3R Home and Barn Project

[Mrs3RRL]

After reading some of the manuals and correspondence your solar guy wrote, I question his real knowledge, my guess is he knows about half of what he is doing. What makes me think that way is the fact he is adding acid to the batteries, that is a big no no, as Mopacman (Larry) wrote, you only add distilled water to batteries, never acid - if he (the solar guy) is adding acid to the batteries it will further destroy them. Also, some of the "Techno babble" he wrote trying to answer some of your questions made absolutely no sense at all, another reason I am suspicious of him. Perhaps a second opinion from a qualified solar technician is in order.

I totally agree. I, too, believe he only knows helf of what he's doing, and the other part he's guessing at or researching on the fly.

However, trying to find a 'qualified solar technician' is harder than it may seem. There is a local solar installation company I contacted when I first began to suspect that our installer was less than competent in some areas, and we were having problems. This guy came out, looked at the system, basically shook his head, said it was 'really hard to figure out a system that someone else put together', and ended up not doing nothing and charging us nothing.

 

[denmansoft]

The most important thing I've found in my battery systems is the batteries and cells all need to be matched pretty closely. if one is weak in a series string the others will overcharge and the total looks good. One bad cell and the whole string drops down to a 'discharged state' after say 5% usage because thats all the charge in that one cell.

I am not familiar with the electronics and inverters you are using, but I would go and measure (and log on paper) each battery voltage. Do this every couple of days for a week or so and you will see any problem batteries. They should all read the same voltage +/- 1-2%. If your battery bank is not stable and balanced you will never get close to rated power usage.

 

[GuglioLS]

Aside from getting 8 huge 48v batteries, obviously ($$$) I am interested in getting the 16 we have now working to the best of their capability. How can we do that? Is "A single series string" the answer? What can we do to balance the resistance? Any way to check that?

If I understand correctly there are 16 12V batteries (two separate banks of eight wired such to get 48 volts, is that assumption correct? Or are they 6 volt batteries? in other words two completely separate banks of batts with one set of eight going to the shop / barn and the other bank of eight going to the home? If that is correct then the reserve capacity is split 50% home 50% shop. Or are all 16 somehow tied together? I also wonder how the solar panels are wired - one giant system or two separate ones? Normally it's not good practice to wire batteries in parallel due to different rates at which they charge or discharge. That difference is caused by slight variations of internal resistance or charge. This is especially true when they sit idle, one battery tends to have slightly more voltage that slowly discharges into another with slightly lower voltage. If say you wanted all the reserve capacity of all 16 battery's available to the home and shop then those two banks could theoretical be wired in parallel. The key to getting the resistance equal would be to have the exact same length and gauge of cables connecting the two banks together. In theory that should balance the banks of batteries to output power and receive a charge in equal proportions. However doing it that way does not account for internal differences between any battery wired in parallel. That is the very reason a single string of batteries in series is almost always the best option. No doubt the system can get complicated and choices / compromises have to be made. I guess the trick is finding the right configuration to match your situation.

Can the inverters be configured to accept 96 volts as opposed to 48 volts? (all the batteries could be wired in one big series string) If that were the case it could be a better situation as the amperage being carried by the cables would be reduce by half as would any voltage drop, the system would be much more efficient configured that way. On the down side, 96 volts DC represents a serious shock hazard. I believe the danger threshold in right at 50 volts. Maybe that's why the system is 48 volts? It may not be possible, but maybe worth investigating. I wish I had the technical manuals for those outbacks and the mates - sounds Australian, is that were they are manufactured? I wish I could be of more help, If we knew the exact way the system is wired now and knew all the variable ways of how it could be wired, more helpful and specific advice could be given.

I wish you the best of luck with that solar installer dude! maybe he got shocked one too many times like me?
.
Larry

 

[Mrs3RRL]

If I understand correctly there are 16 12V batteries (two separate banks of eight wired such to get 48 volts, is that assumption correct? Or are they 6 volt batteries? in other words two completely separate banks of batts with one set of eight going to the shop / barn and the other bank of eight going to the home?

The battery banks themselves are not split between house and barn. It is basically one battery bank (so to speak), in terms of what goes to the inverters.

There are 4 banks of batteries, with 4 batteries each. My understanding is that these are connected in parallel and series. In other words, 4 batteries in each series, and then the 4 series are parallel.

There are 2 MX-60 charge controllers that charge the overall battery bank - one for each solar array.

So, the energy accumulation and storage isn't split.

At the inverters, though, is where the systems split. At that point, there are 4 inverters (one master nad 3 slaves) for the house and 2 (one master and one slave) for the barn.

The generator is only connected to the 4 inverters for the house. So, the generator is triggered by the master inverter for the house. When the generator runs, it goes through the battery chargers that are in the house inverters. The barn inverters don't get any generator current directly, but get it solely from the batteries.

 

[Mrs3RRL]

I wish I had the technical manuals for those outbacks and the mates - sounds Australian, is that were they are manufactured? I wish I could be of more help, If we knew the exact way the system is wired now and knew all the variable ways of how it could be wired, more helpful and specific advice could be given.Larry

Ask, and ye shall receive:

OutBack Power / Resources / Documents

OutBack Power / Resources / Tech Notes

http://outbackpower.com/products/sinewave_inverter/off_grid/

 

[RavensRoost]

Loretta, there are some folks over on that solar forum that are solar installers/contractors who very much seem to know what they are doing. Heck, I bet some are even in California, perhaps even in your area.

There is also the guy known as "Crewzer" (Jim) on the solar forum that I view to be the most knowledgeable person I have ever read on any solar forum, and somewhere in the past several months began working for Outback so his expertise is free. He also seems to be a genuinely nice guy, so I would ask him to review the high level design and strategy options with pro/con for you from an Outback perspective. (He sort of got into doing that when you were posting about problems, but appears to have gotten distracted as I do not recall reading his analysis, but I may have missed it.) Y

ou may also want a solar contractor to look at all of the nuts and bolts -- especially all inverter/MX60/Mate setpoints -- and trades stuff and give you a second opinion on that portion, but I suspect you would have to pay a consultancy fee.

You have a large investment in your solar system and will be depending on it for some time to come...and it is an enabler to enjoying your chosen dream retirement location. Even if you have to pay, I would have someone else review everything your solar guy has done.

My earlier comments about single strings of batteries is really closing the barn door after the horses are gone. If ever you need to change out the battery plant, be looking for a way to get it to a single (series) string or two strings max while still getting all the Amp Hours you need.

Meanwhile, as someone else mentioned, you can help the situation by ensuring the electrical cables between the batteries and inverters and MX60s are at opposite "corners". To visualize what I am saying, draw 4 rectangles end to end to represent the 4x12v batteries in one series string, then add 3 more strings alongside it to represent your plant. At each end all 4 strings are cabled together for the parallel part -- positive is at one end and negative the other -- so if the positive cable happens to connect say in the top left corner, then the negative should be in the bottom right.

I have always thought it would be wise to rotate this electrical relationship periodically, but have not seen anything supporting my notion. (I do have 3 series strings of 4 each 6v batts in my system and put a heavy copper buss bar at each end to facilitate doing this...but have not yet played.)

Regards,
RavensRoost

 

[charlz]

I totally agree. I, too, believe he only knows helf of what he's doing, and the other part he's guessing at or researching on the fly.

However, trying to find a 'qualified solar technician' is harder than it may seem. There is a local solar installation company I contacted when I first began to suspect that our installer was less than competent in some areas, and we were having problems. This guy came out, looked at the system, basically shook his head, said it was 'really hard to figure out a system that someone else put together', and ended up not doing nothing and charging us nothing.

So out of curiosity, have you, or will you be presented with an 'as built' schematic for the system? If this guy gets hit by a bus tomorrow it sounds like you would be out of luck for having someone else figure it out.

 

[Mrs3RRL]

Loretta, there are some folks over on that solar forum that are solar installers/contractors who very much seem to know what they are doing. Heck, I bet some are even in California, perhaps even in your area.
There is also the guy known as "Crewzer" (Jim) on the solar forum that I view to be the most knowledgeable person I have ever read on any solar forum, and somewhere in the past several months began working for Outback so his expertise is free. He also seems to be a genuinely nice guy, so I would ask him to review the high level design and strategy options with pro/con for you from an Outback perspective. (He sort of got into doing that when you were posting about problems, but appears to have gotten distracted as I do not recall reading his analysis, but I may have missed it.)

Thanks for the encouragement, Bruce. As you can see from this forum as well, I haven't had any time to even check the forums lately. Jim did give some very detailed information and is obviously very knowledgeable. This is all so foreign to me, that I struggle to understand it, and I have to really sit down and think about it. With everything else that's going on, it's hard to find time to do that. Then, even when I think I sort of understand it, it's hard for me to ... well, 'stand up' to our solar guy and get him to agree to change it. Even if he did change it, if it didn't work because of some other reason, I would imagine that he would then say it was all my 'fault'. I really do want him 'on the hook', so to speak, to make it run right.

You may also want a solar contractor to look at all of the nuts and bolts -- especially all inverter/MX60/Mate setpoints -- and trades stuff and give you a second opinion on that portion, but I suspect you would have to pay a consultancy fee.

Well, that's what I had thought I was doing when I called the local solar company - the one where the guy came out and had never worked with Outback products and couldn't figure it out. I remember when I was first researching who to hire to do this, that there is some kind of certification, so maybe I'll go to that website and see if there's someone in our area who is certified.

The way we got hooked up with him in the first place is that I called a relatively local company, and they told me that they primarily do on-grid, but that they sub-contract with this guy for their off-grid.

Even if you have to pay, I would have someone else review everything your solar guy has done.

You have a very good point.

Meanwhile, as someone else mentioned, you can help the situation by ensuring the electrical cables between the batteries and inverters and MX60s are at opposite "corners". To visualize what I am saying, draw 4 rectangles end to end to represent the 4x12v batteries in one series string, then add 3 more strings alongside it to represent your plant. At each end all 4 strings are cabled together for the parallel part -- positive is at one end and negative the other -- so if the positive cable happens to connect say in the top left corner, then the negative should be in the bottom right.

I believe that's what he recently did as one of his changes. Rob understands that part better than I do, but I think there's a copper buss bar that was supposed to accomplish this, but he moved the wiring to be more direct... or something like that. But I recall him talking about it, and in my little pea brain, it was sort of like connecting the furthest diagonal points.

 

[Mrs3RRL]

So out of curiosity, have you, or will you be presented with an 'as built' schematic for the system? If this guy gets hit by a bus tomorrow it sounds like you would be out of luck for having someone else figure it out.

Well, he did provide us with a 'book' that included what were supposedly the schematics. But, when I took a close look at them, they appeared to be just the schematics from the installation manuals.

I discovered this when, in an effort to understand it all, I created my own diagram of how I thought everything fit together. I based it on his diagrams and information from the Outback documentation, then I sent it to him for review. That's when he commented about some of the things that were different in how things were actually hooked up.

Also, I know that sometimes he thought he had something hooked up a certain way, and it turned out he didn't.... or didn't have it correct (for instance the master/slave relationships and the ports for the MATE). So even if he gave us what he thinks is the correct schematic, it doesn't mean that's what it actually is.

Having said that, I'm going to try again to get him to do that. At least I'll know what he thinks he's trying to do. Honestly, we feel pretty much 'at his mercy'... and sometimes that feels like having heart surgery done by a doctor that's actually a cosmetician.

 

[charlz]

Also, I know that sometimes he thought he had something hooked up a certain way, and it turned out he didn't.... or didn't have it correct (for instance the master/slave relationships and the ports for the MATE). So even if he gave us what he thinks is the correct schematic, it doesn't mean that's what it actually is.

Having said that, I'm going to try again to get him to do that. At least I'll know what he thinks he's trying to do. Honestly, we feel pretty much 'at his mercy'... and sometimes that feels like having heart surgery done by a doctor that's actually a cosmetician.

Yep that's the purpose in the 'as built'... you have the 'theory' and then you have 'the plan' and then you have the 'as built' which is how it was actually put together. The 'as built' is critical for him, you and anyone else to understand the system. Sounds even more critical here as it sounds like he more or less skipped 'the plan' stage.