Backup down under

[wattmatters]

An update. While the clone PIP4048HS inverter has been terrific and shown I can make an off-grid system work with great functionality and complement our grid-tied PV system, I've decided it's now time to upgrade to something a little more powerful.

Since adding the server rack LiFePO4 batteries I've been running the house from this little PIP unit for a couple of months and it's been great. Before that it's been in operation for well over a year doing duty running the pool pump and keeping our backup reserve of lead acid batteries ready for outage backup. It's kept us going through numerous outages.

Since running the house with it we would occasionally experience overloads in the evening, and while the little PIP clone handles that well by instantly switching over to Utility pass through mode, I'd rather it didn't need to do that. I really don't want to be paranoid about every time the wife wants to make some hot tea while she has the microwave going for something else. Plus we have a second occupied dwelling as well which might be doing something similar.

So I have picked up an EASun 8kW SMA MAX unit. The is the same unit as the MPP Solar PIP 8048 MAX.

Today's job was mounting the unit to the brick wall.



The little box underneath the inverter is my pool robot controller. That will be relocated as I will have cables/conduit and relevant breakers needing that bit of wall real estate.

Mounting the inverter was a bit challenging so to make it easier I went with a French cleat type of solution using two aluminium Z-brackets. I considered using a mounting backboard but didn't think it would look as nice, so I gave the Z-bracket a go.

I mounted one bracket to the wall using 4 x 8mm masonry wall plugs and screws. The side on shot shows how the Z-bracket leaves a slot for the other bracket to slide in to. I had to shim a couple of the screws behind the bracket because of the unevenness of the brick - this kept the bracket straight.



The other Z bracket is affixed to the mounting rail at the top of the inverter, with mushroom head bolts, nuts and washers.



I drilled two extra holes in the inverter's mounting rail to put two extra screws in to affix the Z-bracket securely to the inverter. Nicely tightened with a spanner.

Then I could lift up the inverter so the rail on the top was a little higher than the wall mounted bracket and let it gently slide down into the cleat. Way easier than trying to hold the inverter up while screwing in the mounting screws.



Once it was up I could remove the front lower panel to expose inverter's lower mounting screw holes and use a small masonry drill bit to mark the location of the lower drill holes.

Lift the inverter back up and off the bracket so I can drill those lower mounting holes and insert the plugs. These were smaller plugs, they only need to prevent the inverter from being knocked up and off the top bracket and from being pulled out away from the wall.

Lift the inverter up and onto the bracket again, then screw in the lower mounting points and it's solidly in place.

I note that when removing the inverter's lower panel I need to unplug some fairly fragile looking connectors. So that takes some care. I left those connectors disconnected for now since I'll need to remove that panel again when I do all the cable connections. While there should only be one way to reconnected them, I should have marked them with a sharpie before unplugging to make it clear which side is which when plugging them back in.

Now while this is technically mounted outdoors, it is well protected under a 2 metre wide eave and doesn't get sun. The other inverter is my Fronius 10 kW Symo 3-phase grid-tied unit. Between them is my main circuit board.

I don't have many options for where else to mount it. It's close to the MCB and while it looks a little impeded for airflow on that side, the MCB is shallower than the inverter and there is still pretty good air flow.



That was enough for today. I'm a bit hammered from a big day yesterday.

There are numerous next steps but I think first up I'll have a go at mounting the battery's DC breaker onto the wall beneath the inverter. I have a 250 A ZBeny and enclosure and I'll mount the breaker and enclosure directly beneath the inverter right under where the battery cables connect, roughly where shown in the pic below. They are quite chunky units.



I'm going to need some bigger battery cable and suitable lugs as well.

Once I've done that I'll swap all the existing inverter's cabling over so it can at least be functional.

I will have to reconfigure the small off-grid PV array before connecting that. It is currently in a 2S3P arrangement because the smaller inverter has a low 105 V Voc limit, while this unit has a 500 V Voc limit. The 6 x 375 W panels will be fine for one MPPT for now. Later I can add more solar PV, I have the roof space for it.

I'll probably also relocate the PV disconnect to be right under the inverter. Keep it consistent with the grid tied PV system for shut downs. I may add a second disconnect given the inverter has 2 x MPPT inputs.

I eventually plan to make upgrades to the AC circuit side of the cabling. Multiple elements to that.

In the space under where the MCB is I plan for the electrician to install two more circuit board panels (the MCB is full) and reorganise the whole board. I want a separate essential loads panel. Currently that essential/non-essential circuit split is done by the way the wiring to the transfer switch in the MCB is done. It works, is legal, but it's messy and I want the flexibility to be able to move circuits between essential / non-essential in future.

Never ceases to amaze me how long each little part of the process takes but nice to have one bit done.

 

[wattmatters]

We had a 4-hour long grid outage last night. We were already running from the batteries so all good!

 

[wattmatters]

Been a bit of a delay with the project but managed to get some more done today, this time the battery DC breaker. It was actually a lot harder than it should be as the 70mm cable made it tricky. I couldn't use the breaker box glands with conduit. They needed some modification to fit the cable. Adding shrink wrap made them too fat, even after reaming out the glands. I'll use a little split loom for a bit of extra protection but the cable entries are well sealed into the breaker box.





Next up will be the cables to the battery (that will be a significantly easier job) and the PV input.

I also need to reconfigure the PV array but that should be fairly straightforward as I can do that at the combiner box.
Plus the connection to the Raspberry Pi for Solar Assistant.

This won't be the end of it as the cabling is temporary and will be partially redone once have some main circuit board changes done by the sparky. Then I'll pull the battery out and reconfigure that as well - I have a Victron Lynx Power In to replace the bus bar set up I current have. This will be more suitable for the potential current carrying capacity and give me the flexibility to add more battery capacity later.

Keen to at least power up the new unit and check it's all working.

 

[Hedges]

Hope your breaker isn't running near full load.
Data sheets I've seen assume a box that allows for some cooling.

Is this installation exposed to rain? If so, I assume lid on box is gasketed, and has a liftable cover to protect breaker handle.
Since I see plants through a window/door opening, I guess it is indoors, so venting the plastic box could be beneficial. (not in a way that lets fingers or screwdrivers reach terminals.)

 

[BenCos18]

Is this installation exposed to rain? If so, I assume lid on box is gasketed, and has a liftable cover to protect breaker handle.
Since I see plants through a window/door opening, I guess it is indoors, so venting the plastic box could be beneficial. (not in a way that lets fingers or screwdrivers reach term

from what I remember from earlier in this thread he has it mounted under his eaves bascilly iirc

 

[wattmatters]

Hope your breaker isn't running near full load.

Thanks for the concern. It won't be even close to running at its rated capacity.

General overnight running will be at around 5% or less of the breaker's rated capacity, with occasional periods at ~25% capacity. Anything above that will be brief with any anticipated peaks at under 50% rated capacity.

Certainly that's my recorded experience to date with the existing system. As an example, in the past 3 months my existing 4 kW inverter has only reached it's capacity limit I think on four occasions, at which point it auto switched over to grid supply. That's about 1/3rd of the breaker's capacity rating.

Daytime charging will peak at less than 20% of rated capacity.

The inverter at its max continual rated output would still be under 65% of rated breaker capacity. In any case my AC breakers are 32 A and at 230 V that equates to being under 60% of the breaker's rated capacity.

Its main function for me is to enable easy shut down, or if something goes wildly wrong. Batteries also have their own circuit protection.

Is this installation exposed to rain?

While outside, it is under a 2 metre wide eave. In the six and half years of being here and some very wild storms in that time, rain never reaches these walls.

 

[wattmatters]

Next up will be the cables to the battery (that will be a significantly easier job) and the PV input.

Added the battery cables yesterday - those cables/conduit emerging from the bottom of the DC breaker box.

Another pic, no big change, just to show the battery conduit. I'll put some saddles on those to keep them neat and secure. That was enough. My back was starting to play up and I have physical limitations on what I can do at times.



Today I might temporarily hook up the battery cables to supply power to the inverter so I can at least verify it is operating. I also need to get a data cable for it, nothing fancy just a USB micro to USB-A cable to connect to my Solar Assistant Raspberry Pi.

I'll also relocate the DC isolation switch to be under the PV inputs. The isolator is currently on a wall about 2 metres to the left.

 

[wattmatters]

I assume lid on box is gasketed, and has a liftable cover to protect breaker handle.

I realise I hadn't answer this directly before. Yes the box is gasketed with a lockable lid to access the breaker switch. IP 66 rating. Given the loads I am running I'm not concerned about venting/cooling.

One thing I didn't show was there are rubber-like inserts designed to fit into the slots between the battery terminals to provide some extra insulation protection between each terminal. I should have taken a photo of them - it's a nice little extra layer of protection.

Since I see plants through a window/door opening, I guess it is indoors

And to clarify, the plants (and pool) you see are actually a reflection in the window. Unit is on an outside wall but is very well covered under a wide eave as mentioned earlier. It won't ever see water/rain.

The box and breaker came as a package unit and it was the neatest option I could think of given the location. I haven't as yet put the plugs into the box's screw holes (I want to be absolutely sure I don't need to open it up again before doing that), although those screw holes don't expose anything to the interior of the box at all.

 

[koobs]

I've been running my inverter through the same breaker you have, with 50mm2 cable for almost a year now. Quite often seeing 125amp loads continuously for prolonged periods when cooking/baking etc.
No heating issues at all. Whole thing stays perfectly room temperature.

 

[wattmatters]

I've been running my inverter through the same breaker you have, with 50mm2 cable for almost a year now. Quite often seeing 125amp loads continuously for prolonged periods when cooking/baking etc.
No heating issues at all. Whole thing stays perfectly room temperature.

Good to know. They seem like really solid units.

 

[toms]

Yes, those breakers are virtually standard now for Australian installs. Thanks again for continuing to share your power journey, i have been following from the start on this and other forums and appreciate what you have achieved.

 

[wattmatters]

Yes, those breakers are virtually standard now for Australian installs. Thanks again for continuing to share your power journey, i have been following from the start on this and other forums and appreciate what you have achieved.

Thanks. Much has been learned and I maintain a healthy respect for professionals who do this stuff day in day out. it's turned out to be a fun hobby too.

I felt OK enough (back is giving my some grief) to connect the battery, albeit in a temporary fashion, to test the inverter turns on.

It does, no magic smoke, and the display is operating as it should:



Next up I want to find a suitable data cable for connecting to Solar Assistant. Something with a right angled micro UBB plug would be ideal.

 

[wattmatters]

Next up I want to find a suitable data cable for connecting to Solar Assistant. Something with a right angled micro UBB plug would be ideal.

Grabbed a USB cable from the newsagent today, plugged it in and into the Raspberry Pi and turned on the inverter. Solar Assistant picked up the new inverter pretty much straight away.




And all the Home Assistant information and controls appeared automatically as well. Nice



Fingers crossed this means porting over my existing automations will be pretty straightforward.

 

[wattmatters]

Now have the new inverter operational.
Switched over at 6:17 PM this arvo. No magic smoke and the home is now being powered by the new inverter.

Man there are so many little things needed to make sure all is right and good before turning the system on.



Today was reconfiguring and connecting the PV array to the new inverter via the DC isolator (and disconnecting the PV connection to the old inverter). Array is now 6S (was 2S3P).

Adjusting my Home Assistant automations to monitor and control this new inverter turned out to be pretty easy.

Still some tidy up to do but not much, just securing a few more conduit saddles

Next will be two main projects:
i. get sparky in to upgrade main circuit board, swap over the off-grid distribution panel to use this inverter, and upgrade the AC input and output sockets
ii. reconfigure the battery compartment and upgrade DC bus bar with the Victron Lynx Power-in. That will enable easier upgrades to battery storage when/if I do that, as well as provide a far more robust battery connection set up.

It never ends, does it?

 

[crossy]

Looking good

 

[toms]

It really is never ending.

The good thing is if you ever need to build a system for someone else it is a lot simpler to duplicate what you have already done.

 

[wattmatters]

The good thing is if you ever need to build a system for someone else it is a lot simpler to duplicate what you have already done.

I reckon there are so many little decisions unique to each situation I'd take just as long!

In any case I've no intention of ever doing this for others. Once it becomes a service for others, I'd need to be a licensed electrician and solar installer. I'm about 30 years too late to be starting an apprenticeship!

Happy to give advice when asked, and share what I have done.

I think if I ever do add more off-grid solar PV to supplement the existing off-grid array I'll probably get someone in to install the extra array(s). I'm starting to struggle more with the physical stuff and need to pick my battles carefully.

 

[wattmatters]

An update. I recently got our Q4 2022 bill. It was $45.

This is the bill comparison with the same quarter since 2016:



And the grid imports:



2016 and 2017 were before we had grid-tied solar PV.

Throughout these past seven years our total consumption has been dropping as well via a range of strategies and had settled on a new plateau for 2020 and 2021 but 2022 was the first full quarter of having the benefit of both the off-grid battery as well as the hot water PV diverter.

So of the drop of 14.1 kWh/day of imports from the grid between last year and this year, 4.5 kWh was due to moving hot water to use our solar PV instead of overnight grid power, and 7 kWh/day was due to using the off-grid battery to manage evening/overnight loads. The rest would be due to some consumption savings.

The bill impact is obviously an important one, given than tariffs have risen all through those years, and especially sharply in this past year.

I calculated, based on today's electricity tariffs, what our bill would have been like had we maintained our 2016 consumption level and not had the solar PV and off-grid battery. $1754. Compared with $45, I'll call that a win.

 

[koobs]

It's very satisfying to see what effect good PV and a battery has!
My bill was roughly $750 per quarter before PV, $300 per quarter with just PV and is now about $40 per quarter with PV and 45kwh of lifepo4 storage. (In QLD).

Next step is to get an 8kw inverter and wire it up as pass through so that our electricity stays on in a blackout.

 

[wattmatters]

Next step is to get an 8kw inverter and wire it up as pass through so that our electricity stays on in a blackout.

Which is what I now have. A few circuits are not covered by it - the ducted aircon, oven, large split AC, hot water (which uses a PV diverter), one outdoor GPO I use for the pool pump. So any of those operating at night will draw from the grid, nor are they powered during outages. But it's so nice to have what is effectively a whole of home UPS.

I have mine supplying the home via a transfer switch, so if anything should happen to the off-grid inverter then I can flip transfer switch back to grid power. I didn't want to be left in the dark without another option. And still have the generator, just in case!

In QLD

QLD grid under some strain today. Big peak demand event.