Man This solar thing drive me nuts. help

[inetdog]

I do not know a whole lot. Just some conversations I have had with an Tech Rep and an Engineer I have become friends with over there.

I am a little bit surprised it has taken this long and only one company venturing into it. Power management has been around a long time in Telecom, Utilities, and home automation. We use it a lot in Telecom and Data centers to mange battery plants and energy cost. You see a little bit of it in grid tied systems like Enphase as an example. But that is more Bells and Whistles rather than active control.

It turns out that Midnite has been discussing quite a bit in their own forum and website.
I am as surprised as you are that such an "obvious" positive step has taken so long.

The other approach to dealing with battery current is clearly the fully-integrated system approach like the one Xantrex/Schneider is now taking, in which the CC, the Inverter(s) and hybrid Inverter/Charger all share their own current information so that the system master can sort out what the battery current is indirectly. But even that fails if you have DC loads in the system.
Truly, capturing the battery shunt information is the way to go.

One of the neat things about the WhizBang Jr. is that it uses only ground/CC negative to the shunt and a single additional wire to read out the shunt information at the Classic.

[Sunking]

One of the neat things about the WhizBang Jr. is that it uses only ground/CC negative to the shunt and a single additional wire to read out the shunt information at the Classic.

Not sure that is a good idea. Yeah I am sure, that is not a good idea as it forces you to run a grounded system. Non Referenced (grounded) systems have a lot of advantages like less prone to outages and safer. However there are limitations as to what you can run non referenced most notable 50 volt or less voltages aka low power and Midnite Solar product line is not tailored to low power markets. As for me though I prefer to pick which polarity to reference, and when the manufacture chooses for you eliminates that option.

[inetdog]

Not sure that is a good idea. Yeah I am sure, that is not a good idea as it forces you to run a grounded system. Non Referenced (grounded) systems have a lot of advantages like less prone to outages and safer. However there are limitations as to what you can run non referenced most notable 50 volt or less voltages aka low power and Midnite Solar product line is not tailored to low power markets. As for me though I prefer to pick which polarity to reference, and when the manufacture chooses for you eliminates that option.

There you go, insisting on actually designing things again. Why not just throw things together?

[paulcheung]

Two reasons.

1. Mainly the two systems are not the same power, so they cannot be the same current.
2. You do not have the sync cable installed to allow them to communicate.

Paul nothing is wrong, the system is doing what it is suppose to. The problem is you do not understand the system is not capable of doing what you want, and is under sized. Really not much more we can do for you. If you do not have a generator I suggest you get a battery charger to get the batteries charged up and quit using them.

The Outback send back a response that I should do a Vbattery calibration and I did, hope that will help.

I do have a desiel 3000 watts generator, and the inverter come with a battery charging circuit that I can use either the generator or the grid to charge the batteries. I don't really use the batteries to power the house again only to help when the cloud passing.

[Naptown]

For the life of me I cannot understand why you are using a battery system daily when you have grid power at the house.
The wear and tear on the batteries alone are costing you much more than what the grid power will cost.
Your best bet would to dump that inverter. Install something like a Xantrex XW series and net meter it.
Your savings will be higher without the inefficiencies of battery charging and your batteries will last a substantially longer time.

[Sunking]

For the life of me I cannot understand why you are using a battery system daily when you have grid power at the house.
The wear and tear on the batteries alone are costing you much more than what the grid power will cost.

I have been pounding that in him for 2 months. He does not want to hear it. I can only assume he likes throwing money away and has more than he knows what to do with. It would be better spent giving it to a church or food bank.

[paulcheung]

I have been pounding that in him for 2 months. He does not want to hear it. I can only assume he likes throwing money away and has more than he knows what to do with. It would be better spent giving it to a church or food bank.

Ok, Can you tell me how is grid tie work? do it still use batteries?
Say the house is using 2500watt and the solar is supplying 1500watt. what is going to happen. the inverter take 1000 watt from the grid to help the solar? or the inverter cut off the solar and use the grid entirely?

Thank you.

[SunEagle]

Ok, Can you tell me how is grid tie work? do it still use batteries?
Say the house is using 2500watt and the solar is supplying 1500watt. what is going to happen. the inverter take 1000 watt from the grid to help the solar? or the inverter cut off the solar and use the grid entirely?

Thank you.

A grid tie system works with the Utility and does not require any batteries. If your system is providing 1500 watts and you need 2500 watts, then the 1000 watt balance comes from the grid.

If your system is producing 1500 watts and you only need 1000 watts then your system sends 500 watts to the grid. Depending on the Utility you will get paid anywhere between 0% and 100% for each watt going to the grid. The best is called Net Metering where you would get paid 100% of what you generate to the grid.

The majority of the time your system will help reduce the amount of electricity you are purchasing from the grid. The lower the $/kWh cost of that electricity, the longer the payback will take to pay for your system.

[Sunking]

A grid tie system works with the Utility and does not require any batteries. If your system is providing 1500 watts and you need 2500 watts, then the 1000 watt balance comes from the grid.

If your system is producing 1500 watts and you only need 1000 watts then your system sends 500 watts to the grid. Depending on the Utility you will get paid anywhere between 0% and 100% for each watt going to the grid. The best is called Net Metering where you would get paid 100% of what you generate to the grid.

The majority of the time your system will help reduce the amount of electricity you are purchasing from the grid. The lower the $/kWh cost of that electricity, the longer the payback will take to pay for your system.

He is in Jamaica and Grid Tie is illegal.

[SunEagle]

He is in Jamaica and Grid Tie is illegal.

Snap. I missed that bit of info. Oh well. Just trying to help.

[Naptown]

Snap. I missed that bit of info. Oh well. Just trying to help.

Even so the Xantrex XW can be programmed to not export.

[paulcheung]

Things are changing in Jamaica. The grovenment has passed a law that solar systems are imported duty free and I think they also did some changes in the grid tie business. I am not sure if we can do net metering but I think grid tie is possible as long as I get a permit from the electricity company. well I have the batteries already. so I try to utilise them till they dead then I think about the grid tie. my system already work like grid tie. when the load is larger than the sun arrays it took the power from the battery to help and when the battery drop to such voltage it will shut down the inverting and take the power from the grid. when battery voltage rise to the preset amount it start inverting again.

Can some one tell me what is the correct voltage for the rolls batteries at 20% DOD underload?

Thank you.

[inetdog]

Can some one tell me what is the correct voltage for the rolls batteries at 20% DOD underload?

Thank you.

It depends entirely on the load. You can find very approximate tables for the relation between 100% SOC voltage and various DOD voltages with varying amounts of charge or discharge current (relative to the battery bank size).
But none of them will match your batteries exactly. You can use them to get a rough idea and then measure for yourself by looking at the voltage, current, and SOC from hydrometer measurement.
Not good enough to accurately predict SOC, but good enough to use to program the voltage limits on your inverter, etc.

[paulcheung]

I don't really need exact 20% DOD just about from 20 to 40% so it won't killed the batteries too quick. right now it set at 47volt under c/8 discharge load. I might have to put it to atleast 47.5volt.

Thank you.

PS. Just get the information from other thread, so I will set it at 48 volt and see how it work.
Thanks

[Sunking]

I don't really need exact 20% DOD just about from 20 to 40% so it won't killed the batteries too quick. right now it set at 47volt under c/8 discharge load.

That would be roughly 40 to 50% SOC meaning you have discharged 50 to 60% DoD. You are killing the batteries. 48.22 is your mark loaded