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Best batteries for Infinisolar?


Daniemj
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I would like to find out what will be the best batteries to go with the Infinisolar 5KW plus inverter. At this stage I do not have batteries,  and I want to start with a minimum usable battery capacity of about 3-4kwh per day. I want batteries that could be up scaled to minimum 15kwh but maybe even 20+kwh per day in future. I have 28 x 265 W solar panels at the moment, but could always add another 5kw inverter in parallel (and panels) when needed.

I do not want to start with  batteries that would limit me on total capacity if I do expand further. I would prefer lithion ion batteries.

 I am assisting my parents (that live next to me) with electricity and I am also considering an electric car in the future. I do not want to go off the grid, but I do want to produce and store enough solar energy in future to sustain 2 houses and an electric car. At the moment I produce just enough energy in winter for my own consumption and in summer almost enough for both houses. (producing between 850-900kwh in winter months and between 1100-1200kwh in summer months).

 I am running the inverter in Grid-tie but once I have the minimum amount of batteries I can set it up in Grid -tie with back up and connect my generator to the inverter. When I do have enough batteries I want to start using that power at night time and during daytime the solar can charge my batteries and supply the load with Grid to back up any shortages.

Any advice?

 

 

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We have this conversation every few weeks :-)

It depends on what you mean by "best". Do you mean the best that I can buy for the money I have available right now, or do you mean the best in terms of lowest long-term cost, or best value for money?

The best batteries right now (in value for money and long-term costs) are LFP (Lithium Iron Phosphate, also called LiFePO4). They are still expensive, but compared to high end lead acids they are worth it and have many benefits, among them the ability to add more capacity later. If you have around 35k to blow on this, then look at the Pylontech batteries. You should be able to get around 5kwh for that amount. It should last a minimum of 2000 cycles, Pylontech says 6000 cycles at 80% DoD (or 4kwh of the 5kwh in this example).

The best bang for buck lead acids are  Trojan T105RE batteries. Eight of those (they are 6V each) will make a 48V bank, at 225Ah will give you a 10kwh bank which at 50% DoD gives you roughly the same 5kwh storage. It will cost ZAR20k and last 1600 cycles. It needs maintenance, the cells needs to be watered occasionally.

For around 12k - 16k or so you can find 4 x 200Ah AGM batteries. Again, at around 50% DoD you should get roughly the 4kwh you want. They will last around 700-900 cycles.

It is clear that the LFP batteries will last the longest and provide the lowest per-cycle cost, but I don't know if that is the yardstick you use :-)

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Where do you stay and what are your circumstances?

How long is a piece of string?

Real comparisons will only be valid for South Africa as power supplies are not the same everywhere.

I have 4 x 2200w Pylontech lithium batteries on a 4kw Infinisolar plus which is maximum for this inverter.  They are charged from the mains power and are utilised for battey backup only in case of power failures.The maximum solar panel watts is also prescribed for this inverter.

Your 7500w solar panel setup sounds high for your 5kw inverter. So you will need to add inverters and batteries if you want to go to your 20kw input.

This will be very very expensive.

Also read up on the difficulties experienced when inverters are combined for a higher output.

So far I have no complaints and they are a fit and forget battery setup - which is what I intended it to be.

But you need to search and read what everyone has post on the subject.

The most amps I use through the infinisolar is when I run the borehole pump which takes it up to 93% at about 16a. I will definitely not do this on the batteries only as the startup amps for the pump is 35a and I don’t want the batteries exposed to a flash load.

When the power is out I only use the low amp part of the db which supplies lights, computers and tv setup. For high amps (ironing, stove, kettle and charging batteries) I will then start the 7kw petrol generator for short periods of an hour or so. It is way more expensive to run but I do it dor convenience sake and not to stress the inverter.

You need to measure your kwhr requirements (a clampmeter is a must) to determine what you need and where you can cut. Again, a lot to be read on this topic.

The common argument is that mains power is less expensive than drawing power from a set of batteries.

And for the solar power to be used someone must be home.

Edited by Johandup
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15 hours ago, plonkster said:

 

The best batteries right now (in value for money and long-term costs) are LFP (Lithium Iron Phosphate, also called LiFePO4). They are still expensive, but compared to high end lead acids they are worth it and have many benefits, among them the ability to add more capacity later. If you have around 35k to blow on this, then look at the Pylontech batteries. You should be able to get around 5kwh for that amount. It should last a minimum of 2000 cycles, Pylontech says 6000 cycles at 80% DoD (or 4kwh of the 5kwh in this example).

It is clear that the LFP batteries will last the longest and provide the lowest per-cycle cost, but I don't know if that is the yardstick you use :-)

I was considering the Pylontech batteries but have read somewhere on this forum that is seems that the infinisolar read a different voltage from the batteries that the BMS itself has and that it could create some problems.

I also saw that the maximum amount of Pylontech batteries that could be connected together is 5. That will limit me in future if I want to expand on adding another inverter and more panels.

3 hours ago, Johandup said:

Your 7500w solar panel setup sounds high for your 5kw inverter. So you will need to add inverters and batteries if you want to go to your 20kw input.

one string of panels are on the west facing roof. The other on the North facing roof. The inverter limits the pv power output to 5000W, but in winter months or during cloudy days, it help having more panels since it provide 5000W for a longer period during any given day.

I am aware that I will need more inverters  if I want to deliver more solar power, but at this stage I want batteries that are capable of supplying a high current (5000W) if needed in order to charge an electric car, washing machines etc.

I produce more power during the day that I can use daytime and I want a battery storage capable of giving me more flexibility in how and when I use it.

 

3 hours ago, Johandup said:

 

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4 minutes ago, Daniemj said:

I was considering the Pylontech batteries but have read somewhere on this forum that is seems that the infinisolar read a different voltage from the batteries that the BMS itself has and that it could create some problems. 

I also saw that the maximum amount of Pylontech batteries that could be connected together is 5. That will limit me in future if I want to expand on adding another inverter and more panels. 

@SilverNodashi is having an issue at the moment. I don't think it's been figured out yet, but it seems to be isolated events so far.

If you're worried about total capacity, then look at BlueNova. They have smaller module sizes and they recently started to advertise that they have new tech that allows you to parallel a smaller module with a bigger one.

The LFP options in South Africa right now are: Pylontech, Blue Nova, FreedomWon and SolarMD/Mypower24.

The battery I know that allows the most expandability is the Murata batteries. Up to 6 or 7 batteries on a controller (1.2kwh each), up to 16 controllers in parallel. Don't know of anyone selling them locally.

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2 minutes ago, plonkster said:

@SilverNodashi is having an issue at the moment. I don't think it's been figured out yet, but it seems to be isolated events so far.

If you're worried about total capacity, then look at BlueNova. They have smaller module sizes and they recently started to advertise that they have new tech that allows you to parallel a smaller module with a bigger one.

The LFP options in South Africa right now are: Pylontech, Blue Nova, FreedomWon and SolarMD/Mypower24.

The battery I know that allows the most expandability is the Murata batteries. Up to 6 or 7 batteries on a controller (1.2kwh each), up to 16 controllers in parallel. Don't know of anyone selling them locally.

I will look at those options. Thanks a lot for the info!

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3 hours ago, Daniemj said:

I also saw that the maximum amount of Pylontech batteries that could be connected together is 5. That will limit me in future if I want to expand on adding another inverter and more panels.

You are limited to 5 modules per stack but can have multiple stacks connected to a busbar. I think with Pylontech you are limited to 40 modules (96kWh).

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22 minutes ago, Chris Hobson said:

multiple stacks connected to a busbar

You might not know the answer to this, but do you know if it appears (from a BMS integration side) as a single battery, or more than one? That is of course the upside to the Murata system, it appears as one big battery from a software perspective.

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2 hours ago, plonkster said:

You might not know the answer to this, but do you know if it appears (from a BMS integration side) as a single battery, or more than one? That is of course the upside to the Murata system, it appears as one big battery from a software perspective.

I think there is a limitation on the BMS which is greater than the stack limit of 5 (I have seen Victron images of 6 modules stacked). The stack limit I think is determined by the Amphenol battery connections which are limited to 125A.

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1 hour ago, Chris Hobson said:

I have seen Victron images of 6 modules stacked

Well that means it appears as one battery, because a Victron ESS setup cannot yet handle  more than one BMS in the system. Or perhaps that system didn't integrate with the BMS.

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18 hours ago, Chris Hobson said:

 

You are limited to 5 modules per stack but can have multiple stacks connected to a busbar. I think with Pylontech you are limited to 40 modules (96kWh).

 

In that case it seems the pylontech batteries would be the reasonable choice. They are the cheapest of the LFP batteries,  compatible with the infinisolar and if needed, I would be able to add more than 1 stack.

I would also like to how does the pylontech batteries compare to the Blue Nova and FreedonWon batteries in respect of reliability and quality?

 

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6 minutes ago, Daniemj said:

I would also like to how does the pylontech batteries compare to the Blue Nova and FreedonWon batteries in respect of reliability and quality?

Time will tell. As an adopter of new technology one always takes a bit of a risk. Pylontechs have TUV certification (https://www.energy-storage.news/news/pylontech-first-recipient-of-tuv-rhineland-vde-safety-accreditation-for-ger) something not even Tesla has. It is a bit difficult to compare apples with apples as Pylontech's cycle life is quoted to a SOH of 60% whereas the industry standard is to 80%. I have just ordered my 4th module so I think they great but I might be missing something about the other batteries. What was definitely true that one could dip one's toes into the Lithium pool with Pylontech for less money than the competitors. This was definitely a consideration for me as I have expanded my bank as cashflow has allowed.

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28 minutes ago, Daniemj said:

I would also like to how does the pylontech batteries compare to the Blue Nova and FreedonWon batteries in respect of reliability and quality?

First thing to note: Pylontech is 15s (15 cells in series), whereas the others are all 16s. It means it operates at a slightly lower voltage, which is not the worst thing in the world, but it does give the others a slight edge on efficiency (voltage efficiency is the largest component in battery efficiency).

Second thing: They use different cells on the inside.

* BlueNova uses Winston cells (made in China), they have a tiny bit of Yttrium in them too. Yttrium apparently improves performance and lower temperatures. For reference, Victron also uses Winston in their batteries. BlueNova used a 3rd party BMS in earlier batteries, if my information is correct, but now use their own. I have no idea how good it is, but have not heard anything bad about the new ones.

* FreedomWon uses Sinopoly, or so I am told, with a Orion BMS. That's a very good BMS, and it is programmable, can be adapted to work with your equipment.

* Pylontech uses their own cells, as far as I know, and builds their own BMS.

* SolarMD uses CALB cells, although not in all of their batteries, there is one newer model that uses something different. I know you didn't ask about this one... just adding for completeness.

In terms of the BMS in each battery, what is preferred is a BMS that does good voltage control, in other words, one that lowers the total voltage to a safe level if there is a high cell. Few BMSes do this. The Orion BMS in FW does this, as well as the Sony/Murata ones (not available here). The rest pretty much publish a static value. For the Infini, it's not going to matter anyway.

So basically... buy the one that's cheapest.

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