Solar PV battery options

ELM327 · 13-10-2022 09:53AM

That sounds like the victron quattro I've been looking at. But the same issue arises with 2 different battery types. Both LiFePO4 and 48v but different age or brand. The issue with buying branded dyness batteries (or pylontech or whatever) is that they are 2X or more expensive than buying chinese banks

unkel · 13-10-2022 10:12AM

And even if both are LiFePO4 and 48V, it could be that they are completely different. Some pre made batteries are 15S, some 16S, both are usually called "48V"

Charged the former up to the max level of the latter (or discharge to the min level) and it will be toast very quickly.

Be very aware of what you are buying, don't rush, @ELM327

All those batteries you mention are Chinese BTW. All cells are made in China. Some premade battery packs are made with better other components than others and some are made with better cells. The more expensive ones usually have better marketing and a better brand name. Like Pylontech. Lovely cases, looking really professional. But open one up and you will start crying already.

poker--addict · 13-10-2022 10:35AM

Looking at those lovely cases now unkel😁

looks like 2400 euro for 10kw delivered. That includes Rosen, a brand some installers in Ireland are using I believe. Growatt a better known brand closer to 4000.

most of them seem to claim good for 6,000 cycles.

ELM327 · 13-10-2022 10:58AM

Yes @unkel i know they all come from china. What I was getting at is the difference between fancy premade banks like you say, and non premade stuff.

If I were starting off from scratch I'd buy stuff from china but I've already got a significant (both size and cost) bank of dyness batteries that I'm not willing to change. So I want to add to this in order to expand. The best deals I see on dyness batteries the same as my a48100 are 1.5-2k per 5kWh. Whereas those chinese sellers on aliexpress, you can often buy 8-10kWh or more for that money

SD_DRACULA · 13-10-2022 11:04AM

https://www.boards.ie/discussion/comment/119738557#Comment_119738557

What you could do if you want is order a new set batteries and you will undoubtedly be able to sell your Dyness for 100% cost if not more these days.

the_amazing_raisin · 13-10-2022 12:02PM

https://www.boards.ie/discussion/comment/119738265#Comment_119738265

You'd need 2 Quattros, or 2 Multiplies inverters, each would be connected to a separate DC bus with the different batteries

I'm pretty sure you can't have a big inverter with the batteries all on the same DC bus

Quattros are only needed if you need a built-in generator input, otherwise the Multi is probably what you need

Be aware the Multiplus II and Quattro II are apparently compatible with the Irish grid settings, but I'm not sure if they're approved yet. The bigger Multi II doesn't support parallel inverters, so you're limited to 5kVA per inverter

I think you'd also need another Cerbo controller, or a bigger one like the Octo if you're using managed batteries

ELM327 · 13-10-2022 12:10PM

https://www.boards.ie/discussion/comment/119738839#Comment_119738839

Plenty of food for thought. I'm looking at the quattro for the generator input. While any off grid system should not be predicated on running a genny, it would be naive not to include it as a backup. I already have the generator.

I'm doing a lot of research around blending battery banks. The whole reason I went for dyness batteries is that they were supposed to be modular.

Jonathan · 13-10-2022 12:11PM

Interesting solution over on FB to the 70A Solis DC limit. Use a rectifier to charge the battery in parallel with the inverter. Might be a solution for those with short 2-3 hour cheap periods.

ELM327 · 13-10-2022 12:19PM

https://www.boards.ie/discussion/comment/119738893#Comment_119738893

You'd probably need an inverter not a rectifier. Unless you were charging from another battery or DC source

Something like this (but a 230v version) would work but that's super dodgy IMO

AIMS Power CON120AC36/48DC - Inverter Supply

Here's a UK version actually.

Hugoome Beleeb Series C20 Battery Charger 12V 24V 36V 48V, Pulses of High-Voltage Battery Desulfator Maintainer for Lead-Acid Lithium-ion Batteries: Amazon.co.uk: Automotive

unkel · 13-10-2022 12:41PM

https://www.boards.ie/discussion/comment/119738893#Comment_119738893

Any link to that?

Jonathan · 13-10-2022 01:09PM

https://www.boards.ie/discussion/comment/119739013#Comment_119739013

Its a private FB group so can't link directly, but join and you'll see it as one of the recent posts:

https://www.facebook.com/groups/288045168816481

the_amazing_raisin · 13-10-2022 02:11PM

https://www.boards.ie/discussion/comment/119738886#Comment_119738886

Yeah blending batteries is one of those areas where you've definitely graduated from enthusiasm to industrial scale

I think for Quattros running in parallel you need them connected to the same DC bus

For what you want I think you could have a Quattro with your generator and grid on the two AC outputs and one set of batteries on the DC bus

Then you can have another inverter AC coupled to the output of the Quattro, with the second set of batteries on it's own DC bus

You can split your solar panels across the two DC buses, or keep them on one of you have enough power available in your inverter

There are however a lot of design considerations, the page below might help

https://www.victronenergy.com/live/ac_coupling%3Astart

Also, quick disclaimer, I'm not a solar expert. Get an engineer to design the system properly for you

poker--addict · 13-10-2022 02:21PM

Trying to educate myself on batteries. Looking at 10kw power wall option. $2400 delivered to port. Need to get an idea of extra charges I need to factor.

But first, what does the Max Discharge current dictate? Safety wise is lifePO4 far safer and should I avoid lithium which I understand this Rosen to be?

unkel · 13-10-2022 05:36PM

LiFePo4 is lithium. "Li" is the symbol in the periodic table for lithium. The names of those battery packs in your table start with "LFP" which is a more popular spelling of Lithium iron (iron = Fe in the period table) Phosphate. The exact same thing as LiFePO4 😃

Before you choose your battery, you need to choose your inverter as not all inverters can work with all batteries. Also all those ready made packs are poor value for money. Some of them are poorly made or use poor quality cells. Even the packs with very good reputations. I would strongly advise you to consider making your own pack. It's not hard. Several forum regulars have done it even though they had zero experience with any of this. There are several threads about it here and people are very helpful getting you going and helping you out if you got stuck. It's also a super fun experience and you'll be proud of your achievement.

Ubbquittious · 13-10-2022 05:50PM

https://www.boards.ie/discussion/comment/119739708#Comment_119739708

Is that Chinese stuff? There is a fierce amount of sh1te out there when it comes to normal non grid-tie inverters and also solar charge controllers. You have to be very careful with what you buy

the_amazing_raisin · 13-10-2022 06:41PM

https://www.boards.ie/discussion/comment/119739708#Comment_119739708

Max discharge current is the amount of current you can draw from the battery at one time. Multiply by battery voltage to get the maximum power supplied from the battery

So taking the 100Ah example above, it has a max discharge current of 100A, times 48V gives 4.8kW. So if you try to power a 9kW electric shower off this you won't be able to, the battery will shut down to protect itself

It's also worth noting the recommended discharge current is usually half that amount, and there's often a limit to how long the BMS will allow the max discharge current

You'll need to factor this is when determining your power needs. Ideally you want to be able to draw enough power from your battery to cover any instantaneous demand you're likely to have

One method is to add up the electric loads in your house, but once you do this you'll probably comes up with a 40kWh battery

A more realistic method is to look at what consumers you can manage to reduce the instantaneous demand. For example, not running the washing machine and dishwasher at the same time you're cooking dinner

When your inverter can't cover the demand from solar and battery, it'll draw from the grid. So it's an exercise of matching the battery, inverter and loads

poker--addict · 13-10-2022 07:58PM

Unkel, tempting, but time is precious at the moment with work and fam. That said I spent bloody days picking the quote for panels - but strong argument that I should have been happy to pay a bit more and not lose all that time, hence leaning towards paying a bit more and having a pack I can just hook up - no balancing, no figuring out a BMS, no checking amps or whatever in individual batteries. I’d need to buy all those bits and pieces too for testing.

I don’t doubt it would be cool to do and feel good at the end. But how many man hours (can we say man hours anymore?) realistically will it take assuming an average number of mistakes or issues?

championc · 13-10-2022 09:44PM

Testing is somewhat pointless. It will get you pretty much nowhere. I do feel that you need to charge the cells, let them sit for 24 hrs and charge again if below the max.

Only then will you get the true capacity (whatever that might be)

unkel · 13-10-2022 10:02PM

https://www.boards.ie/discussion/comment/119738893#Comment_119738893

I looked it up, it's basically a cheap Chinese rectifier that needs to be programmed by the manufacturer for a certain DC output voltage but has 3kW power. Saw them on AliExpress for about €66 + €43 shipping, so bloody cheap. R48-3000e3 is the model, can be several different brands

Just bought one. Might come in handy. That said, with our 9 hour period of night rate, most inverters are fine to charge up batteries up to 20kWh from empty to full every night, which only takes about 50-60A

ELM327 · 14-10-2022 08:26AM

https://www.boards.ie/discussion/comment/119740507#Comment_119740507

+1

If I could give myself advice 6 months ago it's that battery packs are the easiest to add on and DIY, build your own bank!

Bif · 14-10-2022 02:05PM

Hi. I’m about to wire in a second Puredrive 5kwh battery onto my (Solis 6kwh inverter) PV system. I was wondering if anybody else has a similiar setup and could send me a photo of how it is wired? Thanks.

Midlakelands · 14-10-2022 02:12PM

Here's my putedrive setip from a from a previous post

https://www.boards.ie/discussion/2058165926/solar-pv-battery-options/p69#Comment_118943927

Jonathan · 14-10-2022 02:45PM

https://www.boards.ie/discussion/comment/119744349#Comment_119744349

While @Midlakelands wiring will work, it doesn't distribute the load evenly across the two batteries. The correct way to wire them is so that the current must flow evenly through both batteries. I'll do up a diagram later.

Bif · 14-10-2022 03:27PM

Thanks for that @Midlakelands!

Bif · 14-10-2022 03:29PM

https://www.boards.ie/discussion/comment/119744515#Comment_119744515

Thanks Jonathan.

Midlakelands · 14-10-2022 03:37PM

https://www.boards.ie/discussion/comment/119744515#Comment_119744515

Yeah I've wondered why they recommend this setup in their documentation. might be worth sending their support a query

con747 · 14-10-2022 05:43PM

https://www.boards.ie/discussion/comment/119744515#Comment_119744515

When I was joining my second battery you had me scratching my head when you told me to do that because the second battery was an end of series and only had 1 + and 1 - connection on it!

Jonathan · 16-10-2022 09:05PM

https://www.boards.ie/discussion/comment/119744723#Comment_119744723

Diagram below. Basically, each battery should have three battery connections. Battery 1 has two + connections and one - connection. Battery 2 has the inverse; one + connection and two - connections.

                     ┌──────────────────────────┐
                     │                          │
                     │                          │
                     │      Solis Hybrid        │
                     │                          │
                     │                          │
                     └────┬───┬─┬───┬─────┬───┬─┘
                          │ + │ │ - │     │CAN│
                          └─┬─┘ └─┬─┘     └─┬─┘
                            │     │         │
                            │     │         │
                            │     │         │
 ┌──────────────────────────┘     └─────────┼────────────────────────────────┐
 │                                          │                                │
 │                                          └──────────┐                     │
 │                                                     │                     │
 │     ┌───────────────────────────────────────────────┼─────────┐           │
 │     │                         Puredrive Battery 1   │         │           │
 │     │                                               │         │           │
 │     │                                             ┌─┴──┐      │           │
 │     │                                             │ UP │      │           │
 │     │                                             └────┘      │           │
 │     │    ┌───┐ ┌───┐       ┌───┐ ┌───┐                        │           │
 └─────┼────┤ + │ │ + │       │ - │ │ - │            ┌────┐      │           │
       │    └───┘ └─┬─┘       └─┬─┘ └───┘            │ DN │      │           │
       │            │           │                    └─┬──┘      │           │
       │            │           │                      │         │           │
       │            │           │                      │         │           │
       └────────────┼───────────┼────────-─────────────┼─────────┘           │
                    │           │                      │                     │
              ┌─────┘           │                      │                     │
              │                 │                      │                     │
       ┌──────┼─────────────────┼───────────-──────────┼─────────┐           │
       │      │                 │ Puredrive Battery 2  │         │           │
       │      │                 │                      │         │           │
       │      │                 │                    ┌─┴──┐      │           │
       │      │                 │                    │ UP │      │           │
       │      │                 │                    └────┘      │           │
       │    ┌─┴─┐ ┌───┐       ┌─┴─┐ ┌───┐                        │           │
       │    │ + │ │ + │       │ - │ │ - │            ┌────┐      │           │
       │    └───┘ └───┘       └───┘ └─┬─┘            │ DN │      │           │
       │                              │              └────┘      │           │
       │                              │            EOL RESISTOR  │           │
       │                              │              IN DN       │           │
       └──────────────────────────────┼──────-───────────────────┘           │
                                      │                                      │
                                      │                                      │
                                      └─────────-────────────────────────────┘

https://www.boards.ie/discussion/comment/119744764#Comment_119744764

Yeah, I'm not sure either. It is a bit odd, but every other battery wiring diagram is wired this way.

https://www.boards.ie/discussion/comment/119745353#Comment_119745353

Yeah, the second PD you bought seems to have been a first generation one with which required a DC combiner box for multiple working.

Bif · 18-10-2022 09:02AM

Thanks for that @Jonathan. Up and running now!

j98c · 18-10-2022 09:44AM

Hi all,

Just received a quote for a 5.6kWp system with 2x2.4kW (4.8kW) batteries.

This is the first quote I've received that has stated more than 1 battery so I'm wondering are there any pros/cons of having a dual battery instead of a single battery?

Solar PV battery options

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