Six Panel Solar Setup - Couple of Questions

[speculant]

Complete beginner here but I have done some limited research and I want to make sure I don't make any huge mistakes. I'm trying to keep this project budget-friendly so I have sourced everything used and I have managed to keep it under $1000 so far. The primary goal of the project is to provide enough power to run 2 oscillating fans and a window fan basically 24/7 to help keep the air circulated so that is why I kept the inverter relatively small. The secondary goal is to provide a DC power source to charge other portable battery banks (Ecoflow, etc) which I use quite often in other areas of the house (I will save a lot of money if I can charge them via solar and not wall power).

I already installed six Trinasolar TSM-235PA05 panels in my backyard in a ground-mount south facing configuration. Per panel: VOC 37.1V, ISC 8.31A, PMAX 235W. I already have a Victron 150/60 MPPT charge controller and a 12V 300Ah Lifepo4 battery, and a 12V 400W pure sine inverter. I am waiting on receiving a Victron smart shunt so I can monitor SOC. I am planning on connecting the panels in a 3S2P config which should give me a VOC of 111.3V and ISC of 16.62A so the solar to the MPPT should be fine with 12AWG cables.

It appears that I will need a 30A fuse before the solar hits the MPPT (16.62 * 1.56 = 25.9 rounded up to 30). Do I also need a fuse between any other portions of the setup, and if so, how do I calculate the required size?

Also, I need some help in finding an appropriate solution for getting the solar cables into the house. This system won't be grid tied. I was looking at something like this. I would cut a 1-gang size hole on the inside wall for a low voltage bracket, drill through to the outside, mount the outside MC4 box to the siding (using long screws and caulk to seal it) and feed the 12AWG cables through a faceplate like this. The 30A solar fuse, MPPT, battery, and inverter will be inside of a cabinet with holes/fans for airflow that is secured to the wall so there wouldn't be any risk of anyone yanking the cables coming into the house from the exterior MC4 connectors.

Does this idea for getting the solar cables into the house sound appropriate for the size of the setup or is there any significantly better/safer way of doing it? Please let me know if there are any other suggestions or questions as well.

 

[seneysolar]

I typically use a Midnite baby box with their dc breakers for pv in (30a) and charge controller out (60a) to the batteries.

You will also need a fuse between the battery and inverter. With a small inverter like yours, it will depend on wire size but something like 8awg wire with a 30 or 40a fuse would be sufficient.

Fo going through a wall, you will want to use metal conduit with a junction box at each end. Dont use that plate you linked, thats just a decorative switch cover.

 

[speculant]

I typically use a Midnite baby box with their dc breakers for pv in (30a) and charge controller out (60a) to the batteries.

You will also need a fuse between the battery and inverter. With a small inverter like yours, it will depend on wire size but something like 8awg wire with a 30 or 40a fuse would be sufficient.

Fo going through a wall, you will want to use metal conduit with a junction box at each end. Dont use that plate you linked, thats just a decorative switch cover.

Ok that is great info. Is there any reason the solar fuse has to be on the outside of the house or is it fine to have it on the inside? I have seen some DIY video guides that show how to install junction boxes on each end through a wall with a threaded pipe so I think I can manage that just fine. What kind of connection on either end of the junction boxes is common to connect the solar panel wires into the house and then into the fuse/mppt? I’d rather not run the solar wires straight through from the inside to the outside, I’d like to have some kind of option to manually disconnect everything without having bare wires hanging out of either junction box.

 

[seneysolar]

Its a good idea to have a pv disconnect outside. I have seen them right at the solar array or right on the side of house before entry.
I really like the Midnite MNPV3 combiner box for that, its an outdoor rated box and the breakers can be used for disconnect. Its also easy to transition conduit with these. Im probably going to blow your budget with all the Midnite products

Otherwise, a quick search for pv disconnect brings up a bunch of options, but i have heard some of the plastic ones are garbage and have melted down in use.

 

[speculant]

Its a good idea to have a pv disconnect outside. I have seen them right at the solar array or right on the side of house before entry.
I really like the Midnite MNPV3 combiner box for that, its an outdoor rated box and the breakers can be used for disconnect. Its also easy to transition conduit with these. Im probably going to blow your budget with all the Midnite products

Otherwise, a quick search for pv disconnect brings up a bunch of options, but i have heard some of the plastic ones are garbage and have melted down in use.

Thank you for the great advice. I may or may not go with Midnite products in specific due to the cost but that is definitely pointing me in the right direction. I will either mount the PV disconnect/breakers at the last panel's mount closest to the house or on the exterior of the house depending on the type of exterior-rated metal junction box I can find that is in my budget. I'll stay away from the plastic ones that are clearly meant more for RV use.

 

[speculant]

I just want to say thank you again for the help! I ran the conduit, got the rest of the equipment installed, and today was the first day I’m making power! It was cloudy out but I still pulled 1.16kWh from the six panels. I don’t have a smart shunt yet but I think I’ll just wait on that as I won’t be pulling more than 1kWh from the system per day anyways so given today was very cloudy, I should be able to keep the battery topped off. I didn’t realize the Victron MPPT shows me a graph of how often the battery is going into float voltage which will give me a good enough indicator for now as to the battery’s charge at the end of each day since the load will be more or less constant.