Small Solar System for Mountains

[Nikg736]

I see the 3048 says it is parallel able and split phase able. I'm still learning, but it appears split phase is kind of like putting things in series. But unlike DC series connections that simply double the voltage, the split phase arrangement also puts the two 120v legs out of phase with each other just like grid power. If anything I think the 3048 would be the way to go. If project goes no further than the basics, I'm covered without adding extra cost. If something is in the cards further down the line, then the system can be expanded for 240v.

One more question...it seems that these particular MPP units' "zero transfer time" work because the inverter is always running to power the load. It's not really a "smart switch" from grid to battery with regards to handling the load. I think the only "switch" it makes is charging the bank from grid to charging the bank from solar. I'm not sure if I like that for a few reasons.
-First, if grid is up then it charges the battery bank and solar sits unused. The only time solar comes into play is when grid is down, so for this application it's so rare that it seems kind of pointless to add those panels. Just get more battery to fill in for the solar and cut down on the complexity of adding panels that basically won't be used. Is this correct? Is this how this thing works?
-Second, wouldn't that constant use wear out an inverter a lot faster than necessary? I'm no electrical wizard, but in my general experience when an electrical component runs 24/7 for 365 days a year vs maybe 2-5 times per year for 6-24 hours per occurrence, it wears out faster. Does that also mean this is constantly cycling the batteries and running the charger? That might diminish the life of the batteries as well. And reduce overall efficiency by converting AC to DC for charging and then back to AC through inverter...there's got to be some loss there.

Can anybody confirm my two dislikes above?
Also, if that is the case then I'm wondering if it really is cause for concern or I'm just being too picky. Do all these AIO units basically work this way, or are there some that have a "smart switch" that somehow runs the basics off grid when it's up but switches to battery/solar/inverter only when the grid is down?

 

[AmpD]

I don’t regret owning a kill-o-watt meter at all. It gives real world working numbers over time in your specific environment.

I too started with an estimate based on daily total usage. Once you start seeing how it all works a few exact numbers are going to come in handy!

Still in planning and purchasing stages here. Good luck and welcome to the forum. ?

 

[theoldwizard1]

The commonly used solution is to use a hybrid inverter and and a critical load panel in addition to the house panel. When the grid is off, the system is on battery, and you can not expecting the battery to energize every load in the house, ...

I would not say that ! It depends on how small the cabin is, what size are the loads, the size of the battery bank and how long of a run time you want.

If you biggest load are a coffee maker, microwave and maybe an induction cook top, there is not reason your hybrid inverter can not feed the entire house.

There are many manufacturers that make inverter/charger/automatic transfer switches. Easy to install. Output goes to you main panel. They get expensive if you need 240VAC !

 

[NCislander]

I also live in the same region of NC as you. I went with Growatt ES 5000 AIO Inverter units. I have (2) of these units paralled/stacked. I plan to add a 3rd unit in 2024. Also plan to expand battery storage and solar panel capacity as time & budget allow.
I'm very happy with the performance.
Good luck on your build.

 

[OzSolar]

Is this a part time property?

One thing I would add to the decision matrix is remote monitoring, it would also be nice to change parameters remotely. Some equipment has it built while some does not.

 

[Nikg736]

This is a part-time property. We do short-term rentals and unfortunately only get out there ourselves every so often. Really just want the option to have backup power to run essentials when the grid goes down.

Do the Growatt systems only switch over to the inverter when the grid is down?

 

[timselectric]

You can set them up to operate that way if you want.

 

[Nikg736]

MPP - the "zero transfer time" of these units appear to be due to them always being on and always running whatever is hooked to them through the inverter. I'm assuming there is no way to circumvent that. If trying to achieve mostly solar operation from a system, then that's reasonable. But for my application wouldn't this just run the inverter all the time unnecessarily and burn it out quicker? How long do inverters usually last? If they last 10 years of constant use then its not a concern for me, but if that answer is more like 3-4 years I'd rather have something that only switches on when called upon.

 

[Nikg736]

So, I may have found a source of battery storage for pretty cheap. See below.

Panasonic (Sanyo) Modules

These are 300wh for $20 and are 13s lithium 18650 cells, so I figure that should be OK for use with a 48v AIO unit?
Now my question...would it be possible, reasonable and relatively safe to just get a whole bunch of these (say 50 modules) and skip the solar panels for now? Grid power would charge these up and then when power is down they supply the backup. In the future, add solar panels. But this would definitely keep things simpler and quicker in the meantime.

My only concern would be connecting lots of these in parallel, but with so many units I figure there really wouldn't be much amps flowing through any single module. Plus the construction shows what appears to be fused connections to each cell on the existing tin strips. I saw a picture or video somewhere that showed how to "stack" busbars or nickel strips in a kind of "pyramid" configuration and that way more metal was built up where amps would be greater. Anybody seen this or know what I am talking about? Is it unreasonable to parallel so many of these provided there is adequate copper where the greatest current would flow?