Setting up solar installation

[pierrecha]

Hello,

I am setting up a solar installation (in France) for the first time. I currently have 38 solar panels (+/-38V, +/-9A), with 35 currently wired in series + parallel (7 panels in series, arranged with parallel wiring 5 times) and am therefore expecting to have 266V (7 panels in a series * 38V) and 45A (5 parallel series * 9A).

I have two solar inverters (Voltacon Hybrid Single-Phase 5Kw Plus Inverters) with just one currently connected to the panels, with 5 12V, 135A batteries connected in series to the inverter.

Output currently stands around 266V (as expected), but instead of having +/-45A, only +/-9A come out of the system (as if only one series was actually connected). The solar panels were checked with a multimeter and they are all functioning correctly.

I am wondering if something is missing from the installation regarding the inverter (perhaps a missing electronic card, relay or converter of some sort) or whether it's in the wiring of the solar panels. Or whether it is something else entirely.

I am hoping to obtain enough wattage to eventually function off-grid.

Thanks in advance for your help,

Pierre

 

[marconi]

The first discrepancy I see is the inverter has a battery voltage requirement of 48 Volts and you have applied 60 Volts from 5 batteries in series instead of 4. The hybrid inverter will be unable to operate correctly at 60V. You may have caused damage to the electronics. Try removing one battery and connecting 48V.

Take great care when handling the Pv panel cables because the voltage is dangerous just like the ac mains can be. Remember to place a fuse or circuit breaker close to the positive terminal of the battery and to cover the battery connections with plastic boots.

You also need a double pole Pv isolator switch between panels and inverter.

 

[pierrecha]

The first discrepancy I see is the inverter has a battery voltage requirement of 48 Volts and you have applied 60 Volts from 5 batteries in series instead of 4. The hybrid inverter will be unable to operate correctly at 60V. You may have caused damage to the electronics. Try removing one battery and connecting 48V.

Take great care when handling the Pv panel cables because the voltage is dangerous just like the ac mains can be. Remember to place a fuse or circuit breaker close to the positive terminal of the battery and to cover the battery connections with plastic boots.

You also need a double pole Pv isolator switch between panels and inverter.

I had previously attempted to connect just 4 batteries to the inverter (making it 48V instead of the 60V here) but it made no difference to the inverter's ability to function - and the range for the inverter is between 48V and 60V, this being a set-up possibility in the inverter's adjoining software.

Thank you still for your reply.

 

[marconi]

Please tell me the exact model of your hybrid inverter(HI) and I will read through the manual and specification for you. Outwardly the Voltacon HIs look similar to the Iconica HIs I have used for off-grid applications.

 

[marconi]

A few thoughts. When you measured the PV current and voltage:

1. Was there any ac load and what power was it?

2. Was the battery already charged/nearly fully charged?

3. Il faisait ensoleille? Est-ce qu'il faisait des nuageux? A midi?

4. Pardonez-moi de demander, est-ce que les panneaux solaires regardent sud? Quel angle d'elevation?

5. If there is a display on the hybrid inverter could you post a picture of what it indicates please?

6. Is the total current equally divided between the five strings? ie: 5A total current and 1A from each string?

 

[pierrecha]

Please tell me the exact model of your hybrid inverter(HI) and I will read through the manual and specification for you. Outwardly the Voltacon HIs look similar to the Iconica HIs I have used for off-grid applications.

I have the manual here for you.

Thank you for your help.

 

[pierrecha]

A few thoughts. When you measured the PV current and voltage:

1. Was there any ac load and what power was it?

2. Was the battery already charged/nearly fully charged?

3. Il faisait ensoleille? Est-ce qu'il faisait des nuageux? A midi?

4. Pardonez-moi de demander, est-ce que les panneaux solaires regardent sud? Quel angle d'elevation?

5. If there is a display on the hybrid inverter could you post a picture of what it indicates please?

6. Is the total current equally divided between the five strings? ie: 5A total current and 1A from each string?

To answer your questions:

1. I measured the PV current and voltage a few times, on one occasion, I had connected an electric heater labeled as 220-240V, and 1500W. It worked then, but when I disconnected it and reconnected another electric heater labeled 220-240V and 2000-2200W, it didn't work anymore.

2. The battery seemed to be charged but now that I've gone through more trials, I'm starting to have doubts. I disconnected one battery now (so that I have 4 batteries connected), as I was told about bulk charge and floating charge (and that when I had 5 batteries connected, it was likely that the bulk charge was largely over the 60V limit indicated on the inverter). Could it be possible that I have the wrong batteries/have batteries that are too small and lacking in power? I've included a photo of the battery if that could help.

3. I tested the installation a few times, but when I tested with the electric heater mentioned above, it was a sunny day with no clouds.

4. The panels face south and have a 30° angle of elevation.

5. I have attached a video of the screen/display of the inverter, where batteries and the 1500W electric heater are connected. (It starts off with no load connected, but you can see in the video the exact moment the heater is connected, as the battery voltage suddenly drops to zero, as if it were emptying them out completely.)

6. I do not know what my current is exactly, as I don't currently have an ampere meter. When I connected my 5 strings of 7 panels each, I had calculated for 9A for each string (and thus 45A total). I have, upon contact with the technical support for the inverter, reconnected the panels with 2 strings of 9 panels/string (which means I expected 9A per string, so a total of 18A for the installation as is, but the video show that the amperes simply aren't there).

I hope that I have provided enough information for you, thank you again for your help.
[automerge]1575294215[/automerge]

A few thoughts. When you measured the PV current and voltage:

1. Was there any ac load and what power was it?

2. Was the battery already charged/nearly fully charged?

3. Il faisait ensoleille? Est-ce qu'il faisait des nuageux? A midi?

4. Pardonez-moi de demander, est-ce que les panneaux solaires regardent sud? Quel angle d'elevation?

5. If there is a display on the hybrid inverter could you post a picture of what it indicates please?

6. Is the total current equally divided between the five strings? ie: 5A total current and 1A from each string?

Here's the video attachment again - I don't think it had worked the first time.

 

[marconi]

The battery you are using only has a capacity of 7Ah (actually 8Ah but I am not amending my sums below for this mistake)- much too small for any off grid living requirement. The 135 figure refers to the cranking current amperage which the battery can provide to a starter motor not capacity. A 12V 7Ah battery can theoretically hold 12 x 7 = 84Watthours or 0.084kiloWatthours of energy and four in series could provide 4 x 0.084 = 0.336kWh. Thus your battery is way too small to store the energy from the PV panels you have erected nor run the inverter for more than a very short while when used to power typical useful ac loads. In fact the quiescent power of the hybrid inverter alone will soon flatten the battery.

By way of example, the off-grid example I have been working on has a 24 V battery made up of two strings of two 12V 200Ah wired in parallel to provide a theoretical capacity of 400Ah at 24V able to store 400 x 24 = 9.6kWh. There are 1.5kW of panels and daily load is about 2.5kWh. In reality the inverter shuts down when the battery voltage drops too low which is when about 5kWh at most has been used. The battery lasts longer if the load is smaller over a longer period and vice versa.

So on a sunny day the PV panel will not take long to charge the batteries and then the solar charger will enter the float phase because the batteries are topped up. In battery mode - no energy being obtained from the panels - your charged battery will power a 1500W heater for 84/1500 hours or 84/1500 times 60 = 3 and a bit minutes but in reality about a minute.

You need to do an analysis of how much energy you require to run your loads over a day/over a week, factor in the variation of insolation by time of year and location, and then size your battery to cope with spells of cloud, nightime and little sun.

I need to finish for now but later on I will say more and provide you with some links to on-line calculators and analysis tools for PV power off grid.

The nominal battery voltage is 48V NOT 60V so the HI requires four 12V batteries in series not five. The charger voltage exceeds 48V in order to charge the battery - as the battery charges the electrochemical voltage rises above 2 Volts per cell/12V per battery and the battery has internal resistance which causes a volt drop. The voltage of the battery in on and off load plus its temperature can provide an indication of the state of charge of the battery.

 

[DPG]

I think Marconi has nailed it with the difference between capacity and cranking amps.

 

[pierrecha]

The battery you are using only has a capacity of 7Ah - much too small for any off grid living requirement. The 135 figure refers to the cranking current amperage which the battery can provide to a starter motor not capacity. A 12V 7Ah battery can theoretically hold 12 x 7 = 84Watthours or 0.084kiloWatthours of energy and four in series could provide 4 x 0.084 = 0.336kWh. Thus your battery is way too small to store the energy from the PV panels you have erected nor run the inverter for more than a very short while when used to power typical useful ac loads. In fact the quiescent power of the hybrid inverter alone will soon flatten the battery.

By way of example, the off-grid example I have been working on has a 24 V battery made up of two strings of two 12V 200Ah wired in parallel to provide a theoretical capacity of 400Ah at 24V able to store 400 x 24 = 9.6kWh. In reality the inverter shuts down when the battery voltage drops too low which is when about 5kWh at most has been used. The battery lasts longer if the load is smaller over a longer period and vice versa.

So on a sunny day the PV panel will not take long to charge the batteries and then the solar charger will enter the float phase because the batteries are topped up. In battery mode - no energy being obtained from the panels - your charged battery will power a 1500W heater for 84/1500 hours or 84/1500 times 60 = 3 and a bit minutes but in reality about a minute.

You need to do an analysis of how much energy you require to run your loads over a day/over a week, factor in the variation of insolation by time of year and location, and then size your battery to cope with spells of cloud, nightime and little sun.

I need to finish for now but later on I will say more and provide you with some links to on-line calculators and analysis tools for PV power off grid.

Thank you (again) very much for all of your help - I will look through once more at my energy requirements (but last I checked, I had expected it to be 8Kw. The important part of this is a 2.2Kw, 14A water pump essential for my olive production.)

Another follow-up question: I have currently only one inverter connected but have another one not currently in use; I'd like to connect it too - will I need twice the number of batteries?

 

[marconi]

JRC Photovoltaic Geographical Information System (PVGIS) - European Commission - https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#SA

Solar Calculator - https://www.bimblesolar.com/solarcalc

You need to know the difference between energy in kWh and power in kW. A 1kW electric heater uses energy at the rate of 1kWh every hour if it was left switch on. In a day, if you ran it for an hour, then for half an hour and later for another hour, the total energy used would be (1 + 0.5 + 1) x 1kW = 2.5 x 1 = 2.5kWh.

If you had a fridge which had a motor of power say 200W (0.2kW) and it was on say 25% of the time during a 24 hour period, then the energy it consumed would be 24 x 0.25 x 0.2 = 1.2kWh.

Power is the rate at which energy is provided/used. So, if your solar panels had a peak power output of 1kW, and delivered this peak output for 4 hours then they would have provided 4kWh of solar energy.

Last (for now) solar panels are like nets catching particles of light called photons. On a very sunny day the solar flux or density of photons per square meter is high. On dimmer days the density is lower. The effective area of panels in the direction of the solar flux sets a limit on the maximum sunshine which can be captured - they do not capture photons which don't hit the panel.

 

[pierrecha]

JRC Photovoltaic Geographical Information System (PVGIS) - European Commission - https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#SA

Solar Calculator - https://www.bimblesolar.com/solarcalc

Thank you - I have estimated the total load to be +/-8Kw at maximum. If I were to have 4 12V batteries at 200A, arranged differently to yours, I'd also get 9.6Kw - this seems appropriate, no?

On the inverter, it says that the maximum battery current is 138A, but it does not give a maximum Ah. How do I know that the 200A (mentioned above) won't be too high? In sum, how do I know what batteries are most appropriate?

When I connect my second inverter, I'm assuming I'll need twice the amount of batteries - how would it be best to connect them?

And once again, thank you for your continuing help!

 

[marconi]

I think you are saying (meant to say) that your maximum energy requirement is 8kWh (the units are very important to conveying the right meaning. You also need to be clear about whether this is 8kWh over 24 hours, over daylight hours only, overnight only.....

These pedantic questions are to help arrive at your actual requirement for panels, batteries and inverters.

If you actually meant that your peak power requirement is 8kW, then one 5kW inverter could not provide this - you would need two. But I would challenge you to confirm whether all the electrical loads which make up the 8kW load are indeed all necessarily on at the same time or could you schedule the loads to reduce the peak power provided by the inverter. AS the power handling of the inverter increases more energy(from the panel or the battery) is wasted as heat and you will soon appreciate the need to use the limited energy carefully if you want to avoid running out.

A 48V inverter delivering 5000W will draw a current of 5000/48 = 104A. It is never a good idea to run electrical equipment at maximum; you always need some power in reserve to cope with the so-called starting surge current of electric motors. I have not yet studied the short term peak power ability of your inverter.

The 200A figure you mentioned is actually 200Amphours - 200Ah which is a way of describing the nominal capacity of a battery. A 200Ah battery could deliver 10A for 20h or 20A for 10h or 1A for 200h. But the chemistry of batteries is such that their capacity is actually reduced the faster it is discharged. So, you would not be able to draw 100A for 2h, more like for an hour at most. Energy is wasted in the battery as heat and this energy is proportional to the current x current. Lead acid batteries can supply high currents up to 100A and for short periods much higher currents. For example the cranking current capacity of the 200Ah battery we use is circa 1200A.

If you had to use two hybrid inverters then yes you would need a battery and set of panels for each. One battery does not have the capacity to run two 5kW inverters - and each inverter-pv pairing needs its own battery to charge.

The four 12V 200Ah batteries would be connected in series.

 

[marconi]

If you look at pages 10, 11 and 51 you will see that there is a limit on the maximum PV current for each PV input - 10A. Your PV panel configuration needs changing because 5 parallel strings of 7 panels is an unacceptable configuration for either of the HI Solar PV inputs 1 or 2- it can produce a current of 5 x 9A = 45A which is in excess of the maximum short circuit current limit for each PV input - 25A. The HI electronics will limit the PV current to no more than 10A which is what you were seeing and queried right at the start of this thread. The allowable configurations of PV panels are as at the bottom of page 11. If you use both PV solar inputs, the number of panels connected to each must be equal as the table describes. You could say have 13 panels in a string on each input. The total open circuit voltage n x panel open circuit voltage must not exceed 900V(!) - minimum is 250V dc.

I need to remind you of the danger of electrocution form touching these high dc voltages (A string of 18 x 36.7V panels produces 660V, 11 panels is 400V)! I strongly recommend you provide extra protection to these cables - run them in conduit and provide high voltage warning signs and limit access to the panels especially by children and animals. A job for a professional electrician methinks so that all the connections are well made off and watertight. You require suitably rated (1000V dc 10A double pole) isolation switches at each array and the inverter - the hybrid inverter has a built in dc switch (item 12 page 6) but this is not an isolation switch.

The battery cabling must be 35mm2 in red(+) and black(-) and again be protected because the latent short circuit current (1200A) is very dangerous. The battery must be shielded so that nothing can be placed on top of it which might short circuit the terminals. A circuit breaker of 150A capacity is required adjacent to the positive terminal which terminates the red cable from the inverter.

Don't forget the inverter requires ventilation otherwise it will overheat.

Ou habitez vous?

 

[pierrecha]

If you look at pages 10, 11 and 51 you will see that there is a limit on the maximum PV current for each PV input - 10A. Your PV panel configuration needs changing because 5 parallel strings of 7 panels is an unacceptable configuration for either of the HI Solar PV inputs 1 or 2- it can produce a current of 5 x 9A = 45A which is in excess of the maximum short circuit current limit for each PV input - 25A. The HI electronics will limit the PV current to no more than 10A which is what you were seeing and queried right at the start of this thread. The allowable configurations of PV panels are as at the bottom of page 11. If you use both PV solar inputs, the number of panels connected to each must be equal as the table describes. You could say have 13 panels in a string on each input. The total open circuit voltage n x panel open circuit voltage must not exceed 900V(!) - minimum is 250V dc.

I need to remind you of the danger of electrocution form touching these high dc voltages (A string of 18 x 36.7V panels produces 660V, 11 panels is 400V)! I strongly recommend you provide extra protection to these cables - run them in conduit and provide high voltage warning signs and limit access to the panels especially by children and animals. A job for a professional electrician methinks so that all the connections are well made off and watertight. You require suitably rated (1000V dc 10A double pole) isolation switches at each array and the inverter - the hybrid inverter has a built in dc switch (item 12 page 6) but this is not an isolation switch.

The battery cabling must be 35mm2 in red(+) and black(-) and again be protected because the latent short circuit current (1200A) is very dangerous. The battery must be shielded so that nothing can be placed on top of it which might short circuit the terminals. A circuit breaker of 150A capacity is required adjacent to the positive terminal which terminates the red cable from the inverter.

Don't forget the inverter requires ventilation otherwise it will overheat.

Ou habitez vous?

The 5 strings of 7 panels were a test run (perhaps overzealous) - I intend to return to my original set-up of 2 strings of 9 panels for one inverter, and 2 strings of 10 panels for the other inverter. (Each would be a little less than the 2*10A outlined in the user manual [would be 2*9.26A for each array]).

The cable running from my inverters to the pv arrays are already underground and thus limit access to the children and animals, and I have isolation switches at both the arrays and by the inverters.

I will buy the appropriate cabling for the batteries - however I have a question regarding the appropriate circuit breaker: does the example in the link below seem appropriate to you? (battery circuit breaker)

The inverter is placed in the garage (where it is much cooler than anywhere else in the house) despite the southern temperatures outside [I am in the South of France].

I have a question regarding the battery set-up: I am intending to have both my inverters put to use with the array set-up described above. Do I arrange 4 12V 200Ah batteries for each inverter, or do I arrange a total of 8 of those batteries with 2 strings of 4, connected to one inverter, which itself is connected by a second pair of battery cables to the other inverter (and having the inverters connected in "parallel" i.e. connected with the communication cables and set up in the SolarPower application in the "parallel" configuration)?

Hope that what I'm trying to communicate is clear to you - and again, thank-you for your help!

 

[pierrecha]

The 5 strings of 7 panels were a test run (perhaps overzealous) - I intend to return to my original set-up of 2 strings of 9 panels for one inverter, and 2 strings of 10 panels for the other inverter. (Each would be a little less than the 2*10A outlined in the user manual [would be 2*9.26A for each array]).

The cable running from my inverters to the pv arrays are already underground and thus limit access to the children and animals, and I have isolation switches at both the arrays and by the inverters.

I will buy the appropriate cabling for the batteries - however I have a question regarding the appropriate circuit breaker: does the example in the link below seem appropriate to you? (battery circuit breaker)

The inverter is placed in the garage (where it is much cooler than anywhere else in the house) despite the southern temperatures outside [I am in the South of France].

I have a question regarding the battery set-up: I am intending to have both my inverters put to use with the array set-up described above. Do I arrange 4 12V 200Ah batteries for each inverter, or do I arrange a total of 8 of those batteries with 2 strings of 4, connected to one inverter, which itself is connected by a second pair of battery cables to the other inverter (and having the inverters connected in "parallel" i.e. connected with the communication cables and set up in the SolarPower application in the "parallel" configuration)?

Hope that what I'm trying to communicate is clear to you - and again, thank-you for your help!

Would these batteries work for my set-up? They seem, at first sight, to fit the description.

Thank-you again!

 

[marconi]

The next lesson. It is expensive to store electricity in a battery. Batteries deteriorate in capacity with the number of charge/discharge cycles and depth of discharge. They also deteriorate if not charged appropriately to their present charge state and type of battery. They also age if kept too warm or charged/discharged very quickly. Good long lasting, slow deteriorating, safe batteries are expensive but a better return on investment than cheaper ones for long term high useage roles. I have only used a good make of batteries - Victron Advanced Gel Matrix - because they are used in a business critical application every hour, every day, all year and need no maintenance and are both quality assured and safe. I have done all the level of investment, return on investment, cost-effectiveness, opportunity cost, pay-back period analysis. You will need to consider the percentage of time you will be using your stored solar energy over a day, a week and a year to gauge how often you need to draw on energy stored in the battery and hence its capacity. In this regard the 'load profile' - how much power plotted against time (day, week, year) is helpful.

Generally speaking the best way to use the off-grid set-up is to use the solar energy as it is generated until you don't need it for doing any work and then to store the surplus but only as much stored as you can reasonably need in reserve until the next spell of sunshine.

Or you could just 'splash the cash' and buy some 'big' batteries of any make and type and see how you get on. In my application we did not have the luxury of doing this.
[automerge]1575364086[/automerge]
Four of those batteries would be an option but before you buy them look at other Gel/AGM brands. Look at the specifications for floating charge life and expected number of cycles of discharge/depth of discharge, and expected life for regular % rate of discharge and manufacturer's guaranteed life and maximum charging current. All the information is given in the specification for the Ultracell. Also read the comments by users of them.

Look at Victron:

12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine - https://www.photonicuniverse.com/en/catalog/full/470-200Ah-12V-Gel-deep-cycle-battery-for-motorhomes-caravans-boats-and-off-grid-power-systems.html

Whatever you buy they need to be deep-cycle (50%) AGM or GEL. Don't buy lorry or car batteries - buy marine batteries.

Sorry a bit rushed - have to go out.


[automerge]1575364665[/automerge]
12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine - https://www.photonicuniverse.com/en/catalog/full/359-24kWh-48V-500Ah-AGM-deep-cycle-battery-bank-with-metal-racking-24-x-2V-batteries.html
[automerge]1575364995[/automerge]
The last for this session - think hard about whether you can cope without electricity for a period of time - for how long? This helps inform the sizing of the battery. Could you rely on a stand--by generator instead during this period of PV & battery being unavailable?

 

[pierrecha]

The next lesson. It is expensive to store electricity in a battery. Batteries deteriorate in capacity with the number of charge/discharge cycles and depth of discharge. They also deteriorate if not charged appropriately to their present charge state and type of battery. They also age if kept too warm or charged/discharged very quickly. Good long lasting, slow deteriorating, safe batteries are expensive but a better return on investment than cheaper ones for long term high useage roles. I have only used a good make of batteries - Victron Advanced Gel Matrix - because they are used in a business critical application every hour, every day, all year and need no maintenance and are both quality assured and safe. I have done all the level of investment, return on investment, cost-effectiveness, opportunity cost, pay-back period analysis. You will need to consider the percentage of time you will be using your stored solar energy over a day, a week and a year to gauge how often you need to draw on energy stored in the battery and hence its capacity. In this regard the 'load profile' - how much power plotted against time (day, week, year) is helpful.

Generally speaking the best way to use the off-grid set-up is to use the solar energy as it is generated until you don't need it for doing any work and then to store the surplus but only as much stored as you can reasonably need in reserve until the next spell of sunshine.

Or you could just 'splash the cash' and buy some 'big' batteries of any make and type and see how you get on. In my application we did not have the luxury of doing this.
[automerge]1575364086[/automerge]
Four of those batteries would be an option but before you buy them look at other Gel/AGM brands. Look at the specifications for floating charge life and expected number of cycles of discharge/depth of discharge, and expected life for regular % rate of discharge and manufacturer's guaranteed life and maximum charging current. All the information is given in the specification for the Ultracell. Also read the comments by users of them.

Look at Victron:

12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine - https://www.photonicuniverse.com/en/catalog/full/470-200Ah-12V-Gel-deep-cycle-battery-for-motorhomes-caravans-boats-and-off-grid-power-systems.html

Whatever you buy they need to be deep-cycle (50%) AGM or GEL. Don't buy lorry or car batteries - buy marine batteries.

Sorry a bit rushed - have to go out.


[automerge]1575364665[/automerge]
12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine - https://www.photonicuniverse.com/en/catalog/full/359-24kWh-48V-500Ah-AGM-deep-cycle-battery-bank-with-metal-racking-24-x-2V-batteries.html
[automerge]1575364995[/automerge]
The last for this session - think hard about whether you can cope without electricity for a period of time - for how long? This helps inform the sizing of the battery. Could you rely on a stand--by generator instead during this period of PV & battery being unavailable?

I am trying as much as possible to become off-grid but if there is no PV or battery available, I was thinking about using the grid, too. However I run into the problem of setting-up the grid to start at the right time i.e. when neither the PV or battery are available, and I don't want anything to return to the grid. In sum, I want to know if the inverter has some sort of charge controller integrated within (perhaps using the SolarPower application?) that would switch to the grid if ever I were to need it?
[I had originally planned for the solar panels to work during the day for my 24H water pump - throughout the summer, for my olive production - and for the grid to start up when the sun is no longer there.]

 

[marconi]

Yes that circuit breaker (150A) is suitable and the one we have used.

You need an insulated spanner of suitable size for the battery bolts:

Insulated Spanners, Sockets and Accessories | Insulated Tools Ltd - https://www.insulatedtools.co.uk/spanners-sockets.html

You need flexible multi-stranded 35mm2 low voltage cable - Here is a French supplier:

Black Hi-Flex 35mm2 cable per meter - EVEA - Kartmasters | Spécialiste du véhicule électrique - https://evea-kartmasters.fr/en/electric-cables/212-black-hi-flex-35mm2-cable-per-meter.html

To make good solid battery connections using 35mm2 cable you will need a special crimping tool:

https://uk.rs-online.com/web/p/crimp-tools/3982270?cm_mmc=UK-PLA-DS3A-_-google-_-CSS_UK_EN_Connectors-_-Connector_Tools_And_Accessories|Crimp_Tools-_-PRODUCT_GROUP&matchtype=&pla-617994355632&gclid=CjwKCAiArJjvBRACEiwA-WiqqwZErgefDvsFTDhOcFp95Kdv5vXMVUqv3c1-UBADJaurPfILbg8ikRoCMbgQAvD_BwE&gclsrc=aw.ds

and a cable lug of the right diameter hole for the battery terminal bolt and entry for the 35mm2 cable:

https://uk.rs-online.com/web/p/crimp-ring-terminals/1225009?cm_mmc=UK-PLA-DS3A-_-google-_-PLA_UK_EN_Connectors-_-Terminals_And_Splices|Crimp_Ring_Terminals-_-PRODUCT_GROUP&matchtype=&pla-394876820878&s_kwcid=AL!7457!3!243856856084!!!g!394876820878!&gclid=CjwKCAiArJjvBRACEiwA-Wiqq0tSLauWi--8vmlLq242sPVfLKBYbRVXS24bANWw4n7htbkT4C0VmxoCS60QAvD_BwE&gclsrc=aw.ds

This is a useful site for some of these items and the terminal boots/covers:

Auto & Marine Electrical Components & Accessories | 12 Volt Planet - https://www.12voltplanet.co.uk/

 

[marconi]

if you look at page 31 of the manual under 'off-grid 1' I have indicated in red the options I think you need to select for the settings in bold black to meet your requirement. It is possible to set up for timed utility charging of the battery using normal rate or perhaps timed off-peak electricity if available. In all cases below the inverter is in the off grid mode which means it is not feeding electricity back into the French electricity network. There is a nice feature whereby if you go over 5kW the utility supply steps in so you might consider only using one hybrid inverter if you only occasionally exceed 5kW or not for long or both: - the item in italics:

PV energy supply priority setting: 1st Load, 2nd Battery
PV power will provide power to the load first and then charge battery. Feed-in to
the grid is not allowed under this mode. At the same time, the grid relay is
connected in Inverter mode. That means the transfer time from inverter mode to
battery mode will be less than 15ms. Besides, it will avoid overload fault because
grid can supply load when connected load is over 5KW.
Battery charging source:
1. PV or Grid: If there is remaining PV power after supporting the loads, it will charge
battery first. Only until PV power is not available, grid will charge battery. (Default)
2. PV only: It is only allow PV power to charge battery.
3. None: It is not allowed to charge battery no matter it’s PV power or grid.
Load supply source:
When PV power is available:
1. 1st PV, 2nd Battery, 3rd Grid (Default)
PV power will provide power to the load first. If it’s not sufficient, battery power will
provide power to the load. When battery power is running out or not available, grid
will back up the load.
2. 1st PV, 2nd Grid, 3rd Battery
PV power will provide power to the load first. If it’s not sufficient, grid will provide
power to the load. If grid is not available at the same time, battery power will back
up.
When PV power is not available:
1. 1st Grid, 2nd Battery
Grid will provide power to the load at first. If grid is not available, battery power will
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provide power backup.
2. 1st Battery, 2nd Grid (Default)
Battery power will provide power to the load at first. If battery power is running out,
grid will back up the load.
NOTE: This option will become ineffective during AC charging time and the priority
will automatically become 1st Grid and 2nd Battery order. Otherwise, it will cause
battery damage.