Duh! They are not going to say that. If they told the truth, they would scare customers away and loose business.
Hybrid Ouback Skybox with Nissan Leaf batteries
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...... Most off grid and otherwise fit for purpose systems can be safely operated w/out an aux. generator but many/most experienced off grid users seem to feel a pressing need for them usually sooner rather than later, sometimes in short order based on experience.
Perhaps they know something you haven't discovered yet.
This is the Hybrid , Grid Tied With Batteries section of this forum correct? If I had wanted advice on an off grid system I would have posted in the off grid section of this forum.Last edited by Ampster; 11-23-2018, 09:13 AM.Leave a comment:
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As for peddlers, why would they have any interest in selling or creating a need for equipment they do not peddle that will only make an install more costly and also point out shortcomings in their product ?
Maybe the difference lies in the definition/context of "mandatory". I can sail/operate a boat without an anchor or spare sails, but those things come in handy. Most off grid and otherwise fit for purpose systems can be safely operated w/out an aux. generator but many/most experienced off grid users seem to feel a pressing need for them usually sooner rather than later, sometimes in short order based on experience.
Perhaps they know something you haven't discovered yet.
Many users on and off grid break their ass getting some types of rather sophisticated monitoring they seem to not be able to live without (or have been brainwashed into believing it's essential). To them, such information is "mandatory" even though they haven't a clue of the difference between a watt and a kWh much less what much if any of their monitored output means.
Definitions of conditions such as mandatory and essential are often more situation variable than preferences often more user specific and not as mandated as sometimes thought.Last edited by J.P.M.; 11-22-2018, 04:44 PM.Leave a comment:
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OK thanks. That makes it easier to give advice.
A few notes about that:
1) The Skybox has a single MPPT channel, unlike inverters like the SMA line which have multiple channels. So you have to be careful to match string lengths and orientations.
2) Incrementally adding storage can be a bit problematic, since batteries will typically share unequally. With lithium the problem is lessened, but you still won't get great sharing (i.e. some batteries will bottom out before others, currents won't go where you think they should.)
2) I am going to pay more attention to that before I add much more capacity. I don't have much quality control over any additional Leaf modules that I might add. I may have to do some sort of binning as I add modules to the pack. It will be 14 cells in series (7 modules).
No worries there. If you don't want to get a generator, don't get one. Just know that pretty much everyone who has tried to make a go of it off grid has wound up with a generator.
Also, a propane generator requires effectively zero maintenance or care if you never use it. And if you never use it - there's no noise. When the day comes that you really need it, you are better off trying to decide whether to make some noise or not than to not have that option.
You can't rely on charge current declining in an AC coupled system - because the battery will go overvoltage before the charge current declines.
You won't have a problem during normal operation. During AC coupled operation (i.e. power outages) you can't use charge current to terminate. You need to use SoC.
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Lead acid batteries do not use BMSes so no communication will be required. You can tell the inverter you have a lead acid battery, then set absorb and float voltages to the same value (i.e. 4.1 or 4.2 volts per cell) and the li-ions will be happy with that.
Other batteries do use BMSes. So if you set the inverter to (for example) "LG RESU10" it will look for that CAN bus communication. (There are a lot more protocols/interfaces than just CAN out there.) That's why you might have to tell it you have a lead acid battery. Or you may be able to tell it you have something like a SimpliPhi battery, since those do not have externally accessible coms either.
Last edited by Ampster; 11-21-2018, 10:26 PM.Leave a comment:
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I have had a deposit on a Tesla Powerwall fo a year and no delivery date is in sight. After rebates and tax credits the Powerwall was going to cost $4,000. It would have allowed me to reach my goals cost effectively but I am tired of waiting. My Skybox project will give me several additional advantages over the Powerwall. With the Skybox I can incrementally add solar. I can also incrementally add more battery capacity at $200/kWh.
1) The Skybox has a single MPPT channel, unlike inverters like the SMA line which have multiple channels. So you have to be careful to match string lengths and orientations.
2) Incrementally adding storage can be a bit problematic, since batteries will typically share unequally. With lithium the problem is lessened, but you still won't get great sharing (i.e. some batteries will bottom out before others, currents won't go where you think they should.)
I completely understand why an off grid system would have a generator. When the sun doesn't shine there is no power. In a grid tie system when the grid is down there is a high probability that there is sunshine. I also don't want a generator making noise and taking up space. I don't want to maintain the generator and store the fuel to keep it running. I can think of many other reasons that I don't want a generator. The concept is free will.
Also, a propane generator requires effectively zero maintenance or care if you never use it. And if you never use it - there's no noise. When the day comes that you really need it, you are better off trying to decide whether to make some noise or not than to not have that option.
@jflory2, if you really want to help, tell me how to break up a quote on this forum so I can interlineate my answers like you do.
Are you defining full power as 1C? Then the answer is no I do not want to charge at full power. Initially I will not have solar on this inverter. I will be charging from the grid or loosely AC coupled to my grid tie inverter. I will choose when I charge and I will choose how much power I charge at based on my battery capacity. I have a dream that by nursing my battery pack, I can get 8 years out of it.
You won't have a problem during normal operation. During AC coupled operation (i.e. power outages) you can't use charge current to terminate. You need to use SoC.
It can measure current on the ports. I don't know of it uses a shunt, hall effect sensor or a CT. You may be wrong. RTFM
I assume what you mean is a BMS that can be programmed. I am using an Orion Jr which I have left over from another project. It can only shunt a small current but I am less concerned about balancing currents. I want to adjust the parameters to send alarms as well as monitor and control charging.
I am not sure I understand to which device your example of spoofing applies. I don't know why I would tell either of those devices that I was using lead acid. Are you familiar with the Orion?
Also please explain what you mean when you say, "per Outback the way it's supposed to be used is with a battery that can communicate with the Skybox." Are you talking about CAN bus communication. That is an area where I could use some help from someone knowledgeable with the CAN bus communication. I used contact closures and relays to control my previous Radian system.
Other batteries do use BMSes. So if you set the inverter to (for example) "LG RESU10" it will look for that CAN bus communication. (There are a lot more protocols/interfaces than just CAN out there.) That's why you might have to tell it you have a lead acid battery. Or you may be able to tell it you have something like a SimpliPhi battery, since those do not have externally accessible coms either.Leave a comment:
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Model year was 2014, I bought them in 2016 and they were at roughly 90% rated capacity. Today, two years later at 75% capacity and ready to be replaced. Once the batteries hit the magic 80% capacity the ride to to 0 is very fast. So if it takes say 4 years to 80%, you have less than a year until unusable if you are lucky. Sort of like when you turn 55 to 60 years old, you slow down, and then aging accelerates very quickly.
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I completely understand why an off grid system would have a generator. When the sun doesn't shine there is no power. In a grid tie system when the grid is down there is a high probability that there is sunshine. I also don't want a generator making noise and taking up space. I don't want to maintain the generator and store the fuel to keep it running.
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The battery has to have the right BMS to be able to communicate with the Skybox. I have no doubt you could spoof it by telling it (for example) that it's a lead acid battery or something, but per Outback the way it's supposed to be used is with a battery that can communicate with the Skybox.
The chemistry itself doesn't matter. The fact that lithium chemistries need BMSes is what matters. If people had sodium-sulfur batteries that needed a BMS the same comment would apply.
I am not sure I understand to which device your example of spoofing applies. I don't know why I would tell either of those devices that I was using lead acid. Are you familiar with the Orion?
Also please explain what you mean when you say, "per Outback the way it's supposed to be used is with a battery that can communicate with the Skybox." Are you talking about CAN bus communication. That is an area where I could use some help from someone knowledgeable with the CAN bus communication. I used contact closures and relays to control my previous Radian system.Last edited by Ampster; 11-21-2018, 01:24 PM.Leave a comment:
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Are you defining full power as 1C? Then the answer is no I do not want to charge at full power. Initially I will not have solar on this inverter. I will be charging from the grid or loosely AC coupled to my grid tie inverter. I will choose when I charge and I will choose how much power I charge at based on my battery capacity. I have a dream that by nursing my battery pack, I can get 8 years out of it.Leave a comment:
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Right. So your payback time has to include regular battery replacements.
Agreed. But:
1) is a money issue. This system will not save you money due to battery cost.
2) and 3) are for backup power and your needs will be better served by a generator. (That's why pretty much every off-grid system has a generator; it's the reliable backup for the less reliable solar system.)
I have a feeling that you just really, really want to build a solar battery system, even if it isn't cost effective. If so, that's fine - it's your money. But let's state that up front.............
I have had a deposit on a Tesla Powerwall fo a year and no delivery date is in sight. After rebates and tax credits the Powerwall was going to cost $4,000. It would have allowed me to reach my goals cost effectively but I am tired of waiting. My Skybox project will give me several additional advantages over the Powerwall. With the Skybox I can incrementally add solar. I can also incrementally add more battery capacity at $200/kWh.
I completely understand why an off grid system would have a generator. When the sun doesn't shine there is no power. In a grid tie system when the grid is down there is a high probability that there is sunshine. I also don't want a generator making noise and taking up space. I don't want to maintain the generator and store the fuel to keep it running. I can think of many other reasons that I don't want a generator. The concept is free will.
@jflory2, if you really want to help, tell me how to break up a quote on this forum so I can interlineate my answers like you do.Leave a comment:
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