Leave inverter on or off

[Radtech]

Looking at an all in one inverter the MPPS 1000w 12V hooked to 2 200w panels with 2 lifepo4 batteries. This will be installed at my off the grid cabin that we use on weekends in the summer and fall. Since the cabin is vacant during the week should I leave the inverter on or turn it off during this time? Thanks

 

[timselectric]

If the batteries are full and you won't need the power for anything, might as well shut it down.

 

[Bobert]

Looking at an all in one inverter the MPPS 1000w 12V hooked to 2 200w panels with 2 lifepo4 batteries. This will be installed at my off the grid cabin that we use on weekends in the summer and fall. Since the cabin is vacant during the week should I leave the inverter on or turn it off during this time? Thanks

The inverter will have an idle current draw sometimes an AIO will have as much as a 70 watts of power consumption when it is on. This number is unlikely with a unit as small as yours but you should be aware of that factor. My AIO will still charge the batteries from solar even if the inverter is off if that is the case with your AIO I see no reason to leave it on.

 

[Radtech]

If the inverter is off what keeps the batteries from overcharging?

 

[Radtech]

The inverter will have an idle current draw sometimes an AIO will have as much as a 70 watts of power consumption when it is on. This number is unlikely with a unit as small as yours but you should be aware of that factor. My AIO will still charge the batteries from solar even if the inverter is off if that is the case with your AIO I see no reason to leave it on.

What kind of AIO do you have. Are you run grid power through it as well. The MPP that I’m looking at I’m able to hook generator to and run through the AIO.

 

[Bobert]

What kind of AIO do you have. Are you run grid power through it as well. The MPP that I’m looking at I’m able to hook generator to and run through the AIO.

I have a powmr 3500watt single phase 110 unit. I have the input wired to the shore plug on my travel trailer I can connect grid or shore power to the plug. You should be aware if you have never used an AIO that they have limitations on how they can be used in conjunction with grid or solar. Technically the 3500 watt AIO I have needs a 40 amp grid connecton or around a 10000 watt generator in order to work properly. I discussed this a bit on another thread and included a video that explains these limitations. https://diysolarforum.com/threads/the-challenges-of-using-a-generator-on-an-all-in-one-system.34845/

 

[Bobert]

If the inverter is off what keeps the batteries from overcharging?

You set a charge profile that charges your batteries to the desired voltages wether you are on grid, solar or both

 

[MichaelK]

Nothing really has been mentioned about what loads you are planning on running? From your first post, I read that you haven't yet purchased the unit yet? I would dissuade you with going with the 12V MPP 1000 for two reasons. First, I would consider marginally small to begin with, and second, I am not a fan of 12V for anything that does not have wheels.

A cabin system will really start to shine at 24V, and automatically doubling the system voltage means you can double the wattage of your solar array. As system size increases, the background idle consumption gets less and less important. Since grid-tie panels are so cheap these days, idle consumption can be dealt better via just adding more watts of panels.

Spend a bit more time shopping, and you'll find other inverters that have significantly lower idle consumption, on the order of 20-30W total. One extra grid-tie panel is likely to totally offset that level of consumption.

24V will let you later easily incorporate larger appliances like a refrigerator or freezer, when you decide you need one, and the larger scale will more easily allow you to leave things on 24/7. What I see is that the best quality electronics start at 24V, so you would be well on your way starting there.

Four 250-260W panels is running ~65-75$ right now on Craigslist, so, for 300$ you can start to build a 24V system that significantly out-matches what you can do with those 200W panels.

 

[TomC4306]

My AIO will still charge the batteries from solar even if the inverter is off if that is the case with your AIO I see no reason to leave it on.

That^

 

[Radtech]

Nothing really has been mentioned about what loads you are planning on running? From your first post, I read that you haven't yet purchased the unit yet? I would dissuade you with going with the 12V MPP 1000 for two reasons. First, I would consider marginally small to begin with, and second, I am not a fan of 12V for anything that does not have wheels.

A cabin system will really start to shine at 24V, and automatically doubling the system voltage means you can double the wattage of your solar array. As system size increases, the background idle consumption gets less and less important. Since grid-tie panels are so cheap these days, idle consumption can be dealt better via just adding more watts of panels.

Spend a bit more time shopping, and you'll find other inverters that have significantly lower idle consumption, on the order of 20-30W total. One extra grid-tie panel is likely to totally offset that level of consumption.

24V will let you later easily incorporate larger appliances like a refrigerator or freezer, when you decide you need one, and the larger scale will more easily allow you to leave things on 24/7. What I see is that the best quality electronics start at 24V, so you would be well on your way starting there.

Four 250-260W panels is running ~65-75$ right now on Craigslist, so, for 300$ you can start to build a 24V system that significantly out-matches what you can do with those 200W panels.

Thanks for all the input. Really a newbie at all this. So far at my cabin all I have are led lights and a few outlets. Gas stove. No fridge. Not sure I really plan on running a fridge but who knows in the future.

 

[Bobert]

The inverter will have an idle current draw sometimes an AIO will have as much as a 70 watts of power consumption when it is on. This number is unlikely with a unit as small as yours but you should be aware of that factor. My AIO will still charge the batteries from solar even if the inverter is off if that is the case with your AIO I see no reason to leave it on.

By the way my AIO uses roughly 50 watts idle.

 

[MichaelK]

Thanks for all the input. Really a newbie at all this. So far at my cabin all I have are led lights and a few outlets. Gas stove. No fridge. Not sure I really plan on running a fridge but who knows in the future.

At my own cabin, I started out at 12V just like everyone else, and quickly get disappointed. Upgrade to 24V and I promise you that you will not be disappointed.

If there happens to be a 12VDC item you just can't give up, then one of these inexpensive 24V to 12V converters will work for you.

24V to 12V 20A DC DC Converter 20AMP 240 Watt Voltage Step Down Module | eBay

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[timselectric]

In my opinion there's only two choices in battery voltage. 12v for portable systems and 48v for permanent systems. Maybe 24v for a mobile application that already has a 24v starting system. Just for simplicity.

 

[MichaelK]

I started off with 1/2 ton pickup. Years later got 1 ton pickup. Currently I have a 2 ton and a 3/4 ton. Each met/meets a need, which has evolved over time. To suggest that there should only be two system voltages is like saying there should only be two standards of truck. Just silly.

Each size serves a specific purpose, and I currently run both 24 and 48V systems, both of which work splendedly. They work. Managing a solar system entails the proper understanding of scale. I wouldn't change anything. Base your decisions on results, not opinions.

 

[timselectric]

24v wouldn't exist, anymore. If it wasn't for the mobile market. But, everyone is welcome to use whatever they want. I can only make suggestions.

 

[Radtech]

I started off with 1/2 ton pickup. Years later got 1 ton pickup. Currently I have a 2 ton and a 3/4 ton. Each met/meets a need, which has evolved over time. To suggest that there should only be two system voltages is like saying there should only be two standards of truck. Just silly.

Each size serves a specific purpose, and I currently run both 24 and 48V systems, both of which work splendedly. They work. Managing a solar system entails the proper understanding of scale. I wouldn't change anything. Base your decisions on results, not opinions.

Excellent advice. Thanks