System Review

NaughtGeek

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Oct 7, 2021
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I've spent a bunch of time reading and planning and the attached is what I've come up with. It would be great if y'all might look over my sketch and let me know if I'm missing anything critical. I'm a little fuzzy on PV disconnects. Are they only required if the inverters are on the panels? If I need one for this setup, any suggestions on something that will work for the array I have sketched out? If it's not clear from the sketch, I have the AC and DC separate. I've already purchased the LV6548s and the EVE cells as well as a Batrium BMS. I believe I will be going to get the panels in the next week or 2 but I'm still trying to figure out a cost effective way to mount them. My intention is to gradually move my loads from the main panel and power them from the sub panel but I need to reduce consumption which is going to require monitoring and planning. Current monthly usage peaks around 2600KWh. I'm hoping to replace HVAC with multi zone mini split which should help, the electric stove and hot water are going to be a hurdle.

SystemSketch.PNG
 
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FilterGuy

What, me worry?
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Los Gatos CA
I've spent a bunch of time reading and planning and the attached is what I've come up with. It would be great if y'all might look over my sketch and let me know if I'm missing anything critical. I'm a little fuzzy on PV disconnects. Are they only required if the inverters are on the panels? If I need one for this setup, any suggestions on something that will work for the array I have sketched out? If it's not clear from the sketch, I have the AC and DC separate. I've already purchased the LV6548s and the EVE cells as well as a Batrium BMS. I believe I will be going to get the panels in the next week or 2 but I'm still trying to figure out a cost effective way to mount them. My intention is to gradually move my loads from the main panel and power them from the sub panel but I need to reduce consumption which is going to require monitoring and planning. Current monthly usage peaks around 2600KWh. I'm hoping to replace HVAC with multi zone mini split which should help, the electric stove and hot water are going to be a hurdle.
View attachment 68208
A couple things jump out at me.

1) the 150A breakers seem too small for the LV6548.
Assume a 95% efficiency on the inverter. Then the inverter could draw 6500W/.95=6842W. If the battery is low, that means the draw on the battery could be 6842/48=142A. The fuse or breaker should be 25% larger than the max sustained current. 142 x 1.25=178A. You might have to round that up to 180 or maybe even 200A depending on the type/brand fuse or breaker used.

2) The fusing on the panels is wrong. If there are more than 2 panels in parallel, there needs to be a fuse on each panel.

Where you show the fuse/breaker on solar, will need a disconnect. The disconnect should be on both the positive and negative PV leads.
 

NaughtGeek

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Oct 7, 2021
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Thanks for the reply @FilterGuy , I drew the panels out wrong. They will be in series. I've been looking at this too long and my brain fizzled out on that one. Also, I have to admit I got lazy on the 150A breaker and didn't do the math myself, I just used what Will used in his setup. I've spent the last several hours trying to find a suitable 1000A buss bar setup as the 300A bus bars he used certainly won't work in my system. Looking at the Victron LYNX distribution modules but haven't sorted that all the way out. Now off to redraw the array. Thanks again :)
 

FilterGuy

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Thanks for the reply @FilterGuy , I drew the panels out wrong. They will be in series.
I wondered why they were in parallel... but figured you had your reasons. :)

Now that I think about it, I realize they would not even work in parallel. The voltage would be too low for a 48V battery.
 

FilterGuy

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BTW: I have no idea what the usage profile is, but the size of the battery bank seems small compared to the rest of the system.

If each of the inverters were running at 50% load, it would be 13000W. At 95% efficiency that is 356A.
With 304Ah cells, that is only 51 minutes.
 

NaughtGeek

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Oct 7, 2021
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You are correct sir, I need a lot more battery. Starting with one bank while I monitor and move loads and will scale up later. Trying to shed load first so I don't have to buy more batteries/panels than I need. My dream would be to shed enough load that I could drop 2 of the LV6548s but I don't know that I can shed that much. Drawing has been updated to show panels in series and the disconnects. Trying to find disconnects with as many poles as possible but looks like I'm going to need several :-(
 

FilterGuy

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My intention is to gradually move my loads from the main panel and power them from the sub panel but I need to reduce consumption which is going to require monitoring and planning.
Have you considered one of the whole-house power monitors?

the electric stove and hot water are going to be a hurdle.
Stove:
* Take a look at inductive ranges. I have heard they are a lot more efficient.
* Is LP or Natural gas an option?

Hot Water:
* Folks on the forum have talked about heat-pump water heaters being very efficient.
* Are on-demand heaters a possibility? It will have a very large short-term draw but much lower total energy usage.
* Is LP or Natural gas an option?
 

NaughtGeek

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@FilterGuy , gas isn't an option for me as I'm doing all this with the aim of self sufficiency. I haven't looked at the whole home monitors. This started as hurricane prep with extended power outage in mind and keeping a deep freezer and fridge running and has spiraled out from there. First loads to go on the sub panel will be freezer and fridge. If I can get the funds together, a multi zone mini split will likely be next. I did look at the Rheem heat pump water heaters but I don't see getting the funds together for that in the short term. My range is getting raggedy so I'll put an eye to induction ranges. Thanks for the suggestion.

@robby , it's Excel

@smoothJoey , thank you sir ;-)
 
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