microgrid w/ distributed solar/wind/battery?

Discussion about adding energy storage to grid-dependent inverters using OutBack Power technology
Post Reply
dandenson
Forum Member
Posts: 5
Joined: Wed Jun 02, 2021 6:19 pm

microgrid w/ distributed solar/wind/battery?

Post by dandenson »

I did a quick search but didn't find anything dead-on what I'm wanting to do.

I have an 18 acre property that is long and skinny. like, 3800ft long. We have 4 small cabins on the property. All have good wind exposure and great south sun exposure year round. They are all off-grid running on propane and small generators. I just purchased this property and how the previous owners had things is just so inconvenient and inefficient I can't deal. Power company wants $115,000 to bring power in to the furthest cabin and will NOT allow me to trench in my own line and they have plenty of procedures to make it a hassle for me to do any kind of work-around. No thanks. I can spend that money better.

So, I'd like to build a microgrid. I've talked to a few people that don't have direct advice for what I'm trying to do but they keep saying 'outback!' for more traditional builds. The cabins span about 1/2 the total distance. I'd trench power between each cabin to connect them up. These are meant to be very low energy use and efficient.

The idea here is that each cabin will have solar on the roof. A couple may have some small missouri wind turbines on or very nearby. I'll have a single central generator at the main cabin which is being updated to be a family member's home. two of the cabins will be guest houses and likely be empty half the year or more.

I'd like to do a microgrid with a 230v 'mains' with the frequency set by the main cabin's inverter. The other 3 cabins would have their own, probably smaller, AC coupled inverter/charger w/ a bank of batteries. The PV and Wind would all by AC coupled. Each cabin would have propane primary heat and the water heater would be a dual lp/electric conversion (soft plug swap for a dump load) so I can dump extra wind power (and solar on occasion) into the hot water tank.

The reason I want to microgrid this is that I don't want to spend the money on solar/wind/batteries on the guest houses for it to sit idle while I want/need it at the other two which will have myself on one side and the parents on the other. In essence I just want to distribute the solar generation and I also need batteries at each spot for night time use. Also, I have a really great spot that I want to put a solar array on because just rooftop solar on these small cabins isn't going to cut it. So where I say 4 cabins like there's just 4 sites, it's really a 5th site that is just a generation site and then a small 6th site where I'm putting in a pole to bring internet service in and house a radio and lorawan hotspot for sensors etc.

I just can't tell if the Radian series (or other) really supports this type of build out. I'm also somewhat concerned at how they'll handle voltage drop over the span between cabins. I'm hoping they'll compensate and keep the entire line energized without chewing up batteries on that voltage drop on the lines.

Thoughts? Advice on product? mean words about how I'm dumb for thinking about this? Hit me with what ya got.

I do a lot of tech management for ranches. ie, cameras, water tank and fuel tank monitoring etc. I'd like to get into microgrids with hybrid power so a big part of this is learning at my own property so I can implement elsewhere. I haven't used outback before either. I do a lot of grid-tie stuff or DC-only systems so this is a bit of learning for me adding in the inverter.
raysun
Forum Emperor
Posts: 4835
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: microgrid w/ distributed solar/wind/battery?

Post by raysun »

Some simple-minded advice from an off-gridder with 5 years of uptime representing a long string of 9s to right of the decimal point: KISS.

The AC coupled proposal sounds needlessly complex.

Why not simply put in central power generation and storage, and distribute it conventionally?

Its already planned to have a central fuel powered generator. Why not keep a good thing going, and build a PV array, battery bank, charge controller and invererter complex sufficient to supply the planned power demands? Micro-grid distribution can then be conventional underground wiring and electric sub-panels at each point of use.

Of course, such a system will remove the opportunity for you to enjoy impromptu visits with the occasional guest, in the farthest cabin, at night, in the rain, when something goes wrong with a remote inverter.

For wind power, you're on your own. Everyone I know with wind turbines spends half their time trying to figure out how to effectively manage surplus power generation at inconvenient times, and the other half trying to figure out why there's no power generation at any time. Unless the site is unusually "blessed" with thick cloud cover and steady (but not too strong) winds, turbine generation is easily replaced by more, and far cheaper, PV panels. Putting fuel in the generator is likely to be cheaper in the long run than buying, maintaining, and replacing wind turbines over time.
dandenson
Forum Member
Posts: 5
Joined: Wed Jun 02, 2021 6:19 pm

Re: microgrid w/ distributed solar/wind/battery?

Post by dandenson »

This site is 'blessed' for wind power but that's in my wheelhouse.

I do get your point on keeping everything simple. My biggest issue with a central 'plant' is that I don't have enough room to do that with a single PV array without sacrificing a lot aesthetically and cutting down trees. This is a ridgeline so I want to avoid removing even a single tree because that's the wind break. There really is only one spot that is on a south facing slope that I could get a few KW in without cutting trees. Additionally, I'd really like to have power down the entire line so I can put in some driveway lights and security cameras. That doesn't really exclude your advice to have a central 'plant' though.
Mike Curran
Forum Emperor
Posts: 2308
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: microgrid w/ distributed solar/wind/battery?

Post by Mike Curran »

I like the idea of a grid-tie inverter at each cabin, AC-coupled to your central inverter, because each cabin's output can contribute to the others' loads when needed. It can get expensive compared to Raysun's preferred setup since you'd need a charge controller, batteries and inverter at each cabin. But if you must install PV on each cabin to get the power needed, then that might be your only solution.
https://smart.tigoenergy.com/p/pZXn7SZQyO45?date=2021-04-19
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
raysun
Forum Emperor
Posts: 4835
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: microgrid w/ distributed solar/wind/battery?

Post by raysun »

I'd look at distributing PV arrays wherever they'd fit, and using Outback FM100 AFCI charge controllers. They are designed to handle 300V strings, so can support fairly long home runs without excessive loss.

In the original concept of having PV on every rooftop, it would involve running DC down to the central plant, and AC back, which seems like a waste of copper, but the economies of equipment cost (and service) having the "guts" centrally located is worth a pencil exercise at the very least.

I'm not familiar with the intimate details of AC coupling, but most of what I've seen relies on the Grid providing sync. There are some AC coupled devices that can work without the presence of the grid, AFIK, and if they can be synced with a "primary" inverter, then they may be able contribute to charging a central battery. ("Selling" to the loads, as opposed to selling to the grid.) I seem to recall some discussion on this forum about that architecture using Radian inverters, but didn't study it as I have no application for it.

The notion of maintaining 4 separate battery systems gives me the willies, TBH. I fear it would seriously cut into my beer drinking time.
Mike Curran
Forum Emperor
Posts: 2308
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: microgrid w/ distributed solar/wind/battery?

Post by Mike Curran »

most of what I've seen relies on the Grid providing sync.
The Radian AC output simulates a grid. When/if the Radian-grid goes down, any AC-coupled inverters go into battery backup mode to support their individual loads.
In the original concept of having PV on every rooftop, it would involve running DC down to the central plant, and AC back, which seems like a waste of copper,
The original idea was to have semi-independent systems at each cabin with only AC wiring between them, IIUC:
I'd like to do a microgrid with a 230v 'mains' with the frequency set by the main cabin's inverter. The other 3 cabins would have their own, probably smaller, AC coupled inverter/charger w/ a bank of batteries. 
Edit:
The notion of maintaining 4 separate battery systems gives me the willies, TBH. I fear it would seriously cut into my beer drinking time.
I have 2 separate battery systems and my drinking time hasn't been affected; if anything it causes me to drink more :grin:
https://smart.tigoenergy.com/p/pZXn7SZQyO45?date=2021-04-19
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
raysun
Forum Emperor
Posts: 4835
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: microgrid w/ distributed solar/wind/battery?

Post by raysun »

I have 2 separate battery systems and my drinking time hasn't been affected; if anything it causes me to drink more :grin:
Then there is that! 😆
dandenson
Forum Member
Posts: 5
Joined: Wed Jun 02, 2021 6:19 pm

Re: microgrid w/ distributed solar/wind/battery?

Post by dandenson »

raysun wrote: Thu Jun 03, 2021 2:35 pm
I have 2 separate battery systems and my drinking time hasn't been affected; if anything it causes me to drink more :grin:
Then there is that! 😆
I'm considering an AC Coupled Li unit. Not the powerwall, but similar. Those are maintenance free and warrantied for 10 years/5k charge cycles. I've penciled this out and it's barely a premium because I wouldn't have to replace a battery out of pocket for ~10 years.
raysun
Forum Emperor
Posts: 4835
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: microgrid w/ distributed solar/wind/battery?

Post by raysun »

Lithium batteries do simplify the maintenance equation. We are all hoping that long life is more than marketing.

🤞
dandenson
Forum Member
Posts: 5
Joined: Wed Jun 02, 2021 6:19 pm

Re: microgrid w/ distributed solar/wind/battery?

Post by dandenson »

raysun wrote: Thu Jun 03, 2021 3:02 pm Lithium batteries do simplify the maintenance equation. We are all hoping that long life is more than marketing.

🤞
Well that's what warranties are for :). Gotta buy from a brand that's likely to survive for the 10 years though, that's the trick.

I have 2 wISP sites I run on home-made 18650 battery banks that are now about 2 years only and holding strong so I'm optimistic.
sbrownian
Forum Czar
Posts: 562
Joined: Mon Nov 30, 2020 9:23 am
My RE system: GS8048 FM80 FNDC Mate3
4kw solar
7kw Kubota propane gen
Had 1200 Ahr FLA Locomotive batts
Just replaced with
2 x 300 Ah ReLion Lithium packs
MUCH more efficient!!
Location: Central Washington State

Re: microgrid w/ distributed solar/wind/battery?

Post by sbrownian »

Without seeing load requirements at each cabin, is 230v going to be high enough to use as a 'distribution' voltage? (I sqr R losses..)

Would kicking it up to 480 (or higher,) offset the cost of the cost of larger conductors?

Adding 'drop' transformers would also add a measure of isolation, and since you mentioned 'ridgeline,' what's the lightning situation like?
Information, you get not; if incorrect question, you ask..
dandenson
Forum Member
Posts: 5
Joined: Wed Jun 02, 2021 6:19 pm

Re: microgrid w/ distributed solar/wind/battery?

Post by dandenson »

sbrownian wrote: Mon Jun 07, 2021 5:47 pm Without seeing load requirements at each cabin, is 230v going to be high enough to use as a 'distribution' voltage? (I sqr R losses..)

Would kicking it up to 480 (or higher,) offset the cost of the cost of larger conductors?

Adding 'drop' transformers would also add a measure of isolation, and since you mentioned 'ridgeline,' what's the lightning situation like?
230v is interesting because of standard micro-inverters for panels. I love the idea of getting the volts up to offset smaller feeder lines but I don't think it's viable.

No substantial lightning issues. There are taller ridgelines on both sides plus there are high spots on the ridge that I'll likely put lightning rods.
Post Reply