Farm Power backup and Future setup

OmahaDZL

New Member
Joined
Nov 22, 2021
Messages
4
Hello all.
I came across Will's Youtube about 6 months ago and Ive been watching and trying to learn as much as possible. Still lots to go. Heres my situation and what I would like to do.

My parents live on a farm in rural Nebraska. I have already purchased a backup 9000w generator from Harbor Freight for those snowstorms that can take the power out for a day or two. I got an amazing deal on it and wasnt really concerned about the fact that it didnt have an inverter at the time. But I am now. Originally I was just looking into a manual transfer switch to power the house. But while looking into that I found Will's page and started wondering about a battery bank....maybe automatic switching....and Ive been wanting solar for our roof forever..... so I kept watching videos and I came up with a plan

Step 1. Backup Generator HF 9000w
Step 2. Inverter with Generator feed (Sol Ark 12k)
Step 3. Server Rack Battery Bank
Step 4. Solar panels on the south facing roof. (is someone making shingles like Tesla or are they the only ones with that design? sounds like they will require a power wall if you want their shingles)

Much of this planned build is due to cash availability and need. For the moment, im thinking of just wiring in the generator and calling it good....and dealing with the fact that its not pure sine. (Heat and lights are better than nothing)

However, after watching David Poz video, I saw that the SolArk is 9k...and that is split between 2 legs. So Im wondering if any of you can help me plan this project out better than what I have come up with so far?

thanks!
 

sunshine_eggo

Happy Breffast!
Joined
Oct 26, 2021
Messages
1,856
Location
USA
Step 0a. Do an energy audit - download spreadsheet in the Resources section.
Step 0b. consult electric bill and estimate your daily kWh use.

Without one of the above, it's like you're saying, "I need a truck to haul stuff," but you're not defining stuff. You might accidentally design a Chevy LUV rather than the Freightliner you might need.

Once you know your daily consumption, you can start sizing the system.

If you have the space, ground mounts are likely much easier and cheaper, and depending on your county's building/electrical code requirements, possibly much easier to make code compliant.

With talking about split phase inverters, it helps to consider current:

9000W / 240V = 37.5A - each LEG of the inverter can supply 37.5A, so you'll have to split your 120VAC loads accordingly. SOME inverters allow for some disparity, i.e., if 37.5A is the limit, but you're pulling nothing on one leg, it might let you go a little higher than 37.5A on the second leg. This will likely be for a short duration and eating into the surge capacity.
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
Joined
Oct 29, 2019
Messages
5,590
Location
Rural NE Ontario Canada
Get out your parents Power Bills for the past year, look at the kWh used in a month and divide by days for that month. You are looking for the power usage during Winter vs Summer. The highest usage is the target if you want to support everything running on the farm. IF this is a dairy farm or other High Energy use Farm that's a different thing altogether... For those unaware, Large Dairy Farm = HUGE Power Use with the coolers, pumps etc... 6 figures within a year people. From your description, it does not sound like a High Load farm... BTW: I was raised on a Dairy Farm.

A few things to ponder (likely have).
1) Connected for Feed-In = Hassles and add 35% on tp of material for permits, certifications etc.
2) Drawing power from grid to charge batteries but not sending to grid, Cheaper, Less Hassle faster ROI.
3) Isolated off-grid system, not an advantage as you have grid power available already
4) Check with your Insurance Company as to any requirements they may require to provide coverage. (too many forget that detail till it's too late)

Now, any typical Farm with have a variety of loads and equipment, 240VAC stuff is petty darn common BUT BE AWARE that most industrial/farm machinery etc are not very efficient, even if electric and older stuff can be downright nasty. Therefore I suggest you stick with 240VAC Split Phase to keep life simple.

Given the type of place and potentials, a 48VDC System is likely the best candidate, 250A @ 48V = 12,000W, 12000W ÷ 240VAC = 50A or two 120V legs at 25A (not corrected for inefficiencies). It is generally recommended not to exceed 250A draw from a battery bank to one inverter. Stacked Inverters can exceed that due to load splitting.

SolArk is costly and beastly but fairly good gear, I would seriously consider looking at the Stackable Growatts, bang for buck damn hard to beat.

Solar Shingles, Tesla is NOT the only player and you cannot DIY Tesla anything ! Just try to buy "parts" not gonna happen. There are HUGE differences using tiles and there is structural math and a heap load more involved with them. The most Cost Effective is a Manually Adjustable Ground Mount system, that allows you to adjust angle for each season which will increase production output across the seasons. Depending on land conditions and a few other things, Bi-Facial panels may be more suitable and deliver even more power per square yard of panel. This also simplifies installation, maintenance and safety (not on a building or anything = less chance of anything going awry) and I believe most Insurance Companies PREFER it not being on a structure.

BTW: We do have completely solar powered farms in my area where the barn roofs are solar covered, biogas generators and a few even have personal wind turbines, a few no longer buy power but only export to grid ! You know, when you have 10,000 litres of milk sour because power went out "again" the line gets drawn pretty fast. 19 outtages up here in 2020 some lasted days.... and THAT is after all sorts of grid upgrades. Hell of a motivator to have solar & battery eh !

After you know the power usages over the different months you will have a better picture of your target. Then you can look at "critical / essentials" that need to operate, like Fridge/Freezer, Furnace Motor, Water Pump, Key Lighting, then you can add Need to have, want to haves and then like to haves. Once identified, get the power usage for the devices, 120V stuff can use a Kill-A-Watt type meter on the wall plug which will give you the amps/watts drawn, there are 240V models too but for "hardwired" things you may be stuck with labels and docs for them to get the specs, worst case scenario a MultiMeter with Clamp Meter can be used to determine Amp Draw. FYI: Many older devices and things like Hot Water "Tanks" are major energy pigs, motors can often be upgraded to "SoftStart" or with variable speed motors which are considerably more efficient. Conservation is ALWAYS cheaper than Generation & Storage.

As a start, I would use 48V 200-300AH modules. In Parallel, you can have different sized packs BUT they should not be too different (capacity wise) else there will be issues & complications. CATCH IS, Buy a Rack Mount Pack today, will you be able to get more later of the same / similar type ? Seriously something to consider ! Racks are great but if a long-term deployment is the plan, then I would look at larger commercial products because of the long-term consistency factor.

Batteries to Inverter/Charger/AIO to 240VAC Subpanel (critical & essential loads) which in turn feeds those circuits. Install the AIO so it draws power from the batteries that are solar charged BUT connected to grid for backup charging of the batteries AND have secondary AC Input from a Genset. No push to grid. Most AIO's have Dual AC Input that can be programmed in different ways, NOT all generators are compatible with an Auto-Gen-Start /Generator Control Start Module.

Hope it helps, Good Luck
 

OmahaDZL

New Member
Joined
Nov 22, 2021
Messages
4
Holy cow! First.... I want to thank you both for the time and energy you have put into your response...I will read and re-read both of them intently.

Second, apologies are due because I didnt specify what kind of farm and the activities that happen there. My parents are retired, very little happens there. Their energy consumption is that of a small/medium sized house. Clothes dryer and oven are the only 240w appliances. 1 fridge and 1 freezer and 1 of the two hot water heaters are electric. And obviously the AC in the summer, however summer isnt my concern for the most part right now, its winter. The furnace is gas. Anyone who knows farms would obviously ask about the water pump....well, thats actually a problem, because its about 100 yards away and is run directly off the power pole.......and Im not about to try to backfeed that thing, so its going to have to remain as is. Anyway... the rest of the farm things you guys are referring to...welders and all that....not a concern.....Im really only looking for emergency power at the moment....long term, really looking for a supplement to the energy usage for the house and sell back to power company. Not really in my plans to size go off grid. The generator alone should be able to handle the things that I want to run in an outage situation (namely furnace, some lights, tv, fridge/freezer). Okay Ill go back to reading your responses now. Thank you again!
 

OmahaDZL

New Member
Joined
Nov 22, 2021
Messages
4
Okay I have reread.... once again, thank you for your time and effort! Its so appreciated to be a newb and to get such great advice. The growwatts are definitely something I will consider.. Honestly one of the main reasons I was looking at the Sol Ark is that it seems to have that grid/solar/generator thing handled in-unit.... I havent seen a video of anyone doing that with a growwatt yet, but maybe thats there and I just dont know it.

As for when I finally do solar.... two things...first you would think that on a farm there would be tons of area to do a ground mount setup, well im not quite set up for that. The house in question has a huge roof that faces south....which is cut into and surrounded by a large grove of trees on all sides except for south...which is our front yard (not going to cover front yard with solar panels). its at least 200 yards in either direction to an open area panels could be set up. I have two other reasons Im interested in solar shingles vs roof mounted panels etc.... First....the heat that gets conducted into the house i would assume has to go down with the airgap in between the solar shingles and the actual roof. I would think this alone would help in lowering costs. Also...we live in an area with a significant amount of hail....asphalt shingles get ruined quite often and I know the Tesla solar shingles have an almost unbelievable warranty... ie.....last time we would have to roof it (at least the south facing side)..... this is why I was asking if Tesla is the only one in the Solar Shingle market....I know they wont allow piece together...but I want to piece this in as I can afford it. So what are other solid options? I just feel like the concept has too many pros to go to old style ground mount....but maybe im wrong there in my assumptions.

I am curious about those private windmills your neighbors have though..... if its one thing we have here, its an abundance of wind, but I was recently told they arent efficient enough to do on a small scale. (I find it hard to believe as the wind blows here more than the sun shines)
 
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