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Dick Murray avatar image
Dick Murray asked

UK off grid home

Hello.

We have the aim of going off grid solar/gen with our UK home, which is entirely electric due to our location. The rear of the house faces South with no shadow, at 52 latitude and we have daily usage figures going back 30 months. I have daylight hours for our latitude, actual usage figures for appliances, ~100sm of roof and an idea of what we want.

Having wired the house all rooms are on seperate split socket/light circuits and all heavy draw items are on seperate circuits. We run split CU and already have a gen which we can switch to when grid power fails for longer than my UPS can handle.

I have a rough idea of the system we want but we want to install it in two stages. Reasons are, monitoring that the system is actually doing what we think it would, switching over the house to a split system, building work which needs to be completed, incorporating an existing Gledhill thermal store and time...

We have a day van which was we fitted with Victron so we have experience.

Aiming for 2x Quattro, 2x MPPT, 15kWh actual battery, plus VE stuff etc...

Has anyone else done a whole house UK off grid? Will Victron or other check over my design? Basically any pointers please!

We want to convert our multi sheet spreadsheet into reality :-)

offgrid
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I am completely off grid in Bala, north Wales.

Just about to install another 2.4 kW of solar onto my existing charge controller.

My panels are mostly LG NeON R 4 360's with another 6 400's going in next week.
There are also 4 slightly older/cheaper units ICO-SMC 160's
(And a few hundred W of odball bits if they are still working)

In full sun with a clear sky I get about rated output when I go out there and adjust the inclination, which is great but an entirely useless bit of info... This is Wales full sun isn't a thing for long most of the time.

As I type, circa 18:00 6/7/22, we have full cloud cover that is bright and thin, its drizzling and my array is doing about 250W on average.

looking at the days figures on VRM I have averaged about 600W between 10 and 4 with the days production so far being 5kWH. this is pretty typical of a day with an overcast sky and in fact my production go's up a little if is overcast but bright, early morning and late evening, I think because I get defuse/reflected light that would otherwise be striking the array at a low angle and of little use.

I would be happy to shar my data with you if it will help you at all.
My records are no grate of what was connected and when, we had an incident during one of the storms early in the year, but you will see from the peek values when the config changed and even then we are only talking a few hundred W of change.

I have two Multiplus 5000's a 48/5000/70-100 linked to a BYD 13.8kWh battery module and
a 24/5000/120-100 hooked up to a 300Ah LiFePo4 bank constructed from Ultramax 12V modules.

My installation isn't a supported configuration...

The Multi48/BYD is a standard build bundled with a solar charge controller and a CCGX in a package that used to be sold as easy solar. (That format has changed/gone now.)

Where I step out of the box is that the generator feeds the 48, the 48's output feeds the 24's input and the 24 feeds the loads. I did it that way for a few reasons, resilience and redundancy being the main drivers.

The 24 is a 24, more expensive than a 48 with the same VA rating, so that I experiment with and add to my battery bank in smaller cheaper increments.
The Ultramax's are cheap, well affordable, relatively speaking but still 750 a pair (Circa 1.4kWh) £/kWh that is on par with the BYD stuff but doesn't require a 7K outlay to add capacity. (Not recommending this battery arrangement, unless you want to play, a guaranteed, integrated solution will make way more sense in just about all other circumstances.)

I manage my system using node red running on a raspberry Pi that also runs home assistant so that I have one point of control that is easy to manage and back up. All of this, bar for the original EasySolar/BYD install is new an under development...And it si going very well so far, although it has raised a few eyebrows.


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Interestingly when I said a couple of years ago that I wanted a an energy management solution that could do things like load shedding and check the weather tomorrow to see if the generator should be run today and that I was planning to take all but critical tasks off the Victron kit it wasn't well received generally...

Now however Victron are offering Node Red integration right in the Cerbo GX and suggesting that integrators use it to augment out of the box services like ESS.

Note you will not be using ESS, no matter how many folk tell you you should, look at the manual section on who should NOT use ESS, right at the top it states Off grid systems.

That means if you want automation or clever beyond the capabilities of the programmable relay assistant, and you probably will, you will need something external to the GX device that hangs your system together to achieve that.

One thing you learn quickly when colouring outside the lines is how stuff actually works and what you can do with it.

Roughly where are you BTW I do industrial integration, hydro mostly, for a living and I am just looking at getting into solar and energy storage.

I am not an expert, yet, and I don't have any relevant accreditations.

I also cant recommend doing what I have done with my system arrangement unless you make a clear decision to go unsupported.

That said I am not entirely sure that this sort of stuff will stay unsupported, there are too many people wanting to do too many different things in none stand situations.
We will see...

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Dick Murray avatar image Dick Murray Alistair Warburton ·

Hello, thanks for the reply!. We've spent a lot of time in Snowdonia NP.

You can find us on https://www.google.com/maps/place/Little+Sodbury+Common

If your BYD is https://www.pluginsolar.co.uk/?product=byd-b-box-pro-13-8kw-lifepo4-lithium-battery-rack then I came across that previously, interested in how it's played with Victron. I short listed them due to https://www.renugen.co.uk/byd-b-plus-lv-battery-module-2-56-kwh-lifepo4/ and https://www.renugen.co.uk/b-box-10-0-byd-10-0-kwh-lithium-iron-phosphate-battery-pack-in-cabinet-4-x-2-5kwh-battery/.

What's your daily kWh usage? We average ~12kWh, which will be lowered as we currently rely on a 11kW on demand heater for showering.

So do you have a GX in the mix controlling everything?

Our house is run on RPi's :-)

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5 Answers
seb71 avatar image
seb71 answered ·

A single South facing PV array is a good option, but for off grid, it would help to split the PV panels into 3 arrays:

  • one facing South (largest array);
  • one facing West (or S-W);
  • one facing East (or S-E).

(For Northern Hemisphere)

Obviously each array with its own MPPT (or more MPPTs for each array if the arrays are very large).

For only 2 arrays, go for a South facing array and a West facing array (unless you have a good reason for a East facing one instead - such as higher energy needs in the morning than in the evening).

It's always better (more efficient) to directly use the energy from the PV panels as much as you can and not from the battery (charged by PV panels).

Also, roof mounting is not the best option if you live in a place where you have snow.

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My array/s are ground mount and the ability to clean them, but more importantly alter the angle seasonally, make a big difference.

They are built from 2X4 and arranged so that there is a bias to being vertical as a result of gravity and force imparted by wind... As in the pivot point is slightly offset.

I can tilt the entire 8 panel array by hand, prop it up and then secure the positioning straps in a new position. I am building a second mount now and will do it the same way.

I am also looking at automating the angle adjustment to see if alterations during the day are going to be worth the cost of doing the drive properly. I will probably start with something simple and temporary.

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Dick Murray avatar image Dick Murray Alistair Warburton ·
You alter for the lower sun in winter, yes? Our two storey house stands ~17' at the ridge so it's short! Some of the roof is only 8' off the floor...
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You had me out on my roof this morning checking when our East face gets sunlight! We were going multi MPPT by way of installing the system in parts, I also want redundancy. West would be tricky but not impossible. Usage is opposite to what you would grid connected, aka run the washing machine on the old night tariff. We rarely get snow and I built the roof so it's on me!
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You had me out on my roof this morning checking when our East face gets sunlight!

Ha ha.

Look for possible shadows in the winter season, when it matters the most. The Sun rises in a very different place in winter (compared to summer) and does not go as high on the sky. So objects which do not cast a shadow now might be an issue in winter.


If you can fit - let's say - at least three 60-cell PV panels (so about 900-1000Wp or more) on a certain side of the roof, I would say it's worth the effort. You can get a smaller (and cheaper) SmartSolar MPPT charger for that smaller PV array(s).

For flexibility get 150/xx models even for small PV arrays.

-------

Regarding adjustable tilt:

For a roof (sloped roof) install I would skip this.

For PV panels installed on the ground, if you have space, just mount a few more PV panels and make the support structure with an angle closer to the ideal winter angle for your location. If the space is limited, then a PV panel mount with an adjustable tilt might be worth the extra expense.

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Alistair Warburton avatar image
Alistair Warburton answered ·

Just a few pics... I thought you might find interesting...

running both up to 60% or so as forecast for the next few days is poor.vrm-overview.png

48-byd-charging.png

24-charging.png

An AC current limit keeps the Genny happy, its only little and on propane.

A charge current limit sets the current drawn by the 24, which as a load for the 48 takes priority over its charging. House loads get the final say here.

The 24 has an ac limit to protect the 48 so we are basically looking at 3 X 4kW devices all capable of simultaneously supplying loads. or working individually to charge/supply or sit idle.

note that the screenshots were not simultaneous and there is a 100W or so discrepancy between ac out on the 48 and ac in on the 24, which I think is inverter losses but I need to look at.

It could be a calibration issue and if it is I don't know right now how to address that.
In the grand scheme of things it isn't all that important.

as-they-are-physically.png


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So you run a deficit and use the gen to top up based on the weather forcast? Hence considering forward running the gen based on the weather forcast?
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lifeingalicia avatar image
lifeingalicia answered ·

I live in nort Spain Galicia - some advantage when going PV...

I found this tool great to simulate and also contro actual.

https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html

I am still grid connected but only draw 20W.... running two houses on a Multi 3000 with so far 10kWh bat and about 5,5kWp PV , soon +1kWp with micro inverters (Spain sorry UK you need a bit more).

We cook / bake on gas and use pellet stoves (2) as on low temp central heating and a wood burner (salon) Hot water is boiler 80L 1kW/2kW and a gas boiler (Holiday house) and we run an air con with excess. So we are not 100% electrical.

I have standard roof install - flat installs and soon facade of about 1kW pure south for winter. I am AC coupled (before and after Multi rule 1.0)

To control limit max usage I have installed some load sheding directly in the distro unit these prevent two washing mashines and/or dryer to run in parallel or run at all when total power demand (other) exceeds 1,5kW.

I use openHab 3.2 on a win10 minipc. openHab can do modbus and has a bridge to use unmodified sonoff´s these switch towell heaters, underfloor warming and the boiler depending on what is avilable.

I have not gone through a full winter with this so I keep the grid.... probaly down scaling connection and so I dont need a gen.

I can wholeheartily say PV / Victron allows me a warm/cool & confortable lifestyle without the usually uncontrollable and ever increasing monthly invoice.....

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Sounds nice, very nice!

The solar tool looks great thanks. I have several customers asking about solar right now.

Have you looked at the Emporia stuff? I am about to hook up a Vue, 16 channel energy monitor. HA can talk to the cloud service and there is a flash available if you want to have the thing entirely local...

Sorry, don't want to hijack the thread no more off topic.

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Alistair Warburton avatar image
Alistair Warburton answered ·

Hi Dick,
No issues at all with the BYD integrated setup...
The default integration will force on DVCC and have the BYD BMS, battery manager, whatever, throttle all input/output. With a 13.8 output isn't a concern, the battery can do way more than the inverter could ever ask.

Charging is another story...
The BYD packs severely limit charge, and to a lesser extent, discharge, below 13C. Our battery is inside but in a cool/cold corner of the house and it quickly became apparent that temperature based current limiting was going to be an issue.
I have added a 40W panel heater and a couple of fans, stuffed in with a bot of foam and cardboard, to heat and circulate air within the BYD box. External insulation go's some way to keeping it warm once it is warm.

I am using a separate temperature controller but there is provision to manage battery temperature using a Victron assistant in the GX.

All in all I, based on personal experience over the last 3 years, would recommend BYD with Victron.
However I have just bought a 24V inverter and hooked it up to Ultramax batteries to see how that go's. Ultimately I want a huge battery bank and I will have to construct that from the ground up, cells and BMS, so the Ultramax are a stepping stone on a learning curve.
It will be interesting to see how the capacity fairs over the next few years.

I will check my original invoice for you and see exactly what I have. It is a B-Box 13.8 but I think there are variants!

My original setup came with a CCGX which coordinates everything on the 48 system.

The new 24 system now has a Cerbo GX installed. I had thought, wrongly, that the CCGX could operate as a gateway for everything but because the GX is designed to create a cogent 'system' from desperate parts there were issues and anomalies.
Buy another GX... Live and learn.

For last 30 days...

Consumption 298kWh
Production 258kWh

So 40kW hrs from the LPG generator... Hence the additional solar and battery capacity.
[That makes my wallet pocket hurt!]

We also don't have the kitchen organised properly yet, everything is electric right now.
[MW combi, two 2.2 induction hobs, contact grill and a toaster... + sundry gadgets.]
I will be adding Gas hobs, to make better use of gas when the sun isn't shining and a full size electric fan oven as we are currently using a large combi microwave which will not be as good, efficiency wise, as a well insulated electric oven.

Water heating is gas, don't ask... Chinese flow through heaters in the kitchen and bathroom.
The washing machine is a single fill, cold by design, compact. We give it hot water when power is limited and let heat electrically if there is plenty of sun.

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Alistair Warburton avatar image
Alistair Warburton answered ·

BTW...
I am currently looking at a full on automation of the Victron kit, with everything else, using Home Assistant as a device gateway and Node Red to do all the automation and provide the dashboard.
I am currently playing with and mulling over weather I use the ESS assistant/nodes/setpoints or just go with single parameters using Modbus, and the odd external component to hang it all together but one way or another I will be retaining full overall control, strategically, whilst letting the Victron kit handle the detail, charging algorithm, limits and the like, internally. Best of both worlds I think.
Batteries protected, energy where I want it, inverter losses minimised.

Happy to confer if you are interested.

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