Mixing systems vs staying with single manufacturer

[David Collins]

New member, designing an off grid system for a weekend use cabin. Questions on what unforeseen issues I might be faced with when mixing systems rather than staying within one manufacturer.

The constant I’m committed to is 12 SunTech 275w 24v roof mounted panels. 2.5-5kWh battery capacity will be suitable, and we do not plan on running more than a single 120vac 20a circuit. My priorities are -

#1 - Safety. This is an off grid occasional weekend use cabin in the middle of Michigan woods, and a fire could in a worst case scenario mean dozens of acres ablaze before anyone noticed. And the system will be inside the cabin. I can handle all the proper gauging, calculations, fire protection, fuses and switches, crimps and connections, but need reliable components as well, with lowest history/risk of internal failures.

#2 - Noise. I want as silent a system as possible, with no fans running unless we’re actually drawing enough current to warrant it. Fans running while we are using a vacuum or coffee pot is inevitable, but I’d like to avoid fans on the charge controller, or when we’re running 50 watts of lightbulbs.

#3 - Low Maintenance. After initial setup, I would like to monitor, maintain, or even think about the system as little as absolutely possible.

#4 - Cost. I’ll pay for quality, but do not have an unlimited budget, and want to get the best value within the constraints of priorities 1-3.

My dilemma is that the Eg4 LiFePower batteries seem too good to pass up, ($1500 for 5kwh 48v, compared to $1030 for an SOK 2.5kWh 24v), but the Eg4 3000k All In One appears to fail my noise priorities from what I’ve heard. Therefore I’m considering a fan-less Victron 250/60 charge controller, and probably a Xijia 3000w pure sine inverter (the Victron batteries and inverters are a bit high for my budget), which seems to have a good design for not running the fans more than it needs. This combination will cost more and be a more complicated setup than using the Eg4 3000w all in one, but is worth it to me for the noise factor.

My question then is, am I shooting myself in the foot on priority #4 (low maintenance, good self regulation) by choosing a charger, inverter, and BMS which cannot communicate with each other? What will such an arrangement be missing, and what vulnerabilities for problems or increased maintenance might this expose me to?

Thank you in advance for any insights, warnings, tips, or alternatives you may have to offer.

 

[Steve_S]

You say 120V/20A is what you think you will pull.
That is ONE 120V Circuit with a maximum allowable 10 devices (plugs/switches)
That requires 2400W *Uncorrected

A 2000W Inverter or Inverter/Charger will not deliver that, you'll have to look at the 3000W and up devices.
* A Combined Inverter & Charger is more costly at first blush but cheaper if you have to buy both an Inverter & separate Charger.
* An AIO (All In One) which combines Solar, Inverter, Charger into one box may "seem" attractive due to cost but running overhead is higher and it is either ON or OFF and that's all of it. If there is no need for AC Power when away then the inverter should be off (saving power). Note that there is a huge variety of AIO's with differing functions.

12V/24V/48V ?
For this setup more than 24V is NOT needed, 3000W @ 12V is pushing it a tad too far.

I would seriously look at the Victron 24V Family: When put into ECO Mode, they use very little power which is fine for when you are away.

MultiPlus-II 3000VA - 5000VA - 8000VA - 10000VA - 15000VA
EasySolar-II GX 3000VA, 5000VA
EasySolar 1600VA, 3000VA, 5000VA

The Victron integration is excellent and remote monitoring is possible with it all, even several LFP Battery Packs can interact with their hardware which is a big bonus as well.

I am a 24V Based Offgridder. Things to keep in mind, a coffee maker pulls 50A from 24V while brewing, my Panasonic 1200W Inverter Microwave pulls 74A, 4HP Shop Vac pulls 42A+/-. Light Bulbs: LED For cripes Sake, no incandescent stuff !

Batteries: Being Michigan you get cold down there (I'm in Northern Canada so you are down there) and LFP cannot be charged below 32F. Any Battery Pack(s) will require warming capability as you are not in residence. You can buy Prebuilt or DIY these and it depends on the depth of your pockets (and marriage stability, hehehe) EG4, SOK, PylonTech are good prebuilts See link here:

Server Rack LiFePO4 Solar Batteries

High quality, high capacity solar batteries at a great price! These are taking over the market because they have everything. State of charge indicator, communication system, high quality BMS and a...

www.mobile-solarpower.com

24V/100AH/2560Wh is "light" IMO. You'd want at least 200AH and you can add more in parallel later if required.

Solar Panel Mounting: BIGGY ! Again because you are not resident, you need a steep enough angle for the snow to shed, so if you have a 12/12 Pitch roof (45 degrees) facing Due South you'd be generally OK, or a ground mount with at least 4' of clearance from panel to grade will also do, as the snow has to have somewhere to fall and not cover panels.

Hope it helps, Good Luck.

 

[David Collins]

You say 120V/20A is what you think you will pull.
That is ONE 120V Circuit with a maximum allowable 10 devices (plugs/switches)
That requires 2400W *Uncorrected

A 2000W Inverter or Inverter/Charger will not deliver that, you'll have to look at the 3000W and up devices.
* A Combined Inverter & Charger is more costly at first blush but cheaper if you have to buy both an Inverter & separate Charger.
* An AIO (All In One) which combines Solar, Inverter, Charger into one box may "seem" attractive due to cost but running overhead is higher and it is either ON or OFF and that's all of it. If there is no need for AC Power when away then the inverter should be off (saving power). Note that there is a huge variety of AIO's with differing functions.

12V/24V/48V ?
For this setup more than 24V is NOT needed, 3000W @ 12V is pushing it a tad too far.

I would seriously look at the Victron 24V Family: When put into ECO Mode, they use very little power which is fine for when you are away.

MultiPlus-II 3000VA - 5000VA - 8000VA - 10000VA - 15000VA
EasySolar-II GX 3000VA, 5000VA
EasySolar 1600VA, 3000VA, 5000VA

The Victron integration is excellent and remote monitoring is possible with it all, even several LFP Battery Packs can interact with their hardware which is a big bonus as well.

I am a 24V Based Offgridder. Things to keep in mind, a coffee maker pulls 50A from 24V while brewing, my Panasonic 1200W Inverter Microwave pulls 74A, 4HP Shop Vac pulls 42A+/-. Light Bulbs: LED For cripes Sake, no incandescent stuff !

Batteries: Being Michigan you get cold down there (I'm in Northern Canada so you are down there) and LFP cannot be charged below 32F. Any Battery Pack(s) will require warming capability as you are not in residence. You can buy Prebuilt or DIY these and it depends on the depth of your pockets (and marriage stability, hehehe) EG4, SOK, PylonTech are good prebuilts See link here:

Server Rack LiFePO4 Solar Batteries

High quality, high capacity solar batteries at a great price! These are taking over the market because they have everything. State of charge indicator, communication system, high quality BMS and a...

www.mobile-solarpower.com

24V/100AH/2560Wh is "light" IMO. You'd want at least 200AH and you can add more in parallel later if required.

Solar Panel Mounting: BIGGY ! Again because you are not resident, you need a steep enough angle for the snow to shed, so if you have a 12/12 Pitch roof (45 degrees) facing Due South you'd be generally OK, or a ground mount with at least 4' of clearance from panel to grade will also do, as the snow has to have somewhere to fall and not cover panels.

Hope it helps, Good Luck.

Thanks for the response and feedback.

I will be using a 3000w inverter, not 2000. Even though I expect to rarely see more than 100w load on the system up front, for times we want to do a cleaning or run power tools for updates, I’d like to be able to pull up to 2400watts on occasion.

This is a hunting cabin with a wood stove, hand pump well, outhouse, propane refrigerator and lights, so initially I will be drawing little more than some LED lights we’ll install, charging my laptop as I check trail cam cards, and maybe run a fan in the summer. I’m trying to build with expansion in mind - we’re considering digging for a septic and adding a bathroom, which would also mean dropping a submersible 1hp pump down our well pipe (it’s shallow), and maybe replace the propane fridge with a mini electric. So anything over 1000w of use right now will be limited to vacuuming a few times a year, or charging drill batteries and plugging in the occasional circular saw when doing improvements.

Part of my thought of going to 48v was simply cost and compatibility with upgrades. If I’m using SOK or Eg4 batteries, the cost per kWh is the same as 12 or 24, but if I want to switch to a different charge/inverter system, it seems like 48v offers us much more choices as we expand. Plus, if I use a Victron MPPT to start with, a 250/70 would allow up to full use of the panels for charging a 48v, while at 24v I would need to charge at over 110amps to store the same energy. This is why for battery choice I thought the Eg4 48v 100ah made the most sense. Cheapest per ah, long life, easy to expand if we find the need, and compatible with the widest range of future upgrades.

I will likely be shutting the system down entirely for winter. We can only access the cabin by snowshoeing in a half mile most of the time, so for now I’ll be shutting it down, and if I need to I can clear snow with a pole brush and start it up in the rare case I need it. It’s a shallow angle roof and there is literally nowhere else the panels could go without clearing a lot of trees, so that’s what we’ll have to deal with.

My main concern though, is are there any issues with the Victron controller not being able to communicate with the Eg4 BMS? I can put a Victron Smart Battery Sense on the Eg4, but is that good enough communication of battery state to the controller to protect the battery’s health?

I really wish there was more broad standardization and compatibility between products. I see no good reason the Eg4 should not be able to communicate basic battery info back to the controller, other than short sighted proprietary protections.