This off grid project, what have I gotten myself into?

[Stormsoul]

I thought I did good research for higher DC voltage for longer run from back to the front of house. The inverter idle, and one less PV input and low freq that I probably didnt really need is causing second guessing.

 

[MrM1]

I thought I did good research for higher DC voltage for longer run from back to the front of house. The inverter idle, and one less PV input and low freq that I probably didnt really need is causing second guessing.

if your issue with the LVX 6048 is that it is Low Frequency, in that department you really cannot go wrong. It's not going to hurt you. Now I realize the LVX 6048 also does not shine in the idle consumption, but really, how often will you be idle anyway. When the sun is out, especially if you over panel to the point that you have too much, your idle draw will be off set in the day. And really inverters get more efficient to a point the larger the load put on them. So I do not think those issues are that much of a deal breaker. Unless you are using this inverter for an off grid cabin where it sits idle for several days or weeks it will be ok. For daily use it will be fine

If you rethink it and start over (return stuff etc) I would seriously consider 1 or 2 (if needed) Schneider XW pro + inverters, a pair (or more) of the Midnite Solar Classics, and a Midnite Solar ePanel. The XW has an idle current of 25ish watts, is low frequency, will start a "tank" and This combo would be bomb proof and handle anything you throw at it.

 

[Zwy]

I thought I did good research for higher DC voltage for longer run from back to the front of house. The inverter idle, and one less PV input and low freq that I probably didnt really need is causing second guessing.

You can always add additional SCC's, you don't need PV to run thru the inverter MPPT.

 

[Stormsoul]

Thank you MrM1, I don't really want to sent them back. I am looking for software to draw out my off grid system. any good free software recommendations. I found a few free ones with google. Just wanted to see what the forums use.

 

[BMcL]

You seem to have close to the same system as Will does; you can follow how he wired his system :

He has 3 videos on this setup and he covers updates as well.

 

[MrM1]

Thank you MrM1, I don't really want to sent them back. I am looking for software to draw out my off grid system. any good free software recommendations. I found a few free ones with google. Just wanted to see what the forums use.

Oddly I do my drawings in an old version of Microsoft office publisher. But I've been using desk top publishing programs since the early 90s, so they are easy for me.

Here is my latest project concoctions.

 

[FilterGuy]

Oddly I do my drawings in an old version of Microsoft office publisher.

Not so odd...... I just use Microsoft Powerpoint. Google Slides is a free equivalent.

If I were needing to simulate the circuits or send them off for PC board fabrication I would use a proper circuit design package. However, for posting on the forum, Powerpoint is easy, fast, and in some ways produces better results.

 

[Zwy]

Thank you MrM1, I don't really want to sent them back. I am looking for software to draw out my off grid system. any good free software recommendations. I found a few free ones with google. Just wanted to see what the forums use.

Best diagram I've seen was the one in this post. https://diysolarforum.com/threads/mpp-lv6548-ac-wiring-question.28655/post-344268

Note the manual transfer switch, you won't need it off grid but if you want a generator, might be wise to wire it up like that. Then when you run the generator, you have the choice to leave LV6048's on to charge batteries or run entirely off generator. Also, this allows your cabin or house to remain powered up when you work on your system.

 

[justgary]

Silly question: You are sizing your system to include your 19 and 21 year old "power hogs." How long will they be hogging your power?

Even if they plan to live in your basement forever, your wallet will appreciate weaning the hogs off of the power teat. Have you looked at reasonable ways to save power?

 

[Zwy]

Silly question: You are sizing your system to include your 19 and 21 year old "power hogs." How long will they be hogging your power?

Even if they plan to live in your basement forever, your wallet will appreciate weaning the hogs off of the power teat. Have you looked at reasonable ways to save power?

I didn't quite understand your post at first, went back to original posts. Yes, I wouldn't size the system according to their current needs, it's money wasted down the road. Either that or charge them rent...........

 

[Petergriffin]

8S on PV with 3 strings? 9S will get you over the 450V max PV input on cold mornings. You might be able to squeak by with 8S with 2 strings on one LVX6048, max PV amps is 20A. However that will put you over the 6000 watt PV input rating. 16x400=6400w

I don't recommend going over the rated PV input wattage per unit. I think you would be better served with another SCC on one string.



You really need an idea of how much power your household uses in a day. I use a Eyedro from Amazon to monitor our usage. https://eyedro.com/


2 things, one, you may not have enough battery reserve if your household usage is high, the low freq inverter you have chosen will have about 120w idle usage per unit and those watts need to be sourced from somewhere. During the day, PV covers it but at night you can use 240w x 10 to 12 hours which comes to 2.4Kw to 2.9Kw Second, the Overkill is a great BMS, but you are limited to 100a thru it. You might look into a BMS that can handle much higher amperage. Batrium and others are better choices for larger inverters. You have a low freq inverter with high surge ability but those watts come from your batteries thru the BMS.

Hello, Just going through my own Hell with this LVX 6048, You mentioned the MAX PV Amperage is 20 amp? for this unit? Literature says 27 AMP. Is this known to be true? For Max input PV current.

 

[Zwy]

Hello, Just going through my own Hell with this LVX 6048, You mentioned the MAX PV Amperage is 20 amp? for this unit? Literature says 27 AMP. Is this known to be true? For Max input PV current.

The max amps I refer to is the 2 strings in a 8S configuration. The panels are 9.89A, two strings in parallel would be 20A. The LVX6048 was rated at 6000W max PV input. With an 8S configuration using 49.1VOC panels, the VOC of the 2 parallel strings would be just under 400V with the panels he was using.

6000W max divided by the 400VOC gives us 15A max. With 2 strings in parallel, it would be just under 20A which is 6400W. So it would be 400W over. We know that peak PV output may or may not occur depending on many factors. The question becomes will an extra 400W possibly cause failure over time? Will the SCC just clip the amp input? I don't know, I do know the manufacturer states a max PV input of 6000W for a reason. I also know electronics run at the max input and output will generate more heat and over time the electronics will probably suffer shortened lifespan due to the heat.

Adding an external separate SCC is not hard or expensive. That is my recommendation for a similar situation rather than running the inverter SCC to the limits.

 

[SniperX]

Thank you FilterGuy, I know the inverters are over doing it, I wanted to pad there. I will put together a schematic of what I am planning, I do plan on another 32 cells. and at all times the battery packs will be close to the inverters. Good point on maybe not leaving them under the patio. I just need to consider summer heat in the garage. I can utilize a small window ac to keep it in range but that's more watts out the window. Ok thanks again all. FilterGuy can you elaborate on needing 263A over what would be on the bus from the batteries (200). I will add more batteries later.

Also, you may have vermin and such messing with those wires at night. They will be short-lived but still..

 

[SniperX]

Oddly I do my drawings in an old version of Microsoft office publisher. But I've been using desk top publishing programs since the early 90s, so they are easy for me.

Here is my latest project concoctions.

View attachment 81331

This is why I read and read even though most of it is over my head. I have literally been begging for a diagram just to be sure what I have planned is correct and here you post today. THANK YOU!!!

 

[Stormsoul]

I really should update this thread as I have learned a lot since the original post. I have everything installed and spent a fair bit of time going through inverter settings and learning from mistakes. For me as my seplos battery mason kits (2) are both C (CANN) bms's I am letting the default settings there control what I have to set the inverters to..i.e. meaning high is a little under bms cuttoff and low volt is a little above bms cutoff. Other settings are user for the battery (had to for settings adjustments), opt 10 to OSO as a test for a month as I don't want to place shift grid power to the battery and just run the battery, I want the sun to charge the battery and that setting (opt 5 I believe) is set to solar charge battery first before load. one last setting off the top of my head is opt 2 is SBU.

As far as future work, I need to try that solar monitor software with the raspberry pi. I need to read more on it to see if I can set that up with what I have and the type of bms I have. I need to install a breaker between T fuses and inverter for easy disconnect when I loose mpp settings or they change randomly and I need to reboot and re -program. Yeah that's a thing with non tier 1. I should post some pics but I need to clean up cables a little (and replace batt to bus bar wires that came with seplos with some big boy wires..they get a little warm).