battery Charging. There are a lot of questions I have about what the system is doing when I look at it(Understanding the Mate3 displays).
It would appear that Outback did a great job on the GridZero design but the displays are not intuitive. Then again it could be my lack of understanding what is being displayed.
If anyone knows the GridZero I will post pictures of the Mate3 display for response.

Hi wgollie43,

Your system and application is new and under warranty, I suggest you go to the Outback forum, register and ask your questions. They will answer. That is what I did. Here is the link. http://outbackpower.com/forum/
Of course you can also call their support line.

Raj

[wgollie43]

Hi wgollie43,

Your system and application is new and under warranty, I suggest you go to the Outback forum, register and ask your questions. They will answer. That is what I did. Here is the link. http://outbackpower.com/forum/
Of course you can also call their support line.

Raj

Raj, I done that and have aske questions on the OB forum. But it appears I may be on the bleeding edge for those using GridZero.

Below is the latest of my OB postings:

-------------------------------------------------------------------------------------------------------------------------------------------
I am still trying to determine if my GS4048A is doing what it is supposed to do. I just don't get the feeling the Radian is doing what it is suppose to do in GridZero mode. Total cumulative AH created from my batteries for the last week is 1WK.
In the early mornings, I get up at 4:45 for work, I have a reading light on to read the morning paper. I go out to the garage and the home screen shows that the source is coming from the Grid not the batteries. Batteries are at 100% @ 52V. Why is the system not using the batteries?

[Raj]

Raj, I done that and have aske questions on the OB forum. But it appears I may be on the bleeding edge for those using GridZero.

Below is the latest of my OB postings:

-------------------------------------------------------------------------------------------------------------------------------------------
I am still trying to determine if my GS4048A is doing what it is supposed to do. I just don't get the feeling the Radian is doing what it is suppose to do in GridZero mode. Total cumulative AH created from my batteries for the last week is 1WK.
In the early mornings, I get up at 4:45 for work, I have a reading light on to read the morning paper. I go out to the garage and the home screen shows that the source is coming from the Grid not the batteries. Batteries are at 100% @ 52V. Why is the system not using the batteries?

wgollie43,
Since this is a grid tie mode, the grid is always available to augment or stand-in for the inverter with power up to 15 amps per leg at 240 VAC.
Grid Zero prioritizes battery over grid power, so the inverter will use battery power until it reaches the DOD volts setting.
So, it sounds like your depth of discharge volts setting has been reached, and the inverter is waiting for the batteries to be recharged.
This may be caused by insufficient charging during daylight hours or your loads have taken the batteries down to the DOD volts setting.
This setting is determined by the capacity of your battery bank, the voltage, and how much capacity you want available for backup power.
A lower setting will make more of the battery capacity available for nighttime use. A higher setting will make more capacity available for backup power in case you lose the grid at night.
For your battery bank, three strings of four batteries each for 538 AH at 48 volts, a conservative setting might be what ever voltage represents about 30% DOD on the bank.
I am not that knowledge about AGM lead acid chemistry, so some of the other members of this forum may be able to chime in with that approximate voltage.
Anyway, with this setting (volts equaling 30% DOD) you should have about 150 amp hours for overnight use. About 7 KWH I believe. Obviously this is only true if the battery bank was completely charged by PV during daylight hours.
Should the battery bank be 52 volts at 100% capacity? I can not answer that. You may want to take your DOD volts setting down 1 volt and see what that does.
So...What do you have your DOD volts and your DOD amps set to?
Also, Take a look at this document and then get back to me with those settings. http://www.outbackpower.com/download...BC_2-18-14.pdf

Rick

[wgollie43]

wgollie43,
Since this is a grid tie mode, the grid is always available to augment or stand-in for the inverter with power up to 15 amps per leg at 240 VAC.
Grid Zero prioritizes battery over grid power, so the inverter will use battery power until it reaches the DOD volts setting.
So, it sounds like your depth of discharge volts setting has been reached, and the inverter is waiting for the batteries to be recharged.
This may be caused by insufficient charging during daylight hours or your loads have taken the batteries down to the DOD volts setting.
This setting is determined by the capacity of your battery bank, the voltage, and how much capacity you want available for backup power.
A lower setting will make more of the battery capacity available for nighttime use. A higher setting will make more capacity available for backup power in case you lose the grid at night.
For your battery bank, three strings of four batteries each for 538 AH at 48 volts, a conservative setting might be what ever voltage represents about 30% DOD on the bank.
I am not that knowledge about AGM lead acid chemistry, so some of the other members of this forum may be able to chime in with that approximate voltage.
Anyway, with this setting (volts equaling 30% DOD) you should have about 150 amp hours for overnight use. About 7 KWH I believe. Obviously this is only true if the battery bank was completely charged by PV during daylight hours.
Should the battery bank be 52 volts at 100% capacity? I can not answer that. You may want to take your DOD volts setting down 1 volt and see what that does.
So...What do you have your DOD volts and your DOD amps set to?
Also, Take a look at this document and then get back to me with those settings. http://www.outbackpower.com/download...BC_2-18-14.pdf

Rick

Thank you for your response. My DOD Volts is 50V and my DOD amps is 12.
The document you referenced above I already have read and used it to program the Radian. When I go up this morning the batteries read 51.9. So I am thinking I should have been using the batteries. What I did not look at was the state of the system this morning. That is was it inverting or passthru. Will check it in the morning and let you know what status is being reported.

[wgollie43]

Thank you for your response. My DOD Volts is 50V and my DOD amps is 12.
The document you referenced above I already have read and used it to program the Radian. When I go up this morning the batteries read 51.9. So I am thinking I should have been using the batteries. What I did not look at was the state of the system this morning. That is was it inverting or passthru. Will check it in the morning and let you know what status is being reported.

I have made a change to the DOD per your suggestion. I lowered the DOD Volts to 30%. Now the setting is 49.2. As soon as I made the change the system started using the batteries. Can you explain why all of a sudden it started using the battery when I made this change. I am a EE and feel like a dummy. I understand electronic curcuits but this battery solar stuff has a different twist.

[Raj]

I have made a change to the DOD per your suggestion. I lowered the DOD Volts to 30%. Now the setting is 49.2. As soon as I made the change the system started using the batteries. Can you explain why all of a sudden it started using the battery when I made this change. I am a EE and feel like a dummy. I understand electronic curcuits but this battery solar stuff has a different twist.

Hi wgollie43,

Good, glad we are getting results.
Well, like I said, I don't know the range of voltages that reflect the usable capacity of your AGM's. I do know how the Radian running the GridZero app should work. I would say that if you moved the DoD volts set point from 50V to 49V and the inverter started then the GridZero app is responding to the battery capacity dropping below 100%. I recommend doing some testing. Record the voltage and battery capacity when the inverter cuts off. Then drop the DoD voltage setting again. Record the same again. Try tweaking it until the battery capacity reaches 70%, when the inverter shuts down. Testing will show you where the possible set points really are, whether it is 20, 25, or 30% DoD.
Also, how many KWH's per day average have you been producing since you had your system installed? This has to do with the DoD amps setting, but we'll get into that next time.

Rick

[Mike90250]

As long as you understand the math between buying power from the grid (maybe 30 cents per KWh) and the wear/tear decrease in life of the batteries (you know how much they cost, and that the deeper the discharge, the fewer cycles) for battery replacement costs. So for the $10 you may save in a month on "store bought power", it may cost you $80 in eventual battery replacement costs.

[Raj]

[QUOTE=Mike90250;131242]As long as you understand the math between buying power from the grid (maybe 30 cents per KWh) and the wear/tear decrease in life of the batteries (you know how much they cost, and that the deeper the discharge, the fewer cycles) for battery replacement costs. So for the $10 you may save in a month on "store bought power", it may cost you $80 in eventual battery replacement costs.[/QUOTE

Hello Mike,

I have to say that if I were buying a standard grid tie system I would consider it an investment and would be calculating a return on investment before I laid out the money to buy it. However, I see a grid hybrid system more as insurance to protect my family and I from something that is less likely to happen. Such as rapidly rising energy costs, long and short term grid failure due to winter storms, tornados, hurricanes, cyber attacks against power utilities, even economic problems, both personal and public. Insurance and investment are two very different mindsets requiring different ways of considering money and resources. Those of us who buy grid hybrid systems want to have the convenience of grid power, while at the same time having the security of a well maintained off grid system available. So I am not adverse to paying a premium for this type of insurance.

Rick

[wgollie43]

Hi wgollie43,

Good, glad we are getting results.
Well, like I said, I don't know the range of voltages that reflect the usable capacity of your AGM's. I do know how the Radian running the GridZero app should work. I would say that if you moved the DoD volts set point from 50V to 49V and the inverter started then the GridZero app is responding to the battery capacity dropping below 100%. I recommend doing some testing. Record the voltage and battery capacity when the inverter cuts off. Then drop the DoD voltage setting again. Record the same again. Try tweaking it until the battery capacity reaches 70%, when the inverter shuts down. Testing will show you where the possible set points really are, whether it is 20, 25, or 30% DoD.
Also, how many KWH's per day average have you been producing since you had your system installed? This has to do with the DoD amps setting, but we'll get into that next time.

Rick

I talked to OutBack support and they told me that 50% DOD would be about 46Volts. For some reason that just does not make sense to me because that puts it below the 12 Volts for each battery. Also, I was told that the Radian GS4048A in GridZero mode will not pull from the batteries when the total amps is less than 1. That I can accept. I also need to check and see if I have data logging enabled. That may help me analyze the points you mentioned above. Also need to get a laptop connected to Mate3. When I get home this evening I will set my DOD Volts to 48.8.

[paulcheung]

Remember the voltage under load is different from open circuit. Rolls suggest 50% DOD under load is 46.32volts on 48 volt system. I set my at 47 volts. it hardly reach there but occasionally it went there if I have a cloudy day. so if you set it at 48.8 volts, you will use a lot of the grid power unless your system is grossly over sized.