Three quotes but need help please.

[johnb2713]

The charge and discharge ability is purely a function of the inverter / charger. It's nothing to do with the battery voltage. It's very misleading of the manufacturers to publish these myths.

So, for example 16S 280A/h set of cells in series would circa 14 kWh, charging at 1/2 C would give a healthy charge current of 140 Ah, the cells would charge in 2 hours.. Now reduce the size of the cells to 140 a/h and put 32 in series to make a high voltage battery, again charging at 1/2 C would give a charge current of 70A and they charged in 2 hours. The ONLY thing that HV does is increase the danger and reduce the current, it does of course add extra complexity - double the number of cells, more connections between cells etc.

 

[Bob Smith]

Well, at the elementary level, physics is what it is. What the manufacturers do is what you just described.
They arrange the cell differently depending on what they want to achieve.

So you can achieve the results charge/speed either way as long as you have the correct number of cells, either way, to get to the desired charge power.

Now clearly, in the 2 examples above with Growatt and Solax, they decided on two different strategies and one gives a faster charge rate.

As for the complexity, what I see is that they provide the same warranty of 10 years >6000 cycles.

Anyhow: They need guinea pigs .

I understand that Gary Does Solar will at some point make a video about LV and HV batteries, let's see what he comes up with

 

[bladerunnerpv]

I am nearly there, decided against the device for the immersion heater.

Hopefully one last question, do I go for the GivEnergy 9.5kw battery or the Solex 5.8kw with slave and what are the for and against.

Thanks again

The Giv 9.5kWh is 100% depth of discharge and unlimited cycles warranty for 10yrs

The Solax 5.8kWh has 5.2 usable (90% DoD) and >6000 cycles warranty

all warranties have some caveats of course

The other thing worth a look at, if you can find the info, is the capacity degradation vs time, e.g. X% kWh retained at Y yrs or the like

enjoy!

 

[Bob Smith]

The Giv 9.5kWh is 100% depth of discharge and unlimited cycles warranty for 10yrs

The Solax 5.8kWh has 5.2 usable (90% DoD) and >6000 cycles warranty

all warranties have some caveats of course

The other thing worth a look at, if you can find the info, is the capacity degradation vs time, e.g. X% kWh retained at Y yrs or the like

enjoy!

100% DoD does not exist. I have learned from Sunsynk who also claims 100% DoD that they actually keep about 10% hidden. In other words if the battery is 10kWh, they say it is 9 with 100% DoD. A bit of a marketing blabla. So if you take 2 Solax you also get around 10kWh of usable storage despite 90% DoD.
With Sunsynk (and I take this is the same with other brands) you can bypass the parameters to use that extra kWh but you invalidate the waranty.


I like you other point.
The degradation over time. I only saw a specs on sunsynk battery that said SoC @ End Of Life 40%.





I talked to Sunsynk directly in the UK and they told me End Of Life meant 10years. In other words they'll guarantee 40% available capacity after 10 years ( based on normal usage blablabla). This is the minimum, it should be more but they won t promise you this.
I never saw any other brands (solax, growatt, Giv, Tesla, Pylontech) that gives this type of information.


Once @johnb2713 shared a diagram of EEV cells and they had about 10% drop of available capacity

 

[bladerunnerpv]

Hi Bob, that's what Giv quote, I suspect they have a reserve like the others though and only publicise the usable capacity, which let's face it seems more honest than selling a battery capacity some of which you can't use. Who would sell 5 metres of carpet and say you can only use 4.5m for example?

If 40% capacity remains at 10yrs, at which point I'd probably feel like I'd consider replacing them, then which warranty would feel more important, unlimited cycles for 10yrs or 6000 cycles? It a choice to make.

 

[chris020]

One final point, so do we need Bird Protection £300 to stop small birds nesting under panels. If not fitted, what are the problems?

 

[Bob Smith]

One final point, so do we need Bird Protection £300 to stop small birds nesting under panels. If not fitted, what are the problems?

I do not have such protection on mine installed in 2016 and I have never had any birds nesting and I have not considered them for my new install.
I personally do not really know what problem they could cause. I could imagine that their droppings could "attack" the cables over time. I see the damage they have done to my car one year!

 

[chris020]

Thanks, Bob that is £300 saved.

 

[Murdoch]

Thanks, Bob that is £300 saved.

DO have the mesh installed.

Your saving will turn into a huge cost when the damage occurs AND just consider how many pigeons will start to use your roof and panels as a roosting place - the noise, the dung and the damage

 

[binky]

Thanks, Bob that is £300 saved.

it's a bit of a catch 22, if the pidgeons decide they like your panels they are a right pita to move on and bits of nesting material sticking into the panel backsheets can cause issues, but of all the installations I've done, none have had pidgeons

 

[Murdoch]

The pigeons live our neighbours panels and a local block of flats with a huge number of panels has more pigeons than I’ve ever seen around here

£300 on a £12k cost is nothing imho

 

[Geoff1946]

I had never heard of bird protection when I bought my system in 2013/14 so I don't have it.
As it's on a bungalow I can see straight up under the panels and I keep an eye out that no-one is considering moving in. If they do action will be swift.
Around here though, seagulls rule the roost and hopefully they are too plump to want such a location.

 

[Bob Smith]

As always it is down to risk management!!

On the side note, I am going to have 5 panels on the wall. At the top I will put some bird spikes. There was a video I watched on Youtube from a guy who installed panels on the wall. Later he realized that the birds like to have a look at his garden while sitting on the edge of his panels. He surely did not mind them watching him in his garden but was annoyed by the droppings sliding along the panels. So he installed those spikes afterward.

 

[bladerunnerpv]

w.r.t. battery life etc in a previous thread (from John IIRC) there was a link to this ...
https://www.solarquotes.com.au/blog/home-battery-testing-results/
there's an update here...
https://www.solarquotes.com.au/blog/battery-testing-final-report/
many battery failures, capacity degradation, etc. etc.

not exactly inspiring...

 

[Oldman22]

Have the bird mesh installed. My system was installed in 2014 and for the first few years all was good with no mesh. Then the pigeons arrived and set up home under the panels along with lots of ignitable nesting material. I had to have the panels meshed then to move the birds on. They went next door who also then needed to have their panels meshed.
There are small bird sized gaps still between mesh and concrete tiles and house sparrows have taken up residence in a couple of places but they are easy to make homeless.

 

[Donnie76]

One final point, so do we need Bird Protection £300 to stop small birds nesting under panels. If not fitted, what are the problems?

We don't have any bird protection on our panels and had no issue, although I have read about pigeons nesting underneath them. Its just personal choice.