DIY portable generator ideas and opinions

[LBART]

I have thought about a solar system for years but only started getting serious recently. After a recent ice storm left us without power for 44 hrs I knew it was time to do something. I started watching tons of videos and researching products. Initially I wanted cheap and easy 12v but soon after the videos I was sure the 24v was best for me, I thought 48v would be overkill unless I went to the full/partial home system. Then in another thread I received a link from Danke on a video for a 3000W solar power cart. Out of curiosity I started researching 48v and now I am leaning that way.

With the changes due to researhing options I think I am doing fine and haven't spent money on things only to decide on something else.

So now looking for advice and opinions on a 48v system. Here is what I am thinking of right now. And to maintain one key brand instead of mixing brands.
EG4-LL Lithium Battery (V2) | 48V 100AH | Server Rack Battery $1700
EG4 3kW Off-Grid Inverter | 3000EHV-48 | 3000W Output | 5000W PV Input | 500 VOC Input $675
(Pre-Assembled) EG4 Enclosed Battery Rack | 3 Slot | Wheels Included $550
12V 200 Watt Bifacial Solar Panel 10BB Mono High Efficiency Solar Panels 4 at $185 each

My thoughts on portable is temp home use, taking out in the yard instead of stretching out multiple extension cords and taking camping. Plus learning before the bigger home investment.

The rack runs it up a bit but allows for future expansion and would be beneficial for converting to a off-grid home system. There would be other upgrades needed then.

 

[Rocketman]

I agree 48v is best in your case.

I can’t comment on your other equipment choices - excep solar panels. Here are a few thoughts as I was reading your plan.

800w seems a bit low…

If you decide to add more panels in the future you may not be able to find the exact same panels or electrically similar panels.

$.925 cents per watt is very high for panels. See if you can find cheaper ones through Craigslist or classifieds. Also Suntan solar has used ones that are really cheap if you can pick them up. 330w panels I believe are much cheaper. - if you can find a local place for pickup.

Good Luck with your project.

 

[50ShadesOfDirt]

Portable seems like a hand-truck with correct wheels for use case (camping, etc.), whereas rollable seems like the rack-mount system you've got ... it will roll around the shop's concrete floor, and that's about it.

Beyond that, 12v/24v/48v has always seemed (to me) to be a choice between loads, complexity, and costs. I would look at each reference voltage design that fits your well-defined *use case*, until something knocks it out for you. That could be cabling, cost of components, number of batteries or packaging ... or even color.

As my use case was camping and portable power around the property (acreage), I needed a hand-truck to fit camping/property use (big fat wheels). Then, I went with 2 x 12v100ah batteries at bottom (24v cfg), and mpp 24v all-in-one at top, with some 2x4 lumber magic. It all stays as skinny as the hand-truck wheelbase. Less than $1400 later (at today's major component pricing), I was done with the basics, and the mpp powered right up. I think it will work for both camping and around-the-property. I think it would also work for apartment or home for light-weight emergency duty, or any portable/emergency "onsite power" requirement.

For me, and for my particular (very portable hand-truck) use case, a 48v design got blown with costs, weight, etc.

Add a charging source (grid power at home, gen backup, solar panels) for any use case. The all-in-one inverter eats them all.

Whatever reference voltage is left after your design/planning is what you roll with ...

You could also "start with 48v" as the design premise, and I think many folks go this route first. This is never overkill, until something knocks it out for you or your use case, as 48v is best in pure terms of capacity & such. If nothing really knocks it out for you, then stick with 48v ...

 

[oldmaninsaline]

May or may not be pertinent to your design process but keep in mind any battery has weight so you'll want a wheeled case.

In my case when I was designing my power station, the first thing I did was lay out all the components and determine the footprint I needed before I went all willy nilly and ordered a case for the system. For me, with two 100 ah cell packs, inverter, charge controller, shunt, etc.., the optimal case was the Seahorse 920SE.

 

[Browse]

EG4-LL Lithium Battery (V2) | 48V 100AH | Server Rack Battery $1700
EG4 3kW Off-Grid Inverter | 3000EHV-48 | 3000W Output | 5000W PV Input | 500 VOC Input $675
(Pre-Assembled) EG4 Enclosed Battery Rack | 3 Slot | Wheels Included $550
12V 200 Watt Bifacial Solar Panel 10BB Mono High Efficiency Solar Panels 4 at $185 each

Those panels won't supply enough voltage to meet the minimum MPPT input level of 120VDC.

 

[LBART]

I agree 48v is best in your case.

I can’t comment on your other equipment choices - excep solar panels. Here are a few thoughts as I was reading your plan.

800w seems a bit low…

If you decide to add more panels in the future you may not be able to find the exact same panels or electrically similar panels.

$.925 cents per watt is very high for panels. See if you can find cheaper ones through Craigslist or classifieds. Also Suntan solar has used ones that are really cheap if you can pick them up. 330w panels I believe are much cheaper. - if you can find a local place for pickup.

Good Luck with your project.

I was also looking at the physical size and weight. I would hinge a pair together so I could take them out in pairs. These are the bifacial and I am in Wisconsin so with some snow I was hoping for a little due to the reflective on the rear. I also figure I would buy the panels in a separate purchase since they are from 2 companies. I will look at Suntan solar.

 

[LBART]

Portable seems like a hand-truck with correct wheels for use case (camping, etc.), whereas rollable seems like the rack-mount system you've got ... it will roll around the shop's concrete floor, and that's about it.

Beyond that, 12v/24v/48v has always seemed (to me) to be a choice between loads, complexity, and costs. I would look at each reference voltage design that fits your well-defined *use case*, until something knocks it out for you. That could be cabling, cost of components, number of batteries or packaging ... or even color.

As my use case was camping and portable power around the property (acreage), I needed a hand-truck to fit camping/property use (big fat wheels). Then, I went with 2 x 12v100ah batteries at bottom (24v cfg), and mpp 24v all-in-one at top, with some 2x4 lumber magic. It all stays as skinny as the hand-truck wheelbase. Less than $1400 later (at today's major component pricing), I was done with the basics, and the mpp powered right up. I think it will work for both camping and around-the-property. I think it would also work for apartment or home for light-weight emergency duty, or any portable/emergency "onsite power" requirement.

For me, and for my particular (very portable hand-truck) use case, a 48v design got blown with costs, weight, etc.

Add a charging source (grid power at home, gen backup, solar panels) for any use case. The all-in-one inverter eats them all.

Whatever reference voltage is left after your design/planning is what you roll with ...

You could also "start with 48v" as the design premise, and I think many folks go this route first. This is never overkill, until something knocks it out for you or your use case, as 48v is best in pure terms of capacity & such. If nothing really knocks it out for you, then stick with 48v ...

When considering the 24v I was also looking about the same power so 200Ah that blows past the $1400 for the batteries alone. I already have a hand truck so if the box was too big I could set it up there and have the rack box just sitting around. I was figuring not putting on the wheels and moving it with the hand truck. The all in one seems easier and less expensive in my research. I was looking at the Victron for the SCC and it matters for each voltage rating so it gets pricey really quick.

 

[LBART]

May or may not be pertinent to your design process but keep in mind any battery has weight so you'll want a wheeled case.

In my case when I was designing my power station, the first thing I did was lay out all the components and determine the footprint I needed before I went all willy nilly and ordered a case for the system. For me, with two 100 ah cell packs, inverter, charge controller, shunt, etc.., the optimal case was the Seahorse 920SE.

View attachment 139669

View attachment 139670

Your case looks compact but also very complicated. I watched several battery teardowns and most of the cheaper batteries were crap when Will tore them down. He was really impressed with the EG4 server rack battery and the price point overall wasn't that much different with both the 24v 200Ah and the 48v 100Ah costing the same.

 

[12VoltInstalls]

use case

That is a post-modern catch phrase that should be banned LOL
Many one-word preexisting english language descriptors convey meaning much better.

800w seems a bit low

Absolutely too low. I have a small system but it’s sufficient for my needs- with sunshine - so Oct to (this year) March 800W doesn’t make the cloudy days.

 

[LBART]

Those panels won't supply enough voltage to meet the minimum MPPT input level of 120VDC.

How much solar would be recommended?

 

[LBART]

That is a post-modern catch phrase that should be banned LOL
Many one-word preexisting english language descriptors convey meaning much better.

Absolutely too low. I have a small system but it’s sufficient for my needs- with sunshine - so Oct to (this year) March 800W doesn’t make the cloudy days.

How much solar would you recommend? I am fine with series or a series/parallel.

 

[Browse]

Your panel Vmp is around 23V, so 120V/23V = 5.2 panels, so you would round up to 6 panels to make sure you will be above the lower cutoff of your inverter's PV input range.

https://cdn.shopify.com/s/files/1/0644/5177/2632/products/03_c458bba3-7854-4de1-846c-51f28a1d4783.jpg?v=1662003353&width=990

 

[LBART]

I guess I am a bit confused here. Why did you use Vmp where the solar calculators I find online use Voc? The one from Victron doesn't make sense to me. It does seem 6 would be better.

Solar panels 200W bifacial JJNSolar
12V 200 Watt Bifacial Solar Panel 10BB Mono High Efficiency Solar Panels

Max Power (Pmax): 200W
Open-Circuit Voltage (Voc): 28.1V
Short-Circuit Current (Isc): 9.12
Optimum Operating Voltage (Vmp): 23.4
Max System Voltage: 600VDC
Max Series Fuse Rating: 15A
Weight 24.9 lbs
Dimensions: 53.7” x 30.3” x 1.4”

From a solar calculator online.
4x 200w Solar Panels wired in a 4s1p

• Solar Array Wattage: 800W
• Temperature Compensated Array Voltage: 141V
• Controller Output Amperage: 14A
• Array Short Circuit Amperage: 9.12A
• Max Series Fuse Rating: 15A

6x 200w Solar Panels wired in a 6s1p

• Solar Array Wattage: 1200W
• Temperature Compensated Array Voltage: 211V
• Controller Output Amperage: 21A
• Array Short Circuit Amperage: 9.12A
• Max Series Fuse Rating: 15A

 

[HarryN]

It is challenging to get more than a solid 1 000 watts from a suitcase size system.

I have built some as well.

Of course for use in WI, AGM batteries are potentially a better choice. Li batteries stored in the garage in WI won't work in the winter.

 

[Shimmy]

I guess I am a bit confused here. Why did you use Vmp where the solar calculators I find online use Voc?

You should use Vmp for the minimum string voltage.

 

[LBART]

You should use Vmp for the minimum string voltage.

So what is the calculation I should use to determine the sizing. And does the Isc matter. The solar calculators use Voc and Isc so are they wrong or is there some correction factor in them?

 

[tim0shel]

May or may not be pertinent to your design process but keep in mind any battery has weight so you'll want a wheeled case.

In my case when I was designing my power station, the first thing I did was lay out all the components and determine the footprint I needed before I went all willy nilly and ordered a case for the system. For me, with two 100 ah cell packs, inverter, charge controller, shunt, etc.., the optimal case was the Seahorse 920SE.

What inverter did you use in there?

 

[LBART]

It is challenging to get more than a solid 1 000 watts from a suitcase size system.

I have built some as well.

Of course for use in WI, AGM batteries are potentially a better choice. Li batteries stored in the garage in WI won't work in the winter.

It won't be stored in a garage. I will keep it in the house. Then I will test some loads to see what I end up with. During a power outage I have 2 full frigerators full of meat, cheese and eggs.

 

[Browse]

Voc is used for max voltage and Vmp for min voltage. You want to use both to make sure your string voltage is within the min and max parameters of your inverter PV input range. Too low a voltage and it won't take solar. Too much voltage and you can damage the unit.

 

[12VoltInstalls]

How much solar would you recommend? I am fine with series or a series/parallel.

You do want some series panels fwiw

How much solar I recommend isn’t answerable without knowing what you intend to power and for how long.

After a recent ice storm left us without power for 44 hrs I knew it was time to do something.

So you need enough batteries for ‘at least’ 36 hours to go one day and two nights with overcast. Minimum.

Go into ‘resources’ and do a power audit on your essential loads… once you know the watthours required then the panels and batteries can be sized.

On my current 800W (~3000W total panels I could connect quickly) I get by with the fridge, coffeemaker, furnace fan, charging devices, etc etc. but most people would be unable to function as well as I do.
Why 3kWh total? Because that might make 1.5kWh on overcast winter days, and be WAY overpaneled for 8mos.+ of the year.

I could wildhat guess at your needs but that’s like randomly buying stocks hoping for a windfall.