Running 2 Honda Generators in Parallel

New_Mexico_Will · September 2020

I've been building my 48 volt system for the better part of a year, learning as I go. I learned quite a bit just lurking here before I officially joined. My system is up and running as of this past weekend, consisting of 1.6kw of panels (soon to be 3.2kw), an AIMS 6,000 watt inverter charger, 9.6kwh of hybrid gel batteries. I do have grid power on the property, but am looking to discontinue using it completely. Currently is is only used for my laundry, well pump, and RV. My cabin is completely running on the solar.

In order to feel confident ditching the grid power, I'd like to have a generator, which is far more reliable than our grid anyway. I'm looking at the Honda EU2200ITA1. It produces 1800 rated, 2200 surge watts. It is capable of being paralleled. Ok, enough rambling, here's my question:

If I get 2 of them and run them in parallel, will I get exactly double the watts? Can my inverter start both of them, or does one start the other? I need over 3000 watts going to the inverter to get it to charge the batteries, so 2 of these seems ideal. Why 2? I'll be completely off-grid, so redundancy is very important. I appreciate any answers/input/advice for my scenario. Thanks!

BB. · September 2020

I understand the siren call of being completely off grid... HOWEVER, unless you have very high per month connnection fees--I suggest that you keep the utility power (even if you don't use much). For me, it is ~$5-$10 per month minimum charge (in expensive California). I have read of folks that are closer to $48 per month, and some noise about utilities moving upwards to $96 per month or so (this is to make "GT Solar" power systems less cost competitive--"Cheap" per $/kWH pricing, but high connection charges).

So--Make an informed decision before disconnecting. If your connection charge is "cheap", it is cheaper than buying a backup genset (or second backup genset---Although, I cannot say much here--I have two gensets + GT Solar + Utility power--Because California has proved itself incompetent on supplying energy--Wild fires, prescriptive shutdowns to reduce wild fires, and simply dumping reliable fossil fuel and nuclear power plants--And running out of power on hot summer days).

Things to think about... Will they pull power lines and poles to your property? No connection, no need for poles and lines. What would it cost to reconnect (if they have to run new transformer and lines, could cost thousands--Or they may just refuse as parts of the country depopulate/no subsidies for rural electrification anymore). Would you be able to subdivide the property and sell pieces without utility power (whatever happens in the future).

What would be the value of the property if no power lines. Solar systems may be "worth it" to you--But most buyers see solar as a "don't care" or are actually concerned about the wires on the roof/batteries/etc. and may pay less.

What happens as you get old (may you have a long and productive life). Will you and/or your spouse/family be able to maintain the system (battery replacement every X years, etc.). Assume you replace the batteries every 5-10 years, inverter+charge controllers every 10+ years--Money in savings for doing your own expected and unexpected maintenance?

Anyway--Back to your questions... The Honda eu2x000 family are all manual start (pull cord) gensets. There is no auto/remote start (have seen some folks, in times past, adding an electric starter--But that is not stock (that I know of). Yes, you can put two of them in parallel, and with both running, they will add their output power together (there are some issues/limitations mixing old eu2000i with new eu2x00i and eux000i together. Newer units can mix/match with different power output ratings (to a limit).

All the smaller Hondas are 120 VAC only. Do you have need for 120/240 VAC now or in the future (some inverter-chargers support 120 or 120/240 VAC input, others must have 120/240 VAC to charge batteries/run inverter).

Do you need "quiet power" (eu family or similar)--Or could nosier/open frame gensets work for you (with remote start/some have auto choke, proper remote start controllers). The "basic" Hondas usually need manual choke to start. There are models that have fuel controllers (no manual choke). And others have even setup a remote solenoid to automate the Honda Choke.

I am not a big fan of auto start systems... While they seem nice, they also can fail in new, wild, and wonderful ways. If you are doing your own design and maintenance, you will probably become somewhat of an expert to configure and maintain your auto start systems.

Some (few, many, most?) inverter-chargers have a maximum AC Current input--And you can program them to take more or less current, depending on what size genset you have connected.

Do you need an "inverter" genset... They are quiet and reliable. But, if the noise does not bother you (remote shed, no other homes nearby), I am not sure that they offer much for you... Any (gasoline, propane) genset running >~50% rated capacity is pretty fuel efficient). For bulk battery charging, running around 80% of genset capacity (for residential types) is a good setting. And once the battery bank gets over ~80% State of Charge, you might just turn oft the genset and let solar continue charging (or startup genset next morning, if needed). Running a standard genset at less than ~50 rated power, they are much less efficient. Typical gasoline genset consume around 50% fuel flow at 0% to 50% of rated load. Inverter generators are pretty fuel efficient down to 25% or less of rated load ("eco throttle" for Honda and others).

Diesel gensets are fuel efficient below 50% of rated output (but running at low output power can cause other issues with diesel engines).

Adding more solar panels, and not even having a backup genset (other than a simple one for real emergency use--I.e., your inverter fails), can work for many people. But you need to look at your power needs (can you turnoff your home loads during bad weather, or are you--for example--running a business and you need power 8x7 or 24x7--And a genset is a necessity). Then design your array/battery bank/inverter/chargers/backup power as needed.

I know that this is a solar/wind forum. But I/we want people to make informed decisions. Going off grid is a big lifestyle choice--And lots of issues can some with that choice. Using GEL batteries (some GEL batteries will only take reduced charging current like C/20--Not good for solar), (some) AIMS inverters, and small residential/portable gensets, etc. -- That may be a lot of maintenance down the road. Going with integrated solar charge controller/AC inverter/monitoring systems (remote/Internet capable) can be nice too (but not cheap).

-Bill

New_Mexico_Will · September 2020

Wow, detailed response, thank you. You bring up some excellent points that I hadn't considered.

My cost without using a watt is $25/month. That does seem like a small price to pay given the considerations you mentioned, however the physical location of the power on my property (800 feet or so) from my inverter would make it expensive to get power there. Probably cheaper to buy a generator than to do that.

Another thing I didn't think about until reading your response is that our very rural area is maxed out on grid power, so no new construction on the property between mine and the county road unless I let them pull from my transformer. If I ditch it, that opens up the possibility of building where I'd rather not have it.

I looked at so many generators, I just got mixed up. I don't mind pull starting it, but would prefer remote electric start. Back to the drawing board on that. You make a good point for a manual start one.

I was under the impression that inverter generators provided much cleaner power that is necessary for input to an inverter charger. I can make as much noise as I want, nobody nearby. I often run a loud generator for power demands around the property.

My inverter manual states that it needs 25 amps (3,000 watts) to charge the batteries as long as there is no load on the inverter. So, I'd like to have at least 4,000 watts so I can use a little power while running the generator if necessary. For full power availability while charging batteries, I would need 75 amps, or 9,000 watts, but that isn't necessary. Honestly a couple grand for a generator is pretty minor compared to what I've invested in solar.

I'm not concerned about resale. Anybody living out in the boonies where I am would not be your "average" person, and solar would likely be a selling point.

My battery bank is rated to take up to 60 amps charge. 4S2P. I wont give it more than about 30. They are the new Renogy AGM GEL batteries. It is all up and running fine for the past week, so I'm not looking to upgrade yet, and I do prefer separate components. That just seems like a better idea off grid to me. I am also running 2 charge controllers, again for the redundancy.

My "grid" only consists of an RV pedestal that I had installed when I bought the property, which was vacant desert land. Now that I've finished building my cabin, I'm not using the RV.

Thank you Bill, you gave me some great things to think about.

BB. · September 2020

Regarding burying cable... You can get 500 feet of 4/0 aluminum cable, direct burial, for $1,200. (link is FYI, I am not an electrician, nor can I tell you what is required for code in your area):

https://www.homedepot.com/p/Southwire-500-ft-4-0-4-0-4-0-Black-Stranded-AL-Monmouth-URD-Cable-55418321/202562800

And if you go with 3% maximum drop @ 800 feet, roughly:

https://www.calculator.net/voltage-drop-calculator.html?material=aluminum&wiresize=0.1608&voltage=240&phase=ac&noofconductor=1&distance=800&distanceunit=feet&amperes=60&x=0&y=0

60 Amps will give around 3.1% drop (aluminum 4/0) @ 240 VAC (14 kWatt).

Of course, if you have rocky ground, that may not be an easy dig (or other environmental issues).

Ideally, it would be nice to run a higher voltage from the pole to your home and drop to 120/240 VAC with a local transformer outside--But that depends on what you need/want/$$$ spent/local codes/etc.

Inverter generators are nice--Very stable AC frequency. However they usually supply less surge current and have a bit more losses at high loading. With modern electronics these days, frequency is not usually a big issue (modern electronics generally change from AC to DC power anyway for computers, TVs, etc.).

And most AC inverter-chargers will open up the frequency to 60 +/- 5 Hz or so--Which most generic modern AC generators (non-inverter type) can support.

This is a very interesting read... It is about Movie Lighting and Equipment running on generators:

http://www.screenlightandgrip.com/html/emailnewsletter_generators.html

Keeping the RV connection at the edge of your property may be great for guest hook-up too. Possibly a shop/outbuilding/garage in the future?

-Bill

New_Mexico_Will · September 2020

Ha! You read my mind. I think I will keep it for a future shop and guest RV hookup. My welder will tax my solar setup for sure. I just like the idea of not being connected, so I'll probably keep it that way for the house. I forgot that I have a lot of aluminum cable left over from the electric hookup that the electric company left on my property after the initial hookup. I should lay that out and measure it, although I'll probably just sell it. Code in my area is kind of whatever you want. It's still the wild wild west out here.

New_Mexico_Will · September 2020

The cable left behind

mike95490 · September 2020

Yes, for the Inverter to qualify the generator, it must be an inverter generator. (some inverters have a AC2 or Generator input with relaxed voltage and freq specs to allow for any generator)
AND
If the inverter can provide 240VAC, your generator usually needs to be a 240V version.

If you need over 3kw for charging, and you can config the inverter to use relaxed input window, then may as well get a conventional 4 or 5kw generator with electric start, and maybe you want a small harbor freight inverter generator if you need something small for a pot of coffee...

New_Mexico_Will · September 2020

I buy plenty of things at Harbor Freight, but an inverter would not be one of them!

New_Mexico_Will · October 2020

I found this website selling add on remote start functions for the Honda generators discussed:

http://www.generator-line.com/index.html

Running 2 Honda Generators in Parallel

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