Planning off-grid workshop/home in northern Wisconsin

[DillyFPV]

Hello everyone,

I recently purchased 40 acres near lake superior in WI, and I would like to build a sort of barn/workshop/home situation. Power lines are a mile away so I'm obviously going off-grid, which I'm happy about! Use in the coldest winter months when solar energy is at its weakest may be limited because I generally travel south. I have built several smaller (sub 1kw) systems for campervans and travel trailers and I plan to build this new system myself, but my knowledge of these systems is fairly basic.

It would be pretty straight forward if it weren't for the "workshop" aspect of my plans. I would like to be able to run welders, grinders, air compressor, drill press, table saw, well pump, etc, and hopefully even a hydraulic two post lift. Bear in mind, this equipment won't be used all day every day, just sporadic, hobbyist use. A generator to supplement power during heavy loads and cloudy days is probably going to be a thing. My budget for the solar system is $10-20k. Am I out of my mind, or is this in the realm of possibility?

I have barely scratched the surface with my research and planning, but so far my assumptions are that I will be running a 240v inverter, 48v battery bank, and 5kw+ PV on tilt-able mounts. Not sure if lithium or lead acid, I do like the idea of a used electric car battery bank. I'm also interested in running a generator on wood gas eventually, but that's for a different forum.

I'm hoping you folks can help me determine if this is even realistic within my budget, and if it is, help me start to plan a system that will meet these needs. (or most of them)

Thanks,
Dylan

P.S. Here's a photo of my current home (self built ambulance rv 4x4 conversion, more or less what I will be building in this workshop) with 300w on the roof, 300ah AGM, and a 1500w inverter. It runs a little 12v fridge, led lighting, water pump, device charging etc. Its a little overkill for my consumption and I rarely have to charge from the alternator.

 

[snoobler]

Welcome to the forum.

Cool home.

Keys to designing a successful system: 1) solar availability and 2) daily energy needs.

1) Link #5 in my signature
2) Link #1 in my signature

Lots of homework involved. Do it, and you'll have a good basis for a successful design. Skip it or take too many shortcuts and you either 1) don't have a system that works for you, 2) spend too much, 3) get lucky.

Planning defeats #1, helps you avoid #2 and makes #3 unnecessary.

When determining what you want to power, pay special attention to surge currents (inrush current, locked rotor amps) of any items with an electric motor. Their run time power/current may be very manageable, but their surge may be 3-7X their run, and that can cause an inverter (particularly the popular cheap ones) to overload and shut down leaving you angry and bitter.

Once you have it defined, it's just a matter of selecting components.

Good luck!

 

[AlaskanNoob]

I don't have the experience to help you out, but I'm interested in the discussion. We are doing something similar although we don't have the power requirements you have (at least I don't think). We are hoping to run a freeze dryer in the summer that uses something like 14KW of energy in 28 hours or so to process a single batch of food.

Since you have lots of acres and since panel cost is somewhat cheap, perhaps the money toward a tilt/pan system might be better spent on dedicated winter panels? I don't know much about tilt pan systems but I've heard they're pricey and in the snow you might have issues with them. Just stuff I've read, I have no experience to back it up so I could be completely wrong.

 

[OffGridEnclave]

its doable..
there is a few BUT's ...
- serious offgrid requires a lot thought on overall desing and redundancy
- welding is VERY bad on batteries, would reccomend getting a proper size generator for that,
most other power tools are doable on batteries
- You need some idear how the situation at your location is.
a lot of the "knowledge by theory people" will tell you " HERP DERP U MUST DO 6 PAGES OF MATH" ,
nja it will help to give an idea, BUT reality is you need to adjust your life to the system you have
as well as adjust the system for your life. I never did any math for my powerusage and i am offgrid since 7 years in 3600ft² structure.
This depends a lot on you location, "math" will only ever give a vage idear.
you WILL need to overdesign the system in terms of powerinput , desing for the bad times of year not the good ones..
(if you rely on having 500W input at bad weather you might need to throw out 6-8kw in panels)
( Sun is up -> can run powertools and hairdryer, shitweather and clouds -> no powertools )
- you budget is realistic if you are carefull on the spending side.
- for redundandency of the system or genset ( woodgas, biogas, selfproduced diesel,windgen,hydropower, sterling engine, TEG, etc. )-> SPEAK WITH PEOPLE WHO LIVE OFFGRID, there is a bazillion options.

ref: my "casual" solar system

-> https://offgridenclave.com/2021/02/15/advanced-offgrid-powersystems/

feel free to pop on our discord for offgrid related questions/talk.
(solar is a small tiny part of beeing offgrid, much more to it)

Tritt dem OffGridEnclave-Discord-Server bei!

OffGridEnclave is a hub for information, technology, human skill and culture around living self sufficient. | 1043 Mitglieder

discord.com

 

[DillyFPV]

Thanks for the replies.

Offgridenclave, I agree with your approach, I'm not huge into planning (or over planning) to be honest, haha. I suppose my plan is to build biggest/best system that I can afford, and then adjust/supplement my power consumption to conform to what that system is capable of. I do however want to verify that the more power hungry tools will not overwhelm the system, but its not always easy to find the start up amps especially if I don't even own the tool yet.

The possibility of having to get a diesel welder generator IF my system can't cope with welding is fine, so the system doesn't necessarily have to support welding. if it does, cool, bonus.

It looks like I can afford a pretty decent 5000w-ish inverter charger which would have around a 10000w peak rating. As for panels, I can probably afford 4-6kw. I haven't really gotten an idea of what size battery bank is going to be appropriate. Do you guys think that an inverter that size would handle starting up a large 240v air compressor? And what's this I hear about modifying electric motored tool to "soft start"?

 

[snoobler]

Thanks for the replies.

Offgridenclave, I agree with your approach, I'm not huge into planning (or over planning) to be honest, haha. I suppose my plan is to build biggest/best system that I can afford, and then adjust/supplement my power consumption to conform to what that system is capable of. I do however want to verify that the more power hungry tools will not overwhelm the system, but its not always easy to find the start up amps especially if I don't even own the tool yet.

The possibility of having to get a diesel welder generator IF my system can't cope with welding is fine, so the system doesn't necessarily have to support welding. if it does, cool, bonus.

It looks like I can afford a pretty decent 5000w-ish inverter charger which would have around a 10000w peak rating. As for panels, I can probably afford 4-6kw. I haven't really gotten an idea of what size battery bank is going to be appropriate. Do you guys think that an inverter that size would handle starting up a large 240v air compressor? And what's this I hear about modifying electric motored tool to "soft start"?

The necessary planning is pretty trivial. The hard part is getting the details on the items, such as surge. One can do a complete top-level energy audit and solar availability analysis in less than an hour.

FWIW, my puny little 120VAC welder runs great on my Victron Quattro 5kW. It barely notices it.

Additionally, be vary wary of peak ratings. Get the details. Most high frequency inverters list a 2X surge, but the duration they can maintain is typically measured in milliseconds. Some claim for up to 5 seconds, but I won't believe it until I see it. The heavy low frequency inverters with massive transformers are the only ones that have a truly robust surge rating.

 

[DillyFPV]

FWIW, my puny little 120VAC welder runs great on my Victron Quattro 5kW. It barely notices it.

this is good to know.

 

[snoobler]

this is good to know.

Also worth noting that Victron is stupid expensive, and this unit has a 10kW legit surge.

 

[DillyFPV]

Also worth noting that Victron is stupid expensive, and this unit has a 10kW legit surge.

$2500, thats fine. Back of the napkin math suggests that a system with that sized/priced is within my budget. I've been eyeing the magnum MS-4448PAE which is comparable in price and specs. you can get it pre-wired with a charge controller and the whole shebang for like $5k. What do you think of those? I like the idea of a pre-wired system, just add panels and batt bank. It reduces the amount of time and effort that I have to put into this.

 

[OffGridEnclave]

The heavy low frequency inverters with massive transformers are the only ones that have a truly robust surge rating.

Can defently confirm that..
I use two High fequency 2.4Kw Inverters they usually tilt after ~0.3 sec surgecharge, and one low fequency 3.6Kw (that can surge to like 7Kw for 10 minutes according to manual) for heavy tools.
this is what i run my bunker on:

8400 Watt Solar Panels
400 Watt Wind Generator
3x Deep Cycle Batteries at 24V : 1150 AH c5, 740 AH c5, 720 AH c5
2x High Frequency Inverters 2,4 Kw
1x Low Frequency Inverter 3,6 Kw
3,6 Kw Gasoline Generator Multiphase 220/400 Volt
3,2 Kw Gasoline Generator Singlephase 220 Volt

 

[DillyFPV]

I use two High fequency 2.4Kw Inverters they usually tilt after ~0.3 sec surgecharge, and one low fequency 3.6Kw (that can surge to like 7Kw for 10 minutes according to manual) for heavy tools.

Wow, that's quite a bit of inverter(at least compared to what I was thinking). What sort of tools are you running?

 

[snoobler]

$2500, thats fine. Back of the napkin math suggests that a system with that sized/priced is within my budget. I've been eyeing the magnum MS-4448PAE which is comparable in price and specs. you can get it pre-wired with a charge controller and the whole shebang for like $5k. What do you think of those? I like the idea of a pre-wired system, just add panels and batt bank. It reduces the amount of time and effort that I have to put into this.

I have a long distance love affair with that inverter. Had I not already been hooked to Victron, that's choice #2. My neighbor has the MS4024PAE and is going to replace his old Trace SW4024 to get split phase to the house.

 

[snoobler]

Can defently confirm that..
I use two High fequency 2.4Kw Inverters they usually tilt after ~0.3 sec surgecharge, and one low fequency 3.6Kw (that can surge to like 7Kw for 10 minutes according to manual) for heavy tools.
this is what i run my bunker on:

8400 Watt Solar Panels
400 Watt Wind Generator
3x Deep Cycle Batteries at 24V : 1150 AH c5, 740 AH c5, 720 AH c5
2x High Frequency Inverters 2,4 Kw
1x Low Frequency Inverter 3,6 Kw
3,6 Kw Gasoline Generator Multiphase 220/400 Volt
3,2 Kw Gasoline Generator Singlephase 220 Volt

Just checked out your bunker site. Very nice. We're at our infancy... 39 acres, 40' shipping container and a couple of RVs for living space (system specs in signature). Plan to be as reasonably self-sufficient as possible on all electric. Rain catchment to start and likely a well, but our wells are > 200m deep here.

 

[OffGridEnclave]

Wow, that's quite a bit of inverter(at least compared to what I was thinking). What sort of tools are you running?

full construction site...
angle grinders, presshure hammers, drills, concrete mixers, saws, etc..
that aside a "normal" household, computer, washing mashine, dish washer, etc.

 

[Hedges]

If you bought a DC Solar trailer, that would probably provide 100% of your needs except for having only 2400W of PV panels.
These have two Sunny Island, two forklift batteries (make sure these are healthy), one Midnight SCC, 2400W PV.
Diesel generator is included on some.
People bought these for some lower price at the bankruptcy auctions and are reselling them on eBay and Craigslist.
Typical asking price without generator seems to be $10k. With your $20k budget should be able to get one with generator and expand PV (e.g. add 5kW panels and one Sunny Boy.)

 

[DillyFPV]

full construction site...
angle grinders, presshure hammers, drills, concrete mixers, saws, etc..
that aside a "normal" household, computer, washing mashine, dish washer, etc.

Nice, thats what I'm talking about. Looks like you have 8kw of pv, and 2500ah 24v with those inverters. This system would probably stretch my budget pretty good, maybe not tho. Is it pretty adequate for your needs? what would you improve?

Hedges, I saw one of these rolling down the street the other day and wondered what the hell it was, now I know! Kind of a cool setup, although maybe a bit of a waste to have to buy the trailer.

 

[Hedges]

Buy the PV system, get the trailer for free.
Saves on shipping cost anyway.

MSRP:
SI-6048 $5000
SI-6048 $5000
GNB forklift battery $5000
GNB forklift battery $5000
Midnight Classic SCC $700
2400W PV $1200

(There are a bunch of those SI-6048 being sold around $2000 +/- due to same DC Solar bankruptcy)
Diesel generator would be a big plus for your complete system.
The one I see on eBay right now isn't the bargain price I would hope for, would rather it was $15k or less

12KW SOLAR KUBOTA DIESEL GENERATOR TRAILER BATTERIES PURE SINE INVERTER MILITARY | eBay

•Continuous 12kW. A complete plug and play all in one solar energy system with huge battery storage and 11kw automatic 110 Gal Kubota Diesel backup generator at a fraction of the original wholesale price.

www.ebay.com

This one without generator and only one battery, asking $14k

SOLAR TRAILER GENERATOR with 20Kw battery - general for sale - by...

SOLAR TRAILER 2.3kw solar panels GENERATOR with 20kw battery Only $13,800 OBO DC Solar MSG (mobile solar generator) with GNB Flooded Classic Platinum industrial batteries 468 AH capacity 48 volt,...

sfbay.craigslist.org

At those prices it would be cheaper to assemble your own. If you can buy right, then get a trailer.
I use SMA for my grid-backup system and recommend it. Famous for quality and ability to start motor loads. (some other brands are good too.)
With two Sunny Island (11.5 kW) you can add up to 24 kW of AC coupled PV, good for larger daytime loads.

 

[DillyFPV]

Those are pretty cool, and the generator would be nice, although I think I'd almost prefer a cheaper gas generator for its ability to run on wood gas in the future. it would be great to have a stand alone system while I'm building the barn. my plan was to temporarily install my system on a 20ft container until my building is done and I can re-install inside. 25k is high though. those inverters are 3400 each, and who knows what you are getting when you buy 5 year old used lead acid batts.

I'd really love to see some detailed schematics of systems in this size range. I'm curious about you combine outputs from several different inverters. Is it as simple as running all the outputs to the same breaker box? How about combining power from your solar system and a generator for heavy loads? How about charging dis-similar batteries if you've cobbled your bank together over time? Individual chargers for that? I personally learn visually, a picture is worth a thousand words, ya know?

And with all the cheap lithium batts coming out of china and other places, is that starting to be a more cost efficient option than lead acid? how about safety? I build and fly racing drones that use 5 and 6s lipos, and those things literally turn into a F-ing blowtorch when they have a thermal runaway. I've seen some people build some massive 18650 packs, and those can get pretty nasty when they fail too...

 

[Hedges]

DIY LiFePO4 is now cheaper per kWh of gross capacity than the AGM I use, so certainly can be a more cost-efficient option with their greater cycle life.
Although, if a forklift battery is sized for multiple days without sun, people report 15 years life so may be equally cost-effective at this time.
We know that long LA life requires proper care and feeding, which sufficient PV capacity and a charger with good algorithms can achieve.
Certainly non-explody LiFePO4 is looking like a viable option.
Future building codes will apparently require UL listed battery systems (if not lead acid) but will allow repurposed EV batteries in a shed at least 5' from the house.


These brochures have block diagrams rather than detailed schematics:

https://files.sma.de/downloads/SI6048US-DS-en-27.pdf?_ga=2.170075232.1149189979.1614212349-621369231.1589916091

https://files.sma.de/downloads/SISYSGUIDE-KEN140421.pdf?_ga=2.170075232.1149189979.1614212349-621369231.1589916091

Up to four Sunny Island can be connected in parallel 4p (120V) or series/parallel 2s2p (120/240V), or three for 120/208Y.
I think SI-5048, SI-4548, SI-6048 can be mix and match so long as all on a single phase are same model.
An RJ45 cable daisy chains them to synchronize timing and coordinate battery charging.

Multiple Sunny Island can land on a breaker panel, paralleling those assigned to the same phase.
A generator could feed a single Sunny Island input (in which case it would pass through and the others make up the missing phases) or multiple phases.
One issue I had with grid feeding through 2s2p configuration was paralleled paths didn't split current evenly. Problem was QO270 breakers, which had differing resistance. I replaced with Schneider 63A DIN mount breakers outside the panel and that problem went away.
If load exceeds what you've set for maximum AC input (up to 56A), then Sunny Island draws from battery to supply the additional current.

All these Sunny Island in a single "cluster" use a single battery bank, should be same age at least if lead-acid. (A village could have multiple interconnected clusters.)
Supported batteries are FLA/AGM/Gel, NiCd, Lithium (with compatible BMS such as from REC to communicate).

PV can be DC coupled. Either a battery shunt informs Sunny Island of charge/discharge current, or if SCC is Midnight Classic a data interface is available.
AC coupled PV is preferred. Either Sunny Boy or any GT inverter that supports Rule 21 Frequency/Watts. They just land on the same breaker panel as Sunny Island. Their output power is commanded to reduce if required by raising frequency towards 62 Hz. AC coupled PV up to 2x the wattage of Sunny Islands.

It is recommended to have a load-shed relay, allowing Sunny Island to disconnect all non-critical loads in case of low battery. That way it can still make AC for the AC coupled PV to work when sun comes up

My system has excess PV, backfeeds the grid and then use electric heat in the winter. Off-grid, battery stays full during the day and loads like A/C run direct off PV. At night my battery drains toward 70% by morning. Of course I use gas not electric heat if grid is down.


Victron offers similar stacking ability for their inverters for single/split/three phase, as do some less expensive brands.

 

[Hedges]

25k is high though. those inverters are 3400 each, and who knows what you are getting when you buy 5 year old used lead acid batts.

Agreed.

Saw some more posting that aren't out of line in terms of price.
As for condition of batteries, considering these were built with PV panels and mostly unused, there is a reasonable chance they were kept at a good float voltage. Maybe never watered, but I don't know how necessary that is without extensive charging. Some have been described as batteries dry which indicates something happened.

What I see offered at this time:
With two batteries, buy it now $10k or offer
With one battery, starting bid $7.6k
With bad battery, starting bid $7k

If you were just going to hang inverters on your wall, they are available for $2000 each from some sellers.
If the battery is good (some people here have bought the trailers and everything works, but don't know remaining battery capacity), then the turn-key package is a decent deal if they can be bought for these prices.

Solar Generator with batteries on trailer - grid-tie or off-grid, 2.5kW | eBay

Great for cabin use or anywhere you have ground space available. 10 - Solar Panels. The panels are either Talesun or Boviet Solar. Both are 250W/panel, so maximum 2.5kW per trailer, DC. If desired, we will unmount solar array from trailer, and remove trailer.

www.ebay.com

Mobile Solar Powered Generator Trailer | eBay

Find many great new & used options and get the best deals for Mobile Solar Powered Generator Trailer at the best online prices at eBay! Free shipping for many products!

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Mobile Solar Powered Generator Trailer BATTERIES MAY BE DEAD - DISCOUNTED | eBay

Find many great new & used options and get the best deals for Mobile Solar Powered Generator Trailer BATTERIES MAY BE DEAD - DISCOUNTED at the best online prices at eBay! Free shipping for many products!

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The way DC Solar assembled these in a close-fitting box doesn't give as much ventilation as inverter manual calls for. Would be good to improve that.