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simon-jukes avatar image
simon-jukes asked

Multiplus 2 48/5000 with Pylontech US5000

Hi all

Just looking at getting my ESS project underway and obviously want to get started asap. Just a quick question. The recommended battery for the 48/5000 is 200 to 800 amp. I believe the US5000 is only 100amp but it does meet the requirement for surge current when starting up. Therefore, is it ok to or did anyone else start with just 1 * US5000 on this inverter and build the system up by adding another battery approx. 3 months later. Solar generation is going to reduce in the UK shortly so the single 4.8kw battery would be enough for take the excess solar until the spring

Thanks

Simon

Multiplus-IIPylontech
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Juha Tuomala avatar image Juha Tuomala commented ·
You probably mean recommended charging current is 200 - 800 ampers.
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simon-jukes avatar image simon-jukes Juha Tuomala commented ·
Hi Juha

I got the 200-800 from the manual next to recommended battery capacity

Thanks
Simon

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Juha Tuomala avatar image Juha Tuomala simon-jukes commented ·
Capacity is measured as current * time, the result is ampere houts, Ah.
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Alexandra avatar image Alexandra ♦ simon-jukes commented ·

It is the rated capacity for lead acid systems.

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simon-jukes avatar image simon-jukes Alexandra ♦ commented ·

ok thanks

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Alexandra avatar image
Alexandra answered ·

@Simon Jukes

You will need 2x 5000 Pylontec to match the nominal current of the inverter.

The Pylon US5000 is a bit short of that. You will see an alarm anyway. So if you want the lifespan advertised get 2. (And less issues).

5000 ÷ 48 = 104A

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simon-jukes avatar image simon-jukes commented ·
Thank you, I will hold off until I have the 2 batteries then


Cheers

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Alexandra avatar image Alexandra ♦ simon-jukes commented ·
@Simon Jukes

If you want to size using peak ratings, you would also need to use the peak of the inverter, in the case of the 5000 it is 9000 so 187.5A, would also need 2 batteries.

So if you see a better deal on other battery makes, check both nominal and peak ratings.

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Juha Tuomala avatar image Juha Tuomala commented ·
That only applies if you run your inverter with its nominal maximum rate which probably is not happening in the most sites. Those are nominal values and useful if you want to design the system based on those. Real use is less and can be good place to save money to get started.
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Alexandra avatar image Alexandra ♦ Juha Tuomala commented ·

@Juha Tuomala

The batteries need to supply the full inverter cuurent in case of fault conditons. Then the inverter can shut down. You do not size a battery for loads only.

It must first be able to supply the inverter fully, then if more is needed to cover energy needs for storage that is added. If not then your system is safe.

Otherwise you are asking for a fire.

Simon-jukes has the correct approach. Wait, buy another battery and then install and use the system.

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Juha Tuomala avatar image Juha Tuomala Alexandra ♦ commented ·
If inverter shuts down, it switches to the grid. Your fires start when you use too small cables or too big fuses.
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simon-jukes avatar image simon-jukes Juha Tuomala commented ·
For info, I am planning to only 2 batteries on each pair of Pylontech cables. 2 pairs of cables once 4 batteries in place. Each pair of batteries, fused by 160 amp NH00 fuses in a 2pole DC fused disconnect. 70mm cables from the Power in to the inverter (0.5m max length)
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simon-jukes avatar image simon-jukes Juha Tuomala commented ·

I am happy to reduce the maximum rate if it means I can get started sooner, giving so much solar away at the moment and they buying back from the gird at night

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Juha Tuomala avatar image Juha Tuomala simon-jukes commented ·

That's what I did. Having the inverter online already has helped me to cut down my consumption and eletric bill by half when it helps to understand the consumption. And I haven't put all my loads behind the inverter yet. With these rates one can speed up aquiring more battery that way.

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Alexandra avatar image Alexandra ♦ Juha Tuomala commented ·

I dont think you fully understand. If a fault developes in the system (electrical or anywhere else it is not safe). The inverter will not be able to shut down and will literally power a fire.


You can use the energy meter from the grid provider to work out energy consumption. So that part is not difficult.

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Alexandra avatar image Alexandra ♦ Alexandra ♦ commented ·
Not to mention when you do add a second battery the first ones state of health will compromise the second one. They become badly mismatched if cycled.
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Juha Tuomala avatar image Juha Tuomala Alexandra ♦ commented ·

You're saying, if a Victron inverter doesn't get enough current from the batteries, it will start a fire.


Good luck in getting them to confirm your accusation.

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l81ker avatar image l81ker Alexandra ♦ commented ·

I'm thinking the same thing as Simon-Jukes, and I agree with Juha Tuomala (terve Juha) that the system can be sized to begin with using configuration, that is also my plan because the costs of making the whole system in one go are prohibitive. The alternative would be to waste money by purchasing a smaller inverter, and then swapping it out later on. Like Juha, the savings could be realised sooner even with some challenges.


Alexandra raises a really important issue tho, what happens in a fault condition.

Thinking about this carefully, I would say "that is what fuses and breakers are for, sized to protect the system in it's current state".

So why not use a suitably sized DC slow fuse, rated for use in this scenario. Set the inverter limits appropriately to the one US5000 battery, with sensible DOD and SOC settings to help preserve the life of the battery as far as possible., and then when the next battery is added, change that fuse to match the new current state of the system.

Do the same with the AC circuit breaker - put in one which is rated lower, according the settings configured. This is far less expensive to change than the whole inverter, and less expensive than the second US5000.

that way - fault condition - system is prevented from causing a fire. Worst case you kill your inverter. A slow fuse will happily work at the continuous rating of the battery and will handle the instantaneous peaks which could be higher, but will go open circuit under sustained loads. A 70A fuse Littelfuse_BF1_58V_Datasheet-523203.pdf (mouser.co.uk) is where I would start my investigation.

Alexandra - I'd be interested in your further thoughts. Thanks everyone who is contributing to the discussion!



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simon-jukes avatar image simon-jukes Juha Tuomala commented ·

The main load on my inverter is going to be the EV charger, which i can set the maximum charge rate

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Juha Tuomala avatar image Juha Tuomala simon-jukes commented ·

My Quattro II in ESS mode can also limit the inverted power so you can virtually "downsize" your inverter from nominal 5000w rate if you like.

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simon-jukes answered ·

ok thanks

I have decided on the Pylonteck, but, if I do change, I will double check the inverter peak

Thanks for the info


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nickdb avatar image nickdb ♦♦ commented ·

The UP5000 has a recommended continuous discharge of 50A, you will need more than 2 for a 5kVA inverter.

screenshot-2022-08-04-at-115047.png

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simon-jukes avatar image simon-jukes nickdb ♦♦ commented ·
Cheers for the info

I am holding off until I have the initial 2 batteries, aiming for 4 eventually

Thanks again

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Juha Tuomala avatar image Juha Tuomala simon-jukes commented ·
Do your calculation what you consume. Constant 5000 watts is a lot of power for residental use. Maybe some washing dryer consumes that much?
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simon-jukes avatar image simon-jukes Juha Tuomala commented ·

Hi Juha

I have an EV, so the excess usage on top of approx. .5 kw is intended towards charging the car. the Zappi charger can be set to only charge if a % of battery / solar is available. If not for this I would have gone for the smaller inverter


Thanks again for your feedback


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l81ker avatar image l81ker nickdb ♦♦ commented ·

The latest spec sheet rates the battery at 80A continuous use (*temperature dependent) so that changes things a little compared with the original launch spec.

Original can be found on Pylon Tech's own website here https://en.pylontech.com.cn/pro_detail.aspx?id=134&cid=23



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simon-jukes avatar image
simon-jukes answered ·

Hi

I've seen the 80amp with 100amp max, this is pushing me towards using a 100 amp NH00 fuse in a fused isolator so it will also be a disconnector when powering down

Simon

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