Factoring a portable generator into solar setup

[KXJOE]

Hey Guys, I am new to this group and am a beginner on the solar energy platform. So just a little background. I have a small off grid cabin where I have used a generator for years for my electric energy needs. I have been wanting to go solar for awhile but just never got around to it. So... within the year I ended up having to totally rebuild my site including tearing down the old structure and building a small cabin (14' X 30'). At the moment the walls and ceiling are still open framing with insulation (no drywall yet) So I figure now is the time to set up a solar system. I don`t have any hands on solar experience so for the last couple of months I have been reading and watching a ton of information on the topic. Now, I do have experience with construction. I own a general contracting business that does renovations in the commercial and residential field and with that said I have done quite a bit of work in just about every trade. I am NOT an electrician but have done a fair share electrical work on the smaller scale. I am planning on doing all of the electrical work in my new cabin and running all circuits into a service panel box that I may power from my generator for the time being (I figure it may take awhile to get setup with the solar) and also figure that larger electrical items are going to need the generator to power them at least until I feel out the solar and get more comfortable with it. So my ultimate goal would be to run solar on things at night during quiet time (lights, TV, laptop, etc.) During the day I don`t mind running the generator for things like microwave, A/C, etc. My main question for you folks that have the experience that I don`t have is can I incorporate my generator with my solar system, that way if my batteries run down due to bad days with sunlight ( I am surrounded by trees in the woods) I would like to be able to charge the batteries with the generator. I have seen some inverters that can connect to shore power. I don`t believe the one I have at the moment will do that but Hey you guys would know better than me so let me know. What I have gathered together at the moment for the solar equipment is the following:
* Six 100 watt solar panels
* Victron MPPT 150 volt / 45 amp controller
* GIANDEL 3000W Pure Sine Wave Power Inverter 24 volt
* Four 100ah lithium batteries
I have yet to purchase all the other stuff (fuses, circuit breakers, wire, connectors, etc.) but will be getting around to that soon.
Any knowledge you guys can give me with the setup would be greatly appreciated including critiquing my selection of equipment if you feel it should be different. I don`t think I have a terrible amount of electrical demands in the cabin and possibly may be able to power more that just the light and TV on the solar system but not trying to reach too far. The electrical components that I have in the cabin are as follows: Interior LED recessed lights, some LED string lights on the exterior, TV, Laptop, Microwave oven, Stereo, Small in-line AC water pump, Small propane tankless water heater, Two ceiling fans and a window inverter air conditioner. As I said before I am not looking to expect to power all of this stuff on only the solar, maybe as time goes on and as I build on to the solar system but for the moment I would like to still use my generator, I have a 8500 watt inverter generator that pretty quiet but that`s relative depending on who is hearing it.
I am open to any and all advice from you guys. Sorry for going long with this post and Thanks again for letting me be apart of this forum I am sure I am going to learn a lot.

 

[MaikaiLifeDIY]

To address, what appears to be your main question, YES you can use your generator to charge your batteries or to run the cabin.

In my home I have the option for both, I have a transfer switch to let the generator power the entire house, bypassing the solar system, or I can use the generator to provide energy to the Inverter, which can then both feed the house and recharge the batteries.

With the equipment you have listed above you can run your cabin off the generator, but you cannot charge your solar system batteries. Your only method of charging your batteries is using your Victron MPPT which can only accept power from your solar panels.

If you want to stick with the Victron brand, (which is great stuff), this would be a better device that might be simpler for your cabin needs and would allow you to use your generator for charging.

https://www.victronenergy.com/upload/documents/Datasheet-EasySolar-1600VA-EN.pdf

EasySolar - Victron Energy

Combine a MPPT Solar Charge Controller, an inverter/charger and AC distribution in one enclosure with the EasySolar. Find a dealer near you.

www.victronenergy.com

 

[MaikaiLifeDIY]

This is another really good all-in-one inverter solution

EG4 6000XP Off-Grid Inverter | 8000W PV Input | 6000W Output | 480V VOC Input | 48V 120/240V Split Phase | All-In-One Solar Inverter

The EG4 6000XP is a cutting-edge 48V split-phase, off-grid inverter and charger, designed to revolutionize your energy needs. With an impressive 8kW of PV input capacity and an efficient 6kW continuous power output, it also serves as a battery 140A charger. What sets it apart is its scalability...

signaturesolar.com

 

[Rocketman]

It is usually best to design the system on paper before you start buying stuff - saves purchasing mistakes.

I assume you are planning on a 24v system (because the inverter you purchased is 24v). Can the lithium batteries you purchased be placed in series for 24v? (Most can - some cannot). Assuming they can…

I use a Victron Multiplus 3000 for my MotorHome. It works great - runs off battery-when grid/generator happen it seamlessly connects, and also when the generator shuts down - I don’t notice it inside the rig (nonthing flickers). This will run one large item (from battery) at a time - microwave. Or as many as you want on generator (more than 50amps @120v). Look into a Multiplus 24/3000.

I would also get a Smartshunt or BMV712. This is a battery monitor- so you know if your batteries are mostly full or mostly empty.

And get the Cerbo (and touch) - this brings all the information from all the Victron devices together into one screen so ANYONE can understand what is happening and what they can or cannot do.

Solar: you will need more than 600w of solar - but it is a start. 100w panels usually are much more expensive (per watt) than other panels. Look into 330+ watt panels.

The 600w will help reduce your generator time. On my MotorHome I have 1500w and we only run the generator occasionally or for air conditioning. With the 600w my guess is you will only need to run the generator for an hour in the morning and an hour at night (unless the A/C is on or you are doing a lot of cooking).

As you are planning you may want more batteries- so leave room for them.

The Multiplus 24/3000 you can have a bunch of small things on - but only one big thing. If we are running the microwave (large item) and add a medium sized item (toaster), we overload and the Multiplus shuts down for 1 minute. If I was in a cabin, I would go with the 24/5000 or 48v/5000 - that way microwave and hairdryer can both be on - but that will take more batteries.

Also it is usually best to have the battery voltage equal the inverter voltage - 24v batteries for a 24v inverter or 48v batteries for a 48v inverter- save battery imbalance issues. So any future battery purchases look into that.

For bus bars look at the Victron PowerIn and add fuses (see YouTube). I would have all the batteries on a PowerIn - then the shunt and main shutoff- then another one (or two) PowerIn going to the loads and mppt’s.


Good Luck with your project

 

[KXJOE]

Thanks MaikaiLifeDIY,
So the EasySolar does the controller and inverter as one package, I like that, but it looks like it is meant for a euro 230 power grid (at least the one I was looking at). I am on the East coast in the US. It may not matter since I would be pulling from a generator that would have the option of the 240 circuit. The price is a little steep and may be out of my immediate budget on this first approach in the solar game but maybe on the next set up. I like your idea of the transfer switch, I have seen the ATS (auto transfer switch) but my application would probably better if it was manual as I don`t have a generator that would automatically start up (if I am understanding the ATS correctly) But I would love to have a manual switch that I could change over to the generator. As far as charging the batteries, is there a separate charging device that could charge the batteries from the generator and would I have to disconnect them from the Victron controller first ? Thanks again for for advise

 

[pollenface]

I use a 1kva generator with a 20a dumb charger when needed.

With 24v you can use 2x 12v chargers

 

[KXJOE]

Thanks so much Rocketman,
Very informative and helpful information there.
Yes, I am planning on running the batteries in series and I do believe they are capable. One question, if I have my six100 watt panel in place, when I go to add more would I be able to connect the 330watt panels in line with the 100 watt panels ? This my first project working with solar so trying to work with what I have unless I can`t. I`m sure the next time around I will be much more informed and purchases will be much better. The Multiplus 24/3000 looks great. Thanks for the advise on the other accessories

 

[MaikaiLifeDIY]

I wasn't recommending an auto transfer switch, this is what I have. As you can see either way UP or DOWN is Live but from difference sources.



In my house here is how it's wired.

 

[KXJOE]

I wasn't recommending an auto transfer switch, this is what I have. As you can see either way UP or DOWN is Live but from difference sources.

View attachment 180041

In my house here is how it's wired.

View attachment 180042

Got it, So with the disconnect in the up position gives generator power and down is the solar. Nice !

 

[Rocketman]

For combining different panels into one mppt.

Yes you can but there is a penalty, how big or little of a penalty depends on matching the proper electrical specs up. When you get ready learn how before buying the new panels. (You have enough on your plate right now),

I wanted to add another 210 w panel to one of my arrays however, I was out of big spaces and they quit making the panels I had on that array. I was able to put two 100w panels in parallel and then connect them in series to the other two 210w panels. Out of a possible 620w my penalty is I can only get something like 590w - I was very amazed that I found almost the perfect panels to work and the penalty was so small - usually it is more like 8 to 10% - it all depends on the math.

 

[StanC]

It is usually best to design the system on paper before you start buying stuff - saves purchasing mistakes.

I assume you are planning on a 24v system (because the inverter you purchased is 24v). Can the lithium batteries you purchased be placed in series for 24v? (Most can - some cannot). Assuming they can…

I use a Victron Multiplus 3000 for my MotorHome. It works great - runs off battery-when grid/generator happen it seamlessly connects, and also when the generator shuts down - I don’t notice it inside the rig (nonthing flickers). This will run one large item (from battery) at a time - microwave. Or as many as you want on generator (more than 50amps @120v). Look into a Multiplus 24/3000.

I would also get a Smartshunt or BMV712. This is a battery monitor- so you know if your batteries are mostly full or mostly empty.

And get the Cerbo (and touch) - this brings all the information from all the Victron devices together into one screen so ANYONE can understand what is happening and what they can or cannot do.

Solar: you will need more than 600w of solar - but it is a start. 100w panels usually are much more expensive (per watt) than other panels. Look into 330+ watt panels.

The 600w will help reduce your generator time. On my MotorHome I have 1500w and we only run the generator occasionally or for air conditioning. With the 600w my guess is you will only need to run the generator for an hour in the morning and an hour at night (unless the A/C is on or you are doing a lot of cooking).

As you are planning you may want more batteries- so leave room for them.

The Multiplus 24/3000 you can have a bunch of small things on - but only one big thing. If we are running the microwave (large item) and add a medium sized item (toaster), we overload and the Multiplus shuts down for 1 minute. If I was in a cabin, I would go with the 24/5000 or 48v/5000 - that way microwave and hairdryer can both be on - but that will take more batteries.

Also it is usually best to have the battery voltage equal the inverter voltage - 24v batteries for a 24v inverter or 48v batteries for a 48v inverter- save battery imbalance issues. So any future battery purchases look into that.

For bus bars look at the Victron PowerIn and add fuses (see YouTube). I would have all the batteries on a PowerIn - then the shunt and main shutoff- then another one (or two) PowerIn going to the loads and mppt’s.


Good Luck with your project

Thanks for sharing your setup - I'm thinking of something very similar for my travel trailer. When off-grid, do you connect your generator to the AC input on the Multiplus II jus like it was the grid? And the MultiPlus balances the power input from the solar and the gen to charge the batteries with the excess power? Thanks!

 

[Rocketman]

Thanks for sharing your setup - I'm thinking of something very similar for my travel trailer. When off-grid, do you connect your generator to the AC input on the Multiplus II just like it was the grid? And the MultiPlus balances the power input from the solar and the gen to charge the batteries with the excess power? Thanks!

On RV’s you need a transfer switch- it switches both the hot, and neutral between shore and generator. (You need to switch both to keep the Neutral-Ground bond correct). On all that I have had it gives priority to the generator (built in generators). If you have just a portable generator- then you act as a manual transfer switch.

On the Multiplus you set the AC input amps accordingly to the source. From 7.5a to 50a - depending on how much load can be handled.

Lithium batteries can handle a tremendous amount of charge. I have a 544ah pack- the manufacturer says it can be charged at .5C- so 272amps.
My Multiplus will charge at 120a
800w mppt 100/50 can charge at 50a
600w mppt 100/30 can charge at 30a
Dc-Dc charger can charge at 30a

So technically I could charge at 230a if my generator was running while driving and in great solar conditions around noon. That would be .42C - in reality I don’t worry about it and the most I ever charge is grid/generator 100a plus poor solar - maybe 25a - so I am always below .25C.

If you are connected to the grid all the time - there are some ways to prioritize solar. You can setup the Cerbo so it ignores grid until the battery get to ____% (user setable) state of charge or the loads exceed_____watts(user setable).

Good Luck