[NayuluTjuta]

Some months ago, I mentioned in another post that we were planning to go off grid.  Well, we’re there, but still paying daily supply charge, although we aren’t using any grid power.  The final switch over happened on 8th Dec 2017.

Research and planning has been going on for about 18 months.  Retirement has given me heaps of time to glean information and look at alternatives that could use the solar panels we already had on the roof plus allow me to do most of the design, build and implementation plus be in control of the system on a daily basis.

As an intro, here’s a few technical details:
Solar Panels:  19 x 240watt (another 3 x 240watt plus 5 x 275watt to be added soon, then 12 x 275watt within 12 months)
Battery Storage: 24 x 300ah LiFePO4 cells arranged to give 900ah @ 25.6v.  That’s 23kWh of energy storage with 18kWh usable before system shutdown to protect the battery bank.
BMS (Battery Management System):  SBMS120 (ElectroDacus)
Inverters: 3 x Victron Phoenix 3000VA (Working in Parallel).
Heating: Using a device still to be supplied and configured.  An additional device will manage the solar panels so that excess solar energy not required to keep batteries charged and run the inverters will be diverted to heat water.  In addition to heating hot water for general use, approximately 28kWh of heat energy will be stored and used to heat the home using hydronic heating panels in winter.  Additional heat storage capacity can be added if required.

That’s it in a nutshell.  I’ll add some images later.

Bob

[Dazzler]

Very interesting Bob. Nice to hear from you. I'd love to do something like that but how much are we taking roughly?

[beerman]

I reckon its not going to be cheap 

[mickd]

The way electricity is going up,  won't take long to re-coop

[NayuluTjuta]

I reckon its not going to be cheap 

@Dazzler, @beerman is correct.  Having said that, the biggest expense has been the Winston LiFePO4 cells.  The price of panels has come down (and I had 22 of them anyway).  Every indication is that, if properly managed, the battery bank has a similar life to solar panels.

I’ve allowed a budget of $27k, but that includes a laundry upgrade and passive heating system and one other component I haven’t mentioned: a separate solar submersible water pumping system for our bore.  No utility bills for this rubber ducky.

The bore wasn’t planned, but the existing 19 yo pump happened to give up the ghost leading up to Xmas (Murphy was at it again).

Bob

[NayuluTjuta]

[beerman]

Do you have any backup? or if it runs out your left in the dark again.....

[NayuluTjuta]

Do you have any backup? or if it runs out your left in the dark again.....

At the moment, we’re still pay daily grid connection charge.  If we need, we have a change over switch in our main house board that allows us to isolate either the grid or the inverter feed.  We haven’t had to use the grid since the first switch over. 

One option we’ve considered if we terminate the grid connection is to install a socket for a generator for emergency power. The change over switch will be reworked for this.

We’re also currently running all cooking appliances from our battery/inverter power.  We’ve got a gas cooktop to replace our current electric cooktop which will reduce our load on the battery/inverters.


Bob

[beerman]

Nice.

Is this something you are doing because you can, or is the project expected to pay its way?

It is something I will look at in 2022 when my super duper feed in tarif is no more and the cheques that are my power bill stop coming.

[Lakes]

impressive bob well done.

two years back a friend moved from the coast to a 70h a farm. they have two teenagers, that use a lot of power.
he payed for a system with guarantee & based on they power usage cost him 25k. that was two years back and to date no problem's they don't have power hooked up now. at start they kept it hooked up in case & payed $70 per year just to have it if needed. saving 6
$3.5k per year on power bill they had two years back.

[NayuluTjuta]

Nice.

Is this something you are doing because you can, or is the project expected to pay its way?

It is something I will look at in 2022 when my super duper feed in tarif is no more and the cheques that are my power bill stop coming.

A little bit of all of the above.  Having recently retired (3 years ago now), I wanted to challenge myself and keep my mind active.  It’s difficult to determine the expected payback with power prices on the rise in Australia. 

Like you, @beerman, we hadn’t had a power bill for a number of years.  Once the input tarrif went down to 6c, we saw our credit slowly dwindle away.  Received our first bill of around $100 just before Xmas. 

We have an interesting power setup with 3 tarrifs. There’s our domestic tarrif, our hot water tarrif and a completely separate rural tarrif (that’s connected to our shed and also ran our old bore submersible pump).  The latter is cheaper than domestic and has a lower tarrif during the night (similar to a hot water tarrif).

I’ve done all the rewiring of solar feeds myself, changing the parallel high voltage low amperage setup to parallel low voltage high amperage.  This was required for the BMS I’m using.  Basically I have done all the DC side of my setup (all less than 35v) up to and including the DC to the Inverters.  The AC out of the Inverters plus all AC connections to the Main Switchboard has been done by an qualified electrician.

Bob

[NayuluTjuta]

@Lakes, having teenagers at home certainly does put power usage at another level.  We’re empty nesters now and have really noticed the drop in power demand.  We were at a daily average of 18-19kW a day with four of us.  That’s now down to 8-9kW a day.

Some of this can be put down to smarter use of power with Using LED lighting, some of it run from 12v connected to lead acid batteries charged by 3 x solar panels.  This system also runs my NBN equipment, allows us to charge phones, tablets, etc. and weather station server.  In the past, this has meant we weren’t in the dark and still had a NBN when there was a power failure.

One of the funniest things that happened when I first began laying out my plans to Sue (wife).  We were out having an evening meal and I was explain some of the details of what I had in mind.  Next thing she went into hysterical uncontrollable laughter and couldn’t stop.  The more I explained, the worse she became.  She shared more idea with our daughters (via texts) and it just added to the situation.  At least she didn’t throw anything at me.

Bob

[NayuluTjuta]

One cool feature of the BMS I’m using is the ability to monitor what’s going on by connecting to the BMS with any WiFi compatible device (I’m using iPad or iPhone) that can store and display a HTML page. 

[Dazzler]

I'll try again. I did a post a few hours ago which got lost. I got kicked off!   

You've done a great job Bob. So impressed. Maybe one day I can see it in person.

Being tight, when we lose our 28c fit at the end of this year I think, I reckon I'll just go 4 more 250 watt panels to take us to 4.8 kw with 5 kw inverter at a cost of about $1500 installed and maybe a small wind turbine just for novelty factor at another  $1500 or so. We have 2 x hot water cylinders, one solarand one grid. I'll probably decommission the grid one at just a few $100 to reroute some plumbing. 

[NayuluTjuta]

@Dazzler, if you happen to be in SA, you’re welcome to have a 👀.  The system is based on that being used by the designer and builder of the equipment I’ve sourced (via Kickstarter).  He’s a Canadian (Dacian Todea), an electrical Engineer.  He’s totally off grid and lives in the Tundra.  I’ve picked the eyes out of what he’s doing that suit my situation.  He’s been so helpful, often responding to my emails within 10-30 minutes with adjustments and settings within his software to solve issues I’ve had.

Because I decided to use his equipment it really forced me off grid.  The system has bedded in well since New Year after a few adjustments.  We spent a good deal of time away in Melbourne a week ago shifting one of our daughters furniture and came home with e erything running smoothly.

While in Melbourne I picked up 2 x hydronic heating panels (1300mm x 600mm).  While they common or heating in the Eastern states, they’re scarcely used in SA. 

Prices of solar panels are coming down all the time.  Last 5 I bought are 275watt and cost me $220 each.   I hoping they may be less when I need the next 12, making a total of 39 panels.

I’ve still got my 5kW grid tie Inverter (SMA Sunny Boy). Hopefully the local electrician will take it off my hands in exchange for a few more alterations I need done.

A few locals are starting to ask for my advice.  I’m not going to advise them to follow my example.  I’ll explain what I’ve done, point them to commercially available options, but not get involved further than that.

My system is really a large version of what you might find on a big yacht, houseboat or motorhome.

I’d say your thinking around what to do in the future is sound.  Off grid storage may well come into your considerations by the time you make a decision.  There are domestic installations in SA that have battery storage.  While not large, they mean those who have e them can use the storage at night.  They get financial assistance for the installation on the condition that, should a the grid need backup (as it did the other day when a Vic coal fired power station failed), the grid is able to draw on their storage.  They get compensated for what they supply back to the grid at very good rates.  Interesting idea.

Bob

[Dazzler]

Wise not to get too involved with other's choices.  I've led a few of my friends to water, but I don't make them drink unless they want to. If things don't meet their expectations it can get awkward otherwise. 

[technomadness]

I’m interested in the ElectroDacus.  I’m confused about the load output, though.  It seems you’re using three Victron 3kva in parallel, which could pull 9kva from that load— is that how it’s set up?

And is this so the solarBMS can keep track of how much AH is remaining in the battery?

At 24v that’s up to 375 amps, which seems a lot to pull thru that tiny device.

I must be missing something.


Sent from my iPhone using Tapatalk

[Dazzler]

I'll tag Bob. @NayuluTjuta he hasn't been on for a while.

[NayuluTjuta]

I’m interested in the ElectroDacus.  I’m confused about the load output, though.  It seems you’re using three Victron 3kva in parallel, which could pull 9kva from that load— is that how it’s set up?

And is this so the solarBMS can keep track of how much AH is remaining in the battery?

At 24v that’s up to 375 amps, which seems a lot to pull thru that tiny device.

I must be missing something.

I doubt I’ll ever pull 9kVA as my loads would never be that high.  Each inverter will support around 10amps (2400w) constant load and I was looking at being able to support 30amps (7200w) constant load maximum in my planning.

The SBMS120 will not support more than 120amps through put via its Load + terminal, but can accomodate 500amps through an external shunt, so the 375amps you mentioned would pass from the battery through the shunt.  In turn, to track capacity, the shunt passes the current flow to the SBMS120 via a CAT5 twisted pair.

Hope that makes sense.

To date, the current consumed by the inverters has not exceeded 215amps.

Further Update

We’ve been successfully Off Grid now since the beginning of Dec 2017, so a total of 4 months now.  Other than a few cloudy days, the battery is back to full capacity by early afternoon without having to switch in all available solar capacity.   Even on the occasions where we’ve had successive cloudy days, we’re back to around 80% capacity by dusk which doesn’t put us at risk of draining the battery overnight.

Bob

[Dazzler]

Thanks for the update Bob. Hope you are keeping well.