Our off grid cabin Victron/Trophy setup

[Nan_wpg]

Right, it makes sense to bond the DC system to ground. So I want to know why (and which) battery manufacturer says to not do so, and under which circumstances.

I mean electricity is electricity. Ohms laws aren’t suggestions. It’s either required or it’s not??

 

[AHTrimble]

Sorry I had you confused with Barthold. Do you have any postings about your system?

your bank is a trophy battery currently grounded (bonded)?

if (for example) Victron says to bond battery, and battery says not to who do you believe?

Yeah, gonna do a before/after thread on it, it's not up yet.
I have 2 Elites (48v,205ah) currently, will add a 3rd (Trophy, 48v, 220ah).
I will do what the battery company says.

 

[Rocksnsalt]

Hi All,

Here’s my setup for our off grid cabin that we recently completed. Goal was to have enough battery and solar to basically (almost) never have to run the generator. The cabin consumes more electricity in the winter than the summer, due to having to run the furnace, and of course there’s less solar hours in the winter. On an average winter day, we consume 12 to 17 KWh. With the setup below, I can run 5 to 6 days before the generator will have to kick in, which is plenty of time. It hardly ever is cloudy for that long in a row over here.

The cabin has only one 220V load, and that is the well pump (about 11A @ 220V). In the future there will be an electric vehicle 20A or 30A 230V outlet as well.

I started out with Full River AGM batteries and an Outback inverter/mppt/mate system, but I didn’t like either enough to keep them. The long tail to get the AGM batteries fully charged is a waste of solar hours, and the (pretty extreme) capacity degradation in the cold, plus the fact that to get the optimal amount of cycles you should not discharge to about 60% SOC, made the AGMs less than ideal. The outback system simply isn’t as cool or flexible as a Victron setup, so that had to go as well.

So this is the setup:

• Five Trophy 304Ah lithium batteries, for a total of 1520 Ah @ 51V, or about 77 KWh. Love those batteries!
• Victron MultiPlus-II 48/10000/140-100/100 inverter (230V model)
• Victron 100A Autotransformer to feed a standard electrical panel for my 110V needs
• Victron Smartsolar MPPT RS 450/200
• Victron CerboGX with GX Tank 140 (super cool! I can monitor the amount of drinking water in my 3000 gallon cistern that way)
  • Relay 1 of the CerboGX is used to control the well pump, when the water level in the cistern is getting low
• Two Victron BMV 712 battery monitors. One is hooked up to the CerboGX to provide SOC, and battery temp. The other is just there so I can ALSO see the SOC in the cabin, on the display of the BMV 712.
  • Whenever I get the Trophy batteries to talk to the CerboGX, one of them can go. Working with Dan @ Trophy on making this happen, but so far no luck.
  • The main BMV 712 is also used to start the generator on a low SOC of the batteries. I couldn’t use the CerboGX for this, as the relay on the CerboGX controls the well pump.
• 11 Silfab 490 solar panels. These things are amazing, Although officially rated at 490W, I have drawn 670 Watts per panel out of an array of six of these panels. Being at 9300 foot altitude, and a nice sunny cold winter day, gets the best out of them. I put them in a string of 5 and a string of 6 panels, and use two out of the four MPPT controllers in the Victron MPPT RS (so far).
• Midnite solar MNE250STSLT E panel, which is used to house a 250A breaker for the inverter feed, and a 175A breaker for the MPPT controller feed.
• Flowline Echopod UG-6 acoustic water level sensor to measure the water in the cistern
• Some odds and ends like the well pump protector, well pump remote controller, generator on/off/auto switch, and temperature monitor and heater inside the batter box.

Pictures below.

Be happy to answer any questions!

Barthold

The full setup in one picture.
View attachment 127281

The five Trophy 304Ah batteries, with an interesting wiring setup as per Trophy's recommendation. I built an insulated box around the batteries, as it does get cold here. The box is two layers of R13 rigid foam, for a total of R26. There's also a lid with the same insulation (not shown).
View attachment 127282

Midnite solar panel with 250A breaker to the inverter on the left, and the 175A solar controller breaker on the right. The top breakers are not used.
View attachment 127283

Four of the 11 panels on one pole. Rest not shown.
View attachment 127284

Looking down into the cistern where you can see the Flowline Echopod measuring water level. The cistern is about 300 foot away from the Victron GX Tank 140. Works like a charm!
View attachment 127285

Screenshot of Victron VRM in action. This was a cloudy day, not a lot of solar produced.
View attachment 127286

Nice system. ????
What type of rigid foam and thickness are you using to get R26 ?
And are you including the plywood in your R value?
Thanks


PS Love ? the warning sticker! Custom made or available somewhere online?

 

[Nan_wpg]

Nice system. ????
What type of rigid foam and thickness are you using to get R26 ?
And are you including the plywood in your R value?
Thanks


PS Love ? the warning sticker! Custom made or available somewhere online?

If you look up AVE on YouTube he has links in his videos for the stickers. He sells them on etscy. He’s got a bunch of different stickers. His Chanel is a hoot to watch as well.

 

[Horsefly]

What type of rigid foam and thickness are you using to get R26 ?
And are you including the plywood in your R value?

When I was building my insulated battery box, I ended up using 2" XPS, which had an R value of 10. Normal 2" rigid foam board was only R of 7.7. 3/4" plywood has an R value of close to 1.0, I think. So I'm not sure how he gets to 26, but with two layers of plywood (can't tell how thick), I could see it being R22 (10+10+1+1), which is close.

 

[Rocksnsalt]

When I was building my insulated battery box, I ended up using 2" XPS, which had an R value of 10. Normal 2" rigid foam board was only R of 7.7. 3/4" plywood has an R value of close to 1.0, I think. So I'm not sure how he gets to 26, but with two layers of plywood (can't tell how thick), I could see it being R22 (10+10+1+1), which is close.

Yes your R10 XPS and plywood example is exactly what I came up with but the walls don’t appear to be 4” of foam which is why I’m wondering how to get to R26. I have a couple attic walls I’d love to get R26 on but that should require at least 5.125” of XPS foam.
The battery box walls appear to be (2) 2“ foam + (2) .5“ plywood walls so 5” total including plywood, which would be around R21.
Still, great insulation for a battery box and a nice system.

 

[CTS]

Awesome setup! I am looking at getting a very similar setup brand wise, but will be a much smaller scale for our off grid cabin. What kind of temp are you getting to in the winter? We get some extreme cold here in Manitoba and wonder how well these Lithium batteries will work out.

You also have me reconsidering my original idea of going with a 120v system and thinking I should go the 240v with autotransformer route. I will have to read up on that article you posted.

One question I have is how loud are these inverter/chargers/autotransformer? Could they be mounted in a cabin or should they be mounted in a separate shed on the property?

I will be referencing this thread a lot in the coming year!

 

[barthold]

When I was building my insulated battery box, I ended up using 2" XPS, which had an R value of 10. Normal 2" rigid foam board was only R of 7.7. 3/4" plywood has an R value of close to 1.0, I think. So I'm not sure how he gets to 26, but with two layers of plywood (can't tell how thick), I could see it being R22 (10+10+1+1), which is close.

Hi everyone,

The insides are 4" of rigid foam, and then the plywood on both sides. I also insulated the bottom of the box the same way, so it is insulated on six sides. The foam I used claims to be a R value of 6.5 per inch, here it is:

https://www.lowes.com/pd/Johns-Manville-Common-2-in-x-4-ft-x-8-ft-Actual-2-in-x-4-ft-x-8-ft-AP-Foil-1-R-13-Faced-Polyisocyanurate-Foam-Board-Insulation/3851107

Regardless of the actual R value, the box works great. The little pad heaters I stuck on the side of the batteries have ran maybe 10 hours total this winter, and I keep the temperature at 50F inside the box. So I'm super happy with it.

 

[barthold]

Awesome setup! I am looking at getting a very similar setup brand wise, but will be a much smaller scale for our off grid cabin. What kind of temp are you getting to in the winter? We get some extreme cold here in Manitoba and wonder how well these Lithium batteries will work out.

You also have me reconsidering my original idea of going with a 120v system and thinking I should go the 240v with autotransformer route. I will have to read up on that article you posted.

One question I have is how loud are these inverter/chargers/autotransformer? Could they be mounted in a cabin or should they be mounted in a separate shed on the property?

I will be referencing this thread a lot in the coming year!

Hi CTS,

It can get below zero Farenheit here in the winter, and it has. My shed with all the equipment in it has south facing windows, so it does warm up nicely during the day if it is sunny out (and we get a lot of sun in the winter). The shed is a log shed, with an insulated roof. But no heater. You must keep your lithium batteries warm!

At low loads the fans don't run, but once you start drawing a load they do come on. They all have fans. So if you were to put it inside, I would put it in a closet with a well closing door, but then if you do that you need to worry about the closet heating up too much. So maybe best to just put it in an outside building if you can, or garage.

 

[Rocksnsalt]

Hi everyone,

The insides are 4" of rigid foam, and then the plywood on both sides. I also insulated the bottom of the box the same way, so it is insulated on six sides. The foam I used claims to be a R value of 6.5 per inch, here it is:

https://www.lowes.com/pd/Johns-Manville-Common-2-in-x-4-ft-x-8-ft-Actual-2-in-x-4-ft-x-8-ft-AP-Foil-1-R-13-Faced-Polyisocyanurate-Foam-Board-Insulation/3851107

Regardless of the actual R value, the box works great. The little pad heaters I stuck on the side of the batteries have ran maybe 10 hours total this winter, and I keep the temperature at 50F inside the box. So I'm super happy with it.

The only thing that truly matters is that it works for you and your use case, regardless of R value.

Having researched foam board insulation performance a while back, I was surprised to discover that unlike XPS and EPS, Poly iso foam actually loses significant R value in cold temps. I discovered this after poly iso’ing the inside of an exterior garage wall of my place that does see night temps in the 20F range regularly in winter, with a few single digit nights here and there.

Cold-Weather Performance of Polyisocyanurate - GreenBuildingAdvisor

The ability of insulation products to resist the flow of heat changes with temperature. Most insulation products — including fiberglass batts, extruded polystyrene (XPS), and expanded polystyrene (EPS) — perform better at low temperatures than high temperatures. At lower temperatures, there is...

www.greenbuildingadvisor.com

http://www.owenscorning.com/NetworkShare/EIS/10019949-FOAMULAR-XPS-vs-Polyiso-Tech-Bulletin.pdf

Again, awesome system and glad everything is working well.

 

[Horsefly]

Hi everyone,

The insides are 4" of rigid foam, and then the plywood on both sides. I also insulated the bottom of the box the same way, so it is insulated on six sides. The foam I used claims to be a R value of 6.5 per inch, here it is:

https://www.lowes.com/pd/Johns-Manville-Common-2-in-x-4-ft-x-8-ft-Actual-2-in-x-4-ft-x-8-ft-AP-Foil-1-R-13-Faced-Polyisocyanurate-Foam-Board-Insulation/3851107

Regardless of the actual R value, the box works great. The little pad heaters I stuck on the side of the batteries have ran maybe 10 hours total this winter, and I keep the temperature at 50F inside the box. So I'm super happy with it.

Well, that explains it then. You have R26 not even counting the plywood. I hadn't seen this type of foam board. Well done. I might have used this kind of foam board instead of the XPS to get more insulation, but to be honest the XPS seems to do well for my box.

 

[Rocksnsalt]

Well, that explains it then. You have R26 not even counting the plywood. I hadn't seen this type of foam board. Well done. I might have used this kind of foam board instead of the XPS to get more insulation, but to be honest the XPS seems to do well for my box.

You may find the articles linked in post 70 of interest. If you used XPS foam for a cold climate, you did well. Wish I had.

 

[Horsefly]

You may find the articles linked in post 70 of interest. If you used XPS foam for a cold climate, you did well. Wish I had.

Oh! I missed that. I guess I'm happy that I used XPS.

 

[featherlite]

XPS insulation like Owens Corning and Johns Mansfield have a maximum service temperature of 165 degrees F, whereas the Polyiso has a maximum service temperature of 600 degrees F.

When I insulated my aluminum cargo trailer, I wanted to use the XPS but chose the Polyiso because, in direct sun, the temperature of the skin and roof of my trailer far exceeds 165 degrees F.

However, for keeping a battery warm in cold temperatures, the XPS makes more sense to me.

 

[Rocksnsalt]

XPS insulation like Owens Corning and Johns Mansfield have a maximum service temperature of 165 degrees F, whereas the Polyiso has a maximum service temperature of 600 degrees F.

When I insulated my aluminum cargo trailer, I wanted to use the XPS but chose the Polyiso because, in direct sun, the temperature of the skin and roof of my trailer far exceeds 165 degrees F.

However, for keeping a battery warm in cold temperatures, the XPS makes more sense to me.

It’s my understanding all these foams degrade with age and high temps, I believe “thermal drift” is the term.

I’m planning on using foam to insulate a future battery bank in my Sprinter van, and the walls and ceiling of a recently acquired 12x7x6.5ft (stationary) storage trailer.
Which foam board will work best is debatebke, as the ambient temps range from occasional (F) single digits to 105+. The latter of which being why I chose a bright white trailer.
I’m planning on covering the roof of the trailer with 1000-1200W (maybe bi facial?) of solar panels, but may have to sacrifice some space for a roof vent fan as well.

 

[barthold]

Having researched foam board insulation performance a while back, I was surprised to discover that unlike XPS and EPS, Poly iso foam actually loses significant R value in cold temps. I discovered this after poly iso’ing the inside of an exterior garage wall of my place that does see night temps in the 20F range regularly in winter, with a few single digit nights here and there.

oh, I didn't know that! Thanks for the links!