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Inverter without solar (yet). Recommendations?

BBMitch

New Member
Joined
Apr 4, 2023
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4
Location
Vancouver, British Columbia, Canada
First pidt, if I've put this in the wrong section please let me know. Thanks in advance to any who have thoughts.



I live in a trailer. This brings several challenges. I'm far from shore power. Increased power draw means an ever decreasing voltage drop. Plus everything downstream works harder. That said solar is probably not an option in my current location. I need more power but only intermittently. When I do, my supply voltage can drop to 85V.



Enter the utility shed. It's outside my living space and contains my washer and dryer. I router my shorepower there (1 x 120V/20A + 1 x 120V/15A).



I'd like to build a 48V 120V battery inverter system with the possibility of future solar support. I'd like to top charge from one or both of my power feeds, and use only inverted power. This power should be 120V - it does not have to be on a single bus, but at least 30A has to be available for the trailer. With ideally at least another two 15A circuits for use outside the trailer (I cook outside, washer, dryer are outside, and yes my dryer is 120V apartment size).



So probably looking at 7200W.



Will seems pretty happy with the EG4 systems from a value and function standpoint. Would they work with solar offline? Can they charge from mains? Or are there other systems I should consider?



Price is a big consideration. I don't mind doing more work, and I can run wire (ice worked with low and high voltage, and feel I could do anything including building from cells). But if I save a month of time and get a warranty I'm not too proud to choose the smart way.



My annual consumption averages around 400KWh a month. But that's the part I measure (in trailer). So it might be closer to 500KWh.



Ideally I'd like to be able to use one, or two shore power options. Even possibly considering adding a generator in the future but that could use one of the shore power inputs. So if for example I had only 15A shorepower I could run the generator during daylight for a couple hours to charge up for the over night quiet time.



At some point I want solar. But where I am now the trees make it unlikely until I move.



Thoughts? Advice? Discreet build with batteries and seperate mppt chargers with an inverter or is there a single unit which I could just add a second mppt to?



Btw I have about 24"x24"x60" to build in. I figure that should allow enough room? And the waste heat will keep my laundry machines from freezing in the winter ??



Thanks!
 
Just messing with numbers:

So probably looking at 7200W.
My annual consumption averages around 400KWh a month. But that's the part I measure (in trailer). So it might be closer to 500KWh.
500kWh / 30 days = 16.6kWh / day

To store this in a 48V (51.6V nominal) battery:
16600Wh / 51.6V = 321Ah of battery

To recharge this from empty in a 5h solar day:
16600Wh / 5h = 3320W of solar operating at 100% efficiency

3320W of solar / 58V charging = 57A solar charger (quite reasonable)
 
Just messing with numbers:



500kWh / 30 days = 16.6kWh / day

To store this in a 48V (51.6V nominal) battery:
16600Wh / 51.6V = 321Ah of battery

To recharge this from empty in a 5h solar day:
16600Wh / 5h = 3320W of solar operating at 100% efficiency

3320W of solar / 58V charging = 57A solar charger (quite reasonable)
Yes that's what I think, BUT I am surrounded by trees. So I want to charge from shorepower over the batteries and inver for running. Probably plan for a little growth but not much, but if I move with less coverage I could look at adding panels. Most of my questions/ quandary is about selecting gear. I.e. could I use a solar system without solar and a second mppt charger for my secondary shorepower etc.

Your numbers make sense to me, but 11 big panels to get that wattage. Even if I start with some solar I will need some shorepower charging here. Canada. Long winters.
 
With the large voltage drop (and possible frequency shift) that is happening under more serious loads, then most likely you will want to:
- Use one ( or more ) dedicated 120 vac charger to supply power to the batteries as these are fairly tolerant to incoming power imperfections
- Use a dedicated 120 vac inverter that is robust enough to run the heavier loads off of the battery pack

It might be useful to break the total load into ~ 2 or 3 000 watt "chunks".

- That is a common size of inverter with reasonable wire sizes.
- If you have a few vs only one, then this adds some redundancy / ability to deal with failures
- The output of a good quality 2 000 watt inverter is ~ 17 - 20 amps and many of them have built in output protection. This can make it viable to just protect that circuit with a GFCI outlet vs having to use a breaker panel.

- If it snows there, then it makes sense to consider good quality AGM batteries instead of LiFe.

With this setup, it would be easy to later add more chargers, regardless of 120 vac, 240 vac, generators, 48 volt generators or solar as the opportunities become available.

You will need to look at the specs for "all in one" or combo inverter / charger units to see if they can really deal with poor quality incoming power. Usually they can't.
 
Couldn't quite follow all the "shore power (or lack of)" comments ... what power feeds to what locations, exactly (if you can share)?

l'd do the following (unless there are restrictions, constraints?):
- add heat to the shed ... could be propane heater, thermostat-driven (this is how I heat my "utility shed")
- add generator (inverter-gen if possible) ... can be in an enclosure adjacent to shed, to prevent noise ... choose fuel type for your location, but propane is less messy, and fits the heat scenario above

Then, in the 2'x2'x5' space, build up a LiFePO4 battery bank on the bottom, an AIO inverter at the top, and all other connectors/etc in between. Not much different from a 24v or 48v "solar generator" (fits the same kind of space), just not on a mobile hand-truck ... could be a wall-mounted rack, or shelving system.

Grid power (inverter-gen) feeds AIO when needed (possibly 4 hours out of 24) until solar gets sorted out; spare power for occasional big loads.

Hope this helps ...
 
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