Beginner Build - Looking for Recommendation/Suggestions

[andrewh]

*originally posted this in "Newcomers" but moving in case that was the wrong place (can't figure out how to delete that one)*

Hello all,

I'm a beginner and would like to set up an off grid tiny home/cabin with solar power on an inverter/charger. Watched a few of Will's videos to get an idea of how to get things started and still learning a lot. The most I have done in the past is just set up and use of Goal Zero Yeti 1250 and, more recently, Bluetti's AC300 (after watching Will's video on that unit). Both of these systems are basically "plug and play" so not much research or setup involved.

Wanted to share my cabin power configuration on here to see if anyone could take a look and let me know if I am on the right track, if I might be missing something, any general recommendations, or if there might be any concerns with this setup. This is my first time doing anything like this, so any/all help is much appreciated.

The cabin will be used occasionally, someone may stay in there on and off for around a week at a time. The breaker box will be run to around 5 outlets and 3 lights (all 12/2 Romex inside). The purpose for the generator will be for occasional use of an electric stove and/or coffee maker, but also for charging the batteries if the weather turns cloudy for several days. A propane heater will be used in the winter, which does not connect to any power. The location is northern Arizona, so it stays sunny most of the year other than around July-September with monsoon season. The breaker box is oversized but we will only be using a couple breakers for two runs in the cabin. Anyone using the cabin will know not to use any high powered items without starting the generator first. As far as I can tell, this generator cannot be setup to auto start when batteries run low so a close eye will be kept on the charge levels and charged as needed (using Renogy 500A Battery Monitor with Shunt, High and Low Voltage Programmable Alarm).

Hopefully, I'm setting this up to be able to scale up in the future with additional solar panels and potentially use lithium batteries instead, but that might be quite some time out. The 6x Trojan T105 batteries that I am using were purchased for our RV but the originals are still going strong so I figured these could be setup to use in the cabin instead.

Please take a look at the below/attached configuration/notes and let me know your thoughts or if any other info might be helpful.

Thanks,
Andrew

 

[Samsonite801]

This is essentially the same system I helped a friend (on our co-op) build and set up on his little off-grid RV (back when I knew a lot less about solar stuff). We had used a 2500w AIMS inverter, but instead with 2x 405w panels and a Victron 150|70 charge controller. I don't really know anything about Renogy, but I really love Victron with the awesome bluetooth app control using Victron Connect app.


His system worked fine except after a few months his AIMS inverter stopped working. We called AIMS and we wound up having to freight it back to them at our expense but they replaced a bunch of boards in it with what they said were new and improved boards (for free), and shipped it back to us I think at their expense.

That inverter has been working fine for a couple years so far after that. At least I can say that AIMS was helpful in getting the unit repaired back then.

My main thing on panels is, just to get the highest wattage ones for the physical size you can get, and like always make sure you wire them so you don't go over on the max PV volts at lowest temperature compensated...

Looking back on retrospect, I would say that since then I have learned a lot more now. The thing I always say now is, if you really have in mind that you know you will expand the system later (want true scaleability), then just know that a system of this type has limited scaleability... You can add better batteries and some more charge controllers and solar panels, but if you add inverters, they would have to supply different AC circuits since the AIMS style inverters aren't parallel stackable (they can only service independent circuits).

Generally I say, that this type of system you're planning is fine if you don't really plan to scale it much. But if you want a system that can scale a lot smoother, I might buy based on a parallel stackable inverter and build off of that instead. Going to 48v battery bank voltage would also mean watts can go higher than 3000w (which is about the limit with 12v on a single inverter), and 48v, the battery cable sizes can be smaller.

I believe the 12v 3000w Victron Multiplus inverters can be parallel stacked and provide 6000w though, I've never tried it, just saw a You Tube video showing how to stack 2 of those (with a parallel comm cable). I do know the Victron Multiplus are good, since I have another friend who put one in his van-life Dodge Ram van and he likes it a lot.

 

[12VoltInstalls]

I also would suggest buying higher wattage panels. For two reasons.

1) running an electric stove takes a lot of power
2) 400W of 100W panels costs more per watt than much larger panels will.

The other thing is your inverter appears to be single phase 120VAC and a stove will want 240VAC.

 

[Bluedog225]

Use up what you have, including the batteries. Agreed on considering 48v.

Ditch the electric stove/coffee. Propane, kerosine, alcohol, wood are all a better source of heat in my opinion.

Start thinking in terms of how many watts you need. This will help al lot.

edit-and when it’s time, get some much bigger panels. E.g. 4x-400 watts. It’s nice to have some extra power.

 

[Samsonite801]

I also would suggest buying higher wattage panels. For two reasons.

1) running an electric stove takes a lot of power
2) 400W of 100W panels costs more per watt than much larger panels will.

The other thing is your inverter appears to be single phase 120VAC and a stove will want 240VAC.

Yeah and one thing I learned from real world use, is that 400w is really maybe like 375w on a good day, and when the clouds come it's like 50w if you're lucky. Always think of the watts rating as the best case scenario.

 

[andrewh]

Hello everyone, and thanks so much for the replies and all the info/recommendations. For the electric stove top, we are thinking of using a very small/portable stove for occasional use. Something like this from Home Depot (maybe not exactly, but just to give an idea) - 2-Burner 6 in. Stainless Steel Infrared Countertop Hot Plate (1800 W). Would something that small still need to have 24v? This would not be run on the batteries alone, the generator would be running through the inverter/charger for this type of higher powered item. We'll also look for an energy star coffee pot as we don't have a wood burning stove or gas running to the cabin, other than a propane tank directly to the heater.

The panels I picked up were from Amazon on Prime Day and seemed like quite a discount, probably around $0.75 per watt. I'm located quite a way from anywhere that I can physically pickup equipment so I end up getting most items delivered, ordered online. Is it true that the larger panels also use the same voltage as the smaller panels? The manufacturer of the 100w panels lists them as 12v. Would larger panels like the 400w panels also be 12v? Can 400w panels be used in a series/parallel setup with the smaller 100w panels? Might be a stupid question, but I would definitely do my best research prior to doing anything on this build.

His system worked fine except after a few months his AIMS inverter stopped working. We called AIMS and we wound up having to freight it back to them at our expense but they replaced a bunch of boards in it with what they said were new and improved boards (for free), and shipped it back to us I think at their expense.

That inverter has been working fine for a couple years so far after that. At least I can say that AIMS was helpful in getting the unit repaired back then.

The reviews for this inverter showed that that was a common issue and people were saying the cost to ship the unit back was quite expensive. I purchased the 3yr Amazon warranty, which I don't often do, since they showed as covering shipping to return the unit for repair. Hopefully this isn't a defective unit and, if it is, hopefully the warranty will be worth the purchase

 

[andrewh]

This build is using a lot of the info that Will had on his The Classic 400 Watt (RV's, Big Vans, Buses I understand this is not the exact same setup but tried to keep some things somewhat similar. He has the same charge controller and the same amperage circuit breaker.

I called Renogy, since that's the manufacturer for the charge controller and the a few other items, to ask them about the fuses in my configuration. They mentioned that I need to match the amp from the charge controller on the fuse between the charge controller and battery bank. Thinking about swapping the 50amp for a 40amp. They are also recommending a fuse instead of a circuit breaker.

Will didn't use the same inverter and the one he used may have been smaller. Renogy recommended that I call AIMS, the inverter manufacturer and ask their recommendation for the fuse between the inverter and the battery bank. Renogy did mention, based on the specs that I would probably need to use a 300A fuse instead of the 250A that I have.

Still need to research the different types of fuses and was mainly going with just what Will had (circuit breaker between charge controller and battery bank and the MEGA/AMG between the battery bank and inverter). Does the size circuit breaker and fuses that I am using in that build seem to be proper for these items? And does anyone recommend using a fuse instead of circuit breaker, and a different type of fuse between the battery bank and inverter, instead of the MEGA/AMG?

 

[SilverbackMP]

Hello everyone, and thanks so much for the replies and all the info/recommendations. For the electric stove top, we are thinking of using a very small/portable stove for occasional use. Something like this from Home Depot (maybe not exactly, but just to give an idea) - 2-Burner 6 in. Stainless Steel Infrared Countertop Hot Plate (1800 W). Would something that small still need to have 24v? This would not be run on the batteries alone, the generator would be running through the inverter/charger for this type of higher powered item. We'll also look for an energy star coffee pot as we don't have a wood burning stove or gas running to the cabin, other than a propane tank directly to the heater.

The panels I picked up were from Amazon on Prime Day and seemed like quite a discount, probably around $0.75 per watt. I'm located quite a way from anywhere that I can physically pickup equipment so I end up getting most items delivered, ordered online. Is it true that the larger panels also use the same voltage as the smaller panels? The manufacturer of the 100w panels lists them as 12v. Would larger panels like the 400w panels also be 12v? Can 400w panels be used in a series/parallel setup with the smaller 100w panels? Might be a stupid question, but I would definitely do my best research prior to doing anything on this build.



The reviews for this inverter showed that that was a common issue and people were saying the cost to ship the unit back was quite expensive. I purchased the 3yr Amazon warranty, which I don't often do, since they showed as covering shipping to return the unit for repair. Hopefully this isn't a defective unit and, if it is, hopefully the warranty will be worth the purchase

Almost no reason anyone should be using a hot plate these days. Solar or not.

Look into portable induction stoves. Only downside is you need carbon steel or cast iron pots and pans and/or stainless that are magnetic and/or pans with an applied ferrous coating (aka “induction ready”).

Or get a propane unit like a Camp Chef.

 

[Samsonite801]

The panels I picked up were from Amazon on Prime Day and seemed like quite a discount, probably around $0.75 per watt. I'm located quite a way from anywhere that I can physically pickup equipment so I end up getting most items delivered, ordered online. Is it true that the larger panels also use the same voltage as the smaller panels? The manufacturer of the 100w panels lists them as 12v. Would larger panels like the 400w panels also be 12v? Can 400w panels be used in a series/parallel setup with the smaller 100w panels? Might be a stupid question, but I would definitely do my best research prior to doing anything on this build.

There is really no such thing as a '12v' solar panel in reality. There is a Voc (Volts Open Circuit) rating, and you need to look at the sticker or specs sheet on the panel, because big panels they can easily have a Voc of 50+ volts. You don't want to go over Voc (and with cold temperature compensation) of your charge controller or you will fry it for sure. As the temps drop, the Voc goes higher according to the temperature coefficient spec on the sticker too, so need some extra leeway to account for that.

 

[Samsonite801]

Still need to research the different types of fuses and was mainly going with just what Will had (circuit breaker between charge controller and battery bank and the MEGA/AMG between the battery bank and inverter). Does the size circuit breaker and fuses that I am using in that build seem to be proper for these items? And does anyone recommend using a fuse instead of circuit breaker, and a different type of fuse between the battery bank and inverter, instead of the MEGA/AMG?

Fuses and breakers should all be sized to protect the wire, so first you figure out what the max amps is that the device will draw or flow on it's circuit at peak, then factor in voltage drop related to length, then the 80% rule, which is to size the breaker or fuse for 80% of the max allowed safe current flow of the cable, and this is the general basis for protecting the wire from having a meltdown.

For a large 12v inverter (2500-3000w), you should always use the largest cable 4/0 (4 aught), (which is NOT the same as 4 awg, 4/0 is much larger gauge).

On my 2800w Magnum inverter, I use a 350a amp Class-T fuse... I have 2 parallel runs of 2/0 cable feeding my fuseholder (it was convenient since I had a lot of that cable laying around, so I ran the 2 smaller cable runs there side-by-side), then I have a single 4/0 cable going from fuseholder to my inverter.

 

[12VoltInstalls]

energy star coffee pot

English translation: one pot of coffee every three light years.