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Victron ESS proposal


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Another lurker planning his system - I have learnt so much from the regulars here!

Residential House / Playschool for 70 kids in Linden, Jhb, 5 to 7 people living here:

Borehole on demand (1kW), feeding the school buildings and half the house, large startup surge (I can see the lights dip)

1 Freezer and two efficient Fridges,

2 X solar tube geysers with 2KW elements, on timers - In summer they use almost zero power. Third solar geyser still needs a timer. Not sure about the element size.

Most of the lights are LED. About 1000w total.  Average probably 300W for six hours per night.

We have replaced all our electric kettles with gas kettles for the hob.

Computers / internet / tv / school sound systems are distributed of different plugs all over, 

Gas hob with electric oven, ...

There are a many other loads that are still heavy - like the clothes iron, clothes dryer, dishwasher, washing machine, vacuum cleaner, carpet cleaner, coffee machine 😳...  Some can be time shifted to solar hours, some are also plugged in to many outlets all over the property.  

The variable part of the current electricity bill is currently only about R26k per year. It is much more in winter than in summer - but we have made a decision to live without electric heaters from this year, so that will help.  We have an efficient wood burning fireplace and a Australian made gas space heater that heats the communal area, and some electric blankets / warm water bottles for cold nights. We also have some portable gas space heaters for special occasions.

 

Proposed system - with questions:

  • Victron Multiplus II (3KVA or 5KVA - I have an 80 Amp single phase supply), in ESS mode.  How much more would the 5KVA cost? I think I have enough load during solar hours load to justify it.
  • Victron add-ons Eg:  Venus GX, VE Direct Usb cable, some kind of current sense pickup for the zero feedback of Multiplus.  I have a bit of an issue here, the main supply cannot get closer than 10m from the Multiplus.  So how do I sense the main supply current? Rerouting the main supply will be expensive.
  • Victron MPPT: Victron Bluesolar 150-100
  • PV Panels: start with about 3.6KW peak, expand to 5.4KW later
    • I like to buy South African - preferably Artsolar 300W in strings of 3 = 900Wp each
    • Mounting hardware for flat mounting on inclined roof.  Half on IBR sheeting, half on Harveytile
    • PV cabling - about 20M to the main four north facing.
    • I plan on having four strings north facing, and one string east and one west, to try to spread the sun hours as long as possible
  • PV frames earth cable / rod - What other earthing should I allow for?
  • PV combine box, with isolators / fuses / surge arrester
  • Battery fuse on positive, isolator?
  • Battery operation: Try to reserve 30% SOC for upcoming loadshedding
  • Battery Options:
    • Revov 2nd life 10 KWh
      • 30% SOC reserved means I can use 7 KWh every day
      • I suspect this will last about 7 years
      • How does it send proper SOC to the Multiplus?
      • Probably a bit cheaper than 2x pylontechs
    • 2X Pylontech US3000
      • 2 X 2.3 KWh = 7 KWh,
      • 20% SOC reserved means I can use 5.6 KWh every day - 80% of the Revov - less electricity saving, and less reserve capacity
      • It should probably last 10-15 years... but I will cycle them deeper due to less capacity so they might last the same...
  • Rewiring main DB - add a second DB for *always on* loads... bypass dual pole changeover switch for servicing. Contains: Lights, computers/internet, fridges and freezer, garage doors - What happens of this draw goes over 2400W?
  • What else do I have to cater for to get it approved by COJ?
  • I am hoping to fit all of this in under R150k - is that reasonable?
  • I am also hoping to save at least 60% of that R26k per year - depends a lot on how much of the load I can move to solar hours, and many other issues
  • Even then I would be roughly looking at a 10 year breakeven period, saving about R15k per year...?  What can I improve?  What am I missing? How can I decrease the breakeven period? I am not even starting to take into account the net present value of the money, increases in electricity rates, decrease in PV panel efficiency / battery capacity because there are too many other variables that will have a much larger influence on the breakeven period.  Eg. the main factor is how much of the electricity bill I can save:  If I can save 90%, the rough breakeven period would be 6.5 years.
  • I just realised I can write of the full capital expense in year 1 - so that will already make a big difference.
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Welcome @Ironman

You have certainly done your homework and it seems like you have thought of everything. 

 

On 2019/08/28 at 6:17 PM, Ironman said:

So how do I sense the main supply current? Rerouting the main supply will be expensive.

You install a Carlo Gavazzi energy meter at the supply and run a coms cable from there to the Venus. Fairly inexpensive. 

On 2019/08/28 at 6:17 PM, Ironman said:

I am hoping to fit all of this in under R150k - is that reasonable?

I think you can get close to that. 

On 2019/08/28 at 6:17 PM, Ironman said:

Revov 2nd life 10 KWh

They will always remain a risk, A risk i am not willing to take. The pylons are doing well and although they are a bit more expensive, they are the safer option. 

 

On 2019/08/28 at 6:17 PM, Ironman said:

(3KVA or 5KVA - I have an 80 Amp single phase supply)

I forgot this question. If i look at your loads, I will opt for the 5kva. 

 

On 2019/08/28 at 6:17 PM, Ironman said:

What happens of this draw goes over 2400W?

The 3 kva can only pass through 32 Amps, this means that after 2400 watt, it will just allow grid to the max of 32 amps to flow through the inverter while adding Pv to the value of its own rating to it. 

The 5 kva unit will pass through 50 Amps while adding PV to the value of its own rating. 

Both these units are to small to pass through your complete setup, so effectively you should try and limit the load to the rating of the unit. 

The older Multi plus had a pass through of 100 amps, I have done installations, where the supply cable to the house is running through the inverter and the inverter will just add what it can at that moment to reduce the electricity bill of the owner. They seldom exceed the capacity of the [panels, but I have seen them drawing loads of up to 10 kwh on a 5kva unit for extended periods  of time without any issue. 

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Linden ... I went to Laerskool Louw Geldenhuys and then Hoerskool Linden. 🙂 

1 hour ago, Ironman said:

... , some kind of current sense pickup for the zero feedback of Multiplus. I have a bit of an issue here, the main supply cannot get closer than 10m from the Multiplus. 

Carlo Gavazzi so no problem as the cable is long enough.

1 hour ago, Ironman said:

Rewiring main DB

Start this first and do the CoCt test to make sure. It may be a cost that becomes unforeseen.

1 hour ago, Ironman said:

What else do I have to cater for to get it approved by COJ?

Good luck with that. Earlier news on that was they don't want you to go grid tied. Check your local regulations and either adhere to them or let them fly, by following CoCT regs and hope that CoJ follows suite.

1 hour ago, Ironman said:

I just realised I can write of the full capital expense in year 1 - so that will already make a big difference.

See SARS is nice. 🙂 

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1 hour ago, Jaco de Jongh said:

You install a Carlo Gavazzi energy meter at the supply and run a coms cable from there to the Venus. Fairly inexpensive. 

 

1 hour ago, The Terrible Triplett said:

Rewiring main DB - Start this first

As you mentioned - I like doing my homework. So... Would it make sense to start with this only:

  • Rewire main DB, add /*Always on*/ DB
  • Install the Carlo Gavazzi energy meter in the main DB, connected to a
  • Venus GX device -> internet...

Questions:

  • Will I be able to get usable time graphs on the VRM portal of the actual consumption that way?  That should also help inform my further buying decisions.
  • The Carlo Gavazzi page only references CCGX - will it work as well with Venus GX?

I see some South African users on the VRM portal demo page - showing actual usage data for today!  Are they aware that the word can see their stuff???🤔

 

As a side note: I have probably been into solar PV longer than some of you - I started running a small off-grid system in Sabiepark (no Eskom allowed) in the early 1990s!

Some history: The system started with

  • 4 x 50W Siemens Panels,
  • A 30A linear voltage regulator
  • 4 x 180AH 12V batteries bought second hand

 

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19 minutes ago, Ironman said:
  • Install the Carlo Gavazzi energy meter in the main DB, connected to a
  • Venus GX device -> internet...

Questions:

  • Will I be able to get usable time graphs on the VRM portal of the actual consumption that way?  That should also help inform my further buying decisions.
  • The Carlo Gavazzi page only references CCGX - will it work as well with Venus GX?

 

It works perfectly with the Venus. 

I have never ran the way you want to , using the Carlo together with the Venus as a energy meter, and theoretically it should work, but wait.... let me phone a friend first.... @plonkster

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43 minutes ago, Ironman said:

Would it make sense to start with this only:

  • Rewire main DB, add /*Always on*/ DB
  • Install the Carlo Gavazzi energy meter in the main DB, connected to a
  • Venus GX device -> internet...

Yes, it would work.

Install the Carlo in the main DB - 1st in line after the main breaker - that all power in and out of main DB goes via it.
Connect the CG to the VenusGX.
VenusGX to the internet.
Create your Venus Portal Account.
And see the data of your DB board coming in ... have never tried the CG on its own but if the VenusGX gets that data, it should sent it.

 

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1 hour ago, Jaco de Jongh said:

have never ran the way you want to , using the Carlo together with the Venus as a energy meter, and theoretically it should work, but

yes, it will work perfectly fine. It's one of the cheapest energy meter combos you can get (compared to a professional logger anyway!), a Pi, a carlo and that cable. Especially if you intend installing more stuff later, then you don't buy the meter twice.

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@Ironman I did a very similar install ! You wont go wrong with the 5kva it seems so cost about R8k more than the 3kva . Do you have a view on your daily and monthly KWH used currently ? 

I would also reccomend looking at solar MD lithium as an option , I have been very happy with their product and technical support. 

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5 hours ago, Mstott said:

Do you have a view on your daily and monthly KWH used currently ? 

I am starting this whole process with just the energy meter / Venus GX / VRM portal just to measure.  I think that a balanced overview of my loads will help a lot in shifting loads to different timeslots and deciding between the MPII 3VKA or 5KVA.

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43 minutes ago, Ironman said:

I think that a balanced overview of my loads will help a lot in shifting loads to different timeslots and deciding between the MPII 3VKA or 5KVA.

Spoken like a wise man.
As much as I would want to have 5 or even 10kva, the numbers in my case simply just do not tie into that picture as most of the loads are <2.5kw and the remaining loads after that are evening loads as the 3kva (2.4kw continuous) with a 3.5kw array shaves a LOT of loads off per day, even in Cape Town winter.

Adding timers to consecutively run bigger loads like geysers, makes the panels work even better.

Grid tied is one hell of a way to save some serious money!

 

On another note. A case sample of the sums we do:
Heat pumps are +- R11 - R15k excl installs and services depending on what size you want. Ideally I need two.
So I came across 2 x 2nd hand heat pumps selling for R6k as I wanted to make the 3kva fit even better.  
Now R6k was excl installation and the "servicing" needed to make them last +-10 years AND assuming the ambient temp is optimal for the heat pumps to work at their best.

Long story short, to save a whopping R123 per month (assuming I use 2kw from Eskom per day to heat 2 geysers) I needed to spent R6k + installation + services ... I will not make that money back in 10 years IF the heat pumps last that long and can shave off 2kw per day every day for 365 days of the year.

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The other thing to think of , is if the grid is down then you have no supplement electrical supply it kind of limits your options. So if the geyser is on at lunch time then don't try the microwave oven etc.  on a 3kva unit, or a better example is in the morning the coffee machine wont work together with the hair dryer.

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1 hour ago, seant said:

The other thing to think of , is if the grid is down then you have no supplement electrical supply it kind of limits your options. So if the geyser is on at lunch time then don't try the microwave oven etc.  on a 3kva unit, or a better example is in the morning the coffee machine wont work together with the hair dryer.

I don't think that is how the MP II works... If I am wrong, will the people with Victron ESS knowledge please jump in and correct me? 

I am going to move my critical load to the /*always on*/ output of the Multiplus II:

  • Lights (LED)
  • Computers/TV/Internet, cellphone chargers
  • Freezers / Freezers
  • Borehole...

These should be less than 2400W total - if not - that is a case for getting the 4000W model.

The point is - I have to make peace with the fact that in a loadshedding  mode, only these items will have power.  I want these items to be able to be carried 24/7, as longs as there is sunshine during the day, so I don't want to overload this circuit.

All other loads: oven, geysers, coffee, hair dryer etc - they will be dead - the Mupliplus II will disconnect itself from the main DB where they are drawing power. Geysers at least have direct solar heating too.

However, while there is power from outside, all the non-critical loads will be supplemented by the MP II from battery AND/OR solar, up to 2400W (or 4000W) - to save money!

And I think that if I know there are multiple loadshedding periods coming up, I can always temporarily increase the reserved SOC from 30% to say 70% to help the batteries to survive the virtual off-grid situation.

 

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Yes that's fine , thought I want to use my coffee machine and the Mrs needs to use the hairdryer so for me the 5kva unit was the answer. Some folks run their geyser off PV power . So , if say eskom is out for a week, then you are going to end up using some not so critical items and if you don't have the reserve on a 3kva unit to do so , then consider getting the 5kva unit . If you want to run the borehole pump which I'm guessing could draw around 2kw maybe more on start up so with a few other thing running you could be close to the upper limits of the 3kva MP II .

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54 minutes ago, Ironman said:

I don't think that is how the MP II works... If I am wrong, will the people with Victron ESS knowledge please jump in and correct me? 

If the MPII is installed grid tied, all the power it can produce from solar, will go into all the DB's in the house with ESS adding batteries to that flavour. THAT is where the savings lie.

As you say, if Eskom goes off, the MPII will only supply the "Always on" DB with power for both batteries and / or solar.

55 minutes ago, Ironman said:
  • Lights (LED)
  • Computers/TV/Internet, cellphone chargers
  • Freezers / Freezers
  • Borehole...

All of the above is not a problem on a 3kva bar the borehole pump. 

That pump makes it more of a 5kva unit, unless you very carefully manage the loads.

If you are unsure, go with 1 x 3kva and if you find it a bore to manage the loads, buy a 2nd unit and parallel them = 6kva / 4.8kw continues power.

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1 hour ago, The Terrible Triplett said:

buy a 2nd unit and parallel them = 6kva / 4.8kw continues power.

...but then the system will never be legal, over 4.6 kw, grid tied, 80amp supply. So I don’t think that is an option. 

I got a quote today for the energy meter / Venus GX, and as soon as sparky is ready to split the db, I will purchase and get that installed to measure.  Then I will have a very good idea of the 3kva / 5kva decision. 

Thanks for all the help.

 

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14 hours ago, Ironman said:

The point is - I have to make peace with the fact that in a loadshedding  mode, only these items will have power.  I want these items to be able to be carried 24/7, as longs as there is sunshine during the day, so I don't want to overload this circuit.

 

13 hours ago, seant said:

I want to use my coffee machine and the Mrs needs to use the hairdryer

I have a 3KVA Multi. No problem with a hairdryer of around 2kw, and no problem with the coffee machine. The older "percolator" machines actually doesn't use that much. We have a bean-to-cup machine now and this sucks a good 1.7kw when brewing, and it is no problem. Even the washing machine runs just fine, it needs around 2.2kw for a few minutes to heat water and that too is no problem. I can even run the Microwave for short periods to heat things, or boil a kettle. The trick is simply not to run them all simultaneously.

What I did to make it unlikely that we'll run things simultaneously is to leave the heavy ones on the grid side on purpose... but I have one power point in the kitchen that has backup power (the fridge is on it). When there is load shedding, I have to use an extension cord from that point to power the appliance I want to power. So it becomes a physical act: The appliance you're using is plugged in and the rest are not.

We get by. It's a little bit of work, but nothing to complain about 🙂

Edited by plonkster
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15 hours ago, Ironman said:

...but then the system will never be legal, over 4.6 kw, grid tied, 80amp supply. So I don’t think that is an option. 

It is not an issue because CoCT says "hardware limit" (like i.e. a 3.5kw array for a 63amp breaker) or "software limit" (limit the inverters max power), which with Victorn one can do. 🙂 

 

13 hours ago, plonkster said:

We get by. It's a little bit of work, but nothing to complain about 🙂

Give that man a Bells. Daai bek soek heuning.

And I also have plugS just for the purpose of no load not possible ... with management off course. 

You can get damn far with a 3kva (2.4kw) inverter.
I even had a large jackhammer running during a building project once - +-1.8kw - whilst powering computers when a power failure happened on a sunny day. No batteries was therefor used.

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1 minute ago, The Terrible Triplett said:

You can get damn far with a 3kva (2.4kw) inverter.

I was amazed at just how capable the 1.6kva was that I had previously!

I was out one evening running the water treatment plant behind the house. This consists of a whole bunch of piping, pumps and filters, which I use to treat well water so we can use it for non-drinking stuff. There is also a pressure pump for the toilets, and all of this is backed up. So I'm standing there and dusk is setting in and the outside lights have turned on, and from the corner of my eye I see the lamp just dipping a bit... the power had failed, load shedding was introduced, and I had two pumps running plus all the other small loads in the house (lights, television, computers)...

With the 3KVA we have only once overloaded it. Wife forgot the AC on in the main bedroom (we have the odd appliance on the wrong side of the divide) and it's a non-inverter unit that needs about 5kw to start, and we already had about 1kw of load on at the time 🙂

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What is the difference between Bluesolar and Smartsolar MPPT?

Can I run multiple MPPTs from one Venus GX?  How will the reporting work? Will it sum the outputs? Can you see each separately?

Can I run mutiple ET112 meters on one Venus GX? One for the main supply and one of the *Always on* circuits? Or does the Multiplus II measure the *Always on* output separately from the inverter output (which will also feed back into the rest of the loads)?

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46 minutes ago, Ironman said:

What is the difference between Bluesolar and Smartsolar MPPT?

Smart solar is more advanced with functions like Bluetooth connectivity. 

46 minutes ago, Ironman said:

Can I run multiple MPPTs from one Venus GX? 

Yes

46 minutes ago, Ironman said:

Will it sum the outputs?

Yes

46 minutes ago, Ironman said:

Can you see each separately?

Yes

46 minutes ago, Ironman said:

Can I run mutiple ET112 meters on one Venus GX?

Yes, but normally used for different applications. One as a Grid meter and a second measuring a PV inverter on the input or output of the Multi. 

46 minutes ago, Ironman said:

Or does the Multiplus II measure the *Always on* output separately from the inverter output (which will also feed back into the rest of the loads)?

It looks at what comes in from the grid, and what comes in from the PV, or battery and then Calculates the Loads on AC out for example. Its  the most accurate measurement/Calculation systems I have work with so far on inverters. 

No need to install a second Carlo, all the info you need will be available. 

The first picture is combined pv values. The ac loads are loads connect before the inverter and the Critical is the loads connected on AC OUT 1

108611600_Example1.JPG.4b3110db24396b7a158d8f2715a2cc38.JPG

The next is showing all the components separately and clicking the right arrow will take you into its history and more in dept data. 

765416546_Example2.JPG.00ddac816a9f48ab85effdc833488d1e.JPG

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21 minutes ago, Jaco de Jongh said:

Smart solar is more advanced with functions like Bluetooth connectivity. 

If you really want to drill down, there's more to it (architecture wise the SmartSolar is a lot more modern), but... functionally speaking, it's pretty much just BlueTooth and SmartNetworking.

With smart networking you can make the solar chargers talk to each other and behave as one. It's not used with an ESS system though. With ESS you let the Venus device control the solar chargers. So for ESS... it's just BlueTooth.

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