Batteries 50V vs 100V

[Bob Smith]

I would go for option 3 to keep unnecessary costs down. It would think it's cheaper than the other 2 options as string inverters are quite low cost.

I'll ask on Monday and see if they run away because I already asked too many questions!!!

 

[bladerunnerpv]

@bob you've already got AC coupled system for the main SE roof?

How were you anticipating linking the new output from the smaller roofs and wall and the NW roof to the existing SE-based system? Sorry if I missed this from earlier.

You're planning to fill the NW-facing roof with panels too? How many kWp on NW roof? Is the expense worth it for the generation it will provide?

As to the original question of HV or LV batteries - the only thing pushing me to consider HV for my potential system is the inverter input PV power capability (I thinking around 8.5kWp) and output AC power capability, the SolaX X1 G4 Hybrid 7.5D seems to be a contender as it's quite beefy, but its solely HV compatible, the battery voltage being 80V+.

Is your quote using Solax just because it's available?

 

[Bob Smith]

Hi @bladerunnerpv

Don't worry if you missed something. I am also getting lost!!

My existing system does not have batteries just the FiT scheme which I want to keep for obvious reasons.
Therefore, in order for the new system and old system to both contribute charging the battery I must have AC couple batteries.
I do not know what equipment will be used but after the generation meter of my existing panels (if before then it can invalid my FiT), we have AC current and this will go for Home usage first as it is today, then it will go to the batteries. I supposed there will be some CT clamp.
All installers did not have an issue with having both systems (new and old) charge the batteries

You are correct I am planning to fill my NW facing roof. Last April I considered only the West facing wall but in August I realized I could generate nearly as much on this NW roof than on my SE even with less sun exposure. This is simply because of more powerful and efficient PV panels (I am expecting 5.2kWp instead of 4 and panel efficient ~21% instead of 15%). When I realized this, I thought, what the hell. Let's do a full monty

One of my quotes (managed to get 2!) is Solax for the battery. I have no idea what the reason is. The other quote is Growatt batteries (GBLI6532)



For info

 

[Joules]

As DC arcs do not self-extinguish, they can reach extremely high temperatures. A holistic view should really include a fire risk assessment something not covered that I can see under BS7671 Section 712. However, AC arc detection (AFDD) is covered in an earlier section.

Some inverters have inbuilt dc arc detection that theoretically disconnects the load thereby extinguishing the arc. The same consideration should really be given to HV DC batteries with a DC arc detection and interruption device interposed between the battery and the inverter. The higher the DC voltage the wider the gap that will sustain the arc.

A fire in the roof space can see fire fighters risking their lives by coming into contact with HV DC. I seem to remember a device that attaches to each panel disconnecting it when the fireman switch is operated.

Given the controversial risk of fire from lithium batteries they should really be located outside of the building. Charge capacity in LiFEPO4 and the like degrades substantially at low temperatures.

 

[Bob Smith]

I would go for option 3 to keep unnecessary costs down. It would think it's cheaper than the other 2 options as string inverters are quite low cost.

I have just calculated the Max Voc at minimum Temperature for the 400W Panels.

(The layout so far is as followed:

• 13 panels on the main roof,
• 5 on the wall
• 3 on either side of the small roof)

Following the instructions here and taking -5°C for the expected lowest in Cheshire. It gives 45.23V
As I can fit 13 panels this makes 13*45.23= 588V and the inverter proposed (Growatt SPH6000) has a Max PV Voltage of 550V. So I will have to remove one panel.

This is +1 for the micro inverter.
Alternatively, I could have 12 panels on a string inverter and one micro inverter on the main roof like the rest of the locations.

if I use Tigo optimizer instead. One string will be loaded with 12 panels from the main roof with no tigo optimizer, then the rest (1 from the main roof + 11 panels from the small roof and the wall) with Tigo Optimizer on String 2.


Furthermore, the minimum Voltage per string must be calculated. This is where things start to get interesting.
My worst case scenario is for the panels on the Wall and the small roof + that panel from the main roof). This gives a total of 12 panels but they are facing different directions and there will be partial shading as shown on the pictures above.
Calculating the minimum of panels it gives me 5 panels. This is a problem. This means that there is a risk that too often the 3 panels on the SE small roof will not be enough to wake the inverter up in summer (warmer temperatures). and ever worst. As the sun moves and starts being on the right hand side of the small roof, when the panel on the right starts producing this will not be enough for the inverter. (see sketch below with the shade in the morning)




Tigo Optimizer, if I understand correctly, won't help at all in that situation. I will be wasting sun exposure because not enough panels will be providing enough Voltage.

I am poised to need to go with the micro-inverters option (the most expensive) for the wall and both side of the small roof.

Maybe I missed something and one of you will tell me I am all wrong and there is a better way... Please tell me I am wrong.

Thank you for baring with me and for your patience.

 

[bladerunnerpv]

I've had my eye on those eurener panels

Silly question ... Is mixing landscape and portrait panels ok, is the output orientation dependent?

 

[Bob Smith]

I've had my eye on those eurener panels

Silly question ... Is mixing landscape and portrait panels ok, is the output orientation dependent?

I still do not know if I will go with those Eurener panels (even though they are very efficient and also all black which is nice). First, because they are sold exclusively by one company in the UK and that company has not (yet) provided technical details regarding this challenging area to ensure the panels can produce enough to kick off the MPPT string (see explanation above) even with Tigo Optimizer that they quoted.

Do you know how a panel is built? There are cells put in parallel. To improve performance there are diode bypasses.

In the below illustration, if the shade is perpendicular and covers only 10% of the length of the panel, the panel will not produce any electricity.
If the shade is parallel (along the length) and covers the first 2 rows for instance, then the panel will be able to produce electricity (not at full capacity though)

You'll find many videos explaining this such as this one and part 2 youtube.com/watch?v=ESpsdMFEFZo

I have therefore tried to orient the panel based on maximum coverage and also to take into account this characteristic. I have not found any other argument in favour or against mixing landscape and protrait.

 

[johnb2713]

I still do not know if I will go with those Eurener panels (even though they are very efficient and also all black which is nice).

Hyundai panels are also all black and seem to be available in different efficiencies, the more you pay the better they are.

 

[binky]

I've had my eye on those eurener panels

Silly question ... Is mixing landscape and portrait panels ok, is the output orientation dependent?

Absolutely no difference.

 

[bladerunnerpv]

Thanks Binky

 

[Bob Smith]

High Voltage Battery System should be taken into consideration if looking at Battery Systems for the home, Pylontyech now have
brought out their own HV Battery System which will work with Solax AC inverters, check out ITS website.

Hi MHarv,
would you mind to elaborate a bit more on the advantages between HV and LV if you can.
What I am trying to figure out is if this will make a difference for my house to go with more expensive HV rather than LV.

In term of cycles, batteries life, capacity, DoD they seem to be pretty much in the same ballpark.
I understand HV will charge more quickly.
Do they have a better SoC (state of charge) at 10 years than LV for instance?

I think my house is quite common in term of appliances, washing machine, dryier, dish washer, kettle, owen, toaster, TV, console, computers etc.. I do not have EV but will do with the next 2 to 4 years (are HV better when you have a EV charging point?)
What I do have though is an underfloor heating for my conservatory. I think max power is 3kW. This is a WarmUp.

The question is, while HV seems to be more superior, do I actually need that added benefits?

Thanks in advance for any information you can share with me.

 

[MHarv]

It’s a question of what you need, budget, sizing of battery capacity, battery dimensions, location to fit batteries,
Software integration of battery system
via online monitoring. App based for android mobile/iPhone; access to change parameters via App not including inverter screen.

Solax iPhone App alone can enable/disable settings/parameters to the Solax X1 AC 3.6kWh inverter on the fly, change parameters for DOD, inverter Charge/ Discharge Amp settings, Work Mode Self Use for Summer and Force time Use to integrate TOU settings for Octopus Go time periods which is perfect for me without interaction with having to go to the garage to check settings/parameters on inverter in now cold garage.

My Car EQA and Hypervolt 2.0 can all be done by iPhone Apps for charging full 32 amps or reduce to 6 amps for solar charging 1.4kWh or solar plus Grid/Battery using settings to Preheat car and car battery.

All in all Solar/Battery, iBoost+,EV Charger all working in harmony with Free Solar

There are cheaper alternatives, but this is what I went with for in the end working system via iPhone App

Solax AC-3.6kWh inverter covers 3000 to 3600kWh for the house use any more Load done by Grid, Solar PV up batteries 12% today a bonus.

Do your coatings Pylontech batteries not cheap now, Pylontech do now HV battery system on ITS website but don’t offer the comms, integration, changeable settings that Solax iPhone App has.

Please correct me if I am wrong but I did extensive research into LV and HV for the home owner in residential systems.

Good luck in finding the precise configuration for your design of battery storage.

A lot of Quotes from installers will not tell you all this information, more interested in selling their own wares at a nice profit.

 

[Bob Smith]

A lot of Quotes from installers will not tell you all this information, more interested in selling their own wares at a nice profit.

I could not have phrased it better! That's why I am here making new friends

I already have 4kWp facing South with Fit. I am planning to add panels on both side of a small roof attached to the house facing SE and NW, a wall facing West and the main roof facing NW. This will be a 10.5kW system (if I get the panels I want) with a predicted generation of 7MWh. Add 3.8 from my existing this is about 10.5kWh generation.
The batteries will be AC Couple to allow my existing system to contribute charging the batteries without affecting my FiT.

For the battery size. I am starting at around 10-12kWh capacity (2 batteries less weight) and plan to expand to one or two more depending on my experience the first year. I don't have EV at the moment but will surely get one within the next 2 to 4 years.

Until end of last week all the quotes were with LV batteries, Growatt, Sunsynk for instance.
This is the first time I am suggested a HV, this is also the first time the installer got it right and for the right reason regarding how to connect the panels to the multi orientation and a small number of panels (difficult to get the minimum Voltage on a string to get Inverter kicks off) Wall will have 5 panels at best the small roof 2 or 3 on each side. Because they are the first who not only did not give up on the project straight away but also provided the expected design. I am telling myself they must be right for the HV batteries too. However, I cannot yet validate their hypothesis.

The HV is about 2500GBP more than their equivalent LV. If there are no direct benefits for my set up/use why would I spend that money.
This is what I am trying to figure out. Once I have, as before, I will update the post with my findings.

I hope you now understand better my context.

you wrote:

Please correct me if I am wrong but I did extensive research into LV and HV for the home owner in residential systems.

I still cannot see in your above description what a HV can do that LV can't. Apart maybe going up to 32A. Sorry if I have misunderstood or missed the detail of your extensive research.

Good luck in finding the precise configuration for your design of battery storage.

Thank you. I have learnt to be patient. I have started this project in April... This is a story for another thread (you can t imagine the number of companies who said yes we can install more panels. Ah... on a wall, no not possible..... This is just one example of issues I have had)

 

[MHarv]

What batteries are you comparing? For Price difference between LV and HV

Batteries are really a luxury, like electric seats or panaramic sunroof. Upgrades in cars effect your final price … you could go on like yourself with under floor heating an luxury wait until next April when GPG is extended up to £3000 for another year but also the price kWh is probably be over 0.50p who knows if you can get TOU tariff like Octopus Go, Smart meter required cheap rate with say 10 kW batteries capacity daily savings are visible via App Octopus Watch and other Apps to show half hourly readings energy use age to 3 decimal points and cost price via your Energy Providers Tariff using API into the App software again via the Solax App monitor All Battery vitals; voltage, power, SOC, Temperature of battery, Current in Amps
Don’t think Pylontech or others gives you mobile integration as Solax do.

My EV charger is 32 A which is changeable for solar interpretation with load management, adjustable solar only at 6A. my Solax AC inverter is 16 A
My 2 solax bats (115 volts single battery) combine to 230 volts floating voltage smaller cables 6mm2 lower amps compared to LV batteries

In the end just like cars big engines AMG or diesel all about price but totally different fuel returns now electric is here you won’t believe much you can save on home power per 100 miles.. £2.25 now up from £1.50 for next 9 months yes I miss the engine sound but also save £500 road tax, so yearly fuel and road tax savings gone towards batteries

If Pylontech batteries had the same integration as Solax then would opted for them.

Choice is Yours at end of the day just find CPS Electrician to install. Don’t be sold a system by Battery installer as stated in above threads, get the one you want for the installer to install, plus if you down load relevant materials PDF’s of batteries, inverter’s and UTube video’s you can learn so much and install part as well.

To be honest another battery would be nice having 17.4kWh but the additional expense cannot be justified over Grid use of 2-3 kWh
Per day.. look at this again after March 2023.

 

[johnb2713]

I still cannot see in your above description what a HV can do that LV can't. Apart maybe going up to 32A. Sorry if I have misunderstood or missed the detail of your extensive research.

All of the features mentioned in this thread as advantages of an HV battery are available on my Growatt LV Battery and from what I have seen most modern day battery systems. I can’t find any distinct advantage of a HV battery either, there is only one I can think of and that is smaller cables connecting the battery to the inverter. A potential disadvantage is the greater number of cells in series would increase the risk of failure i.e. 32 cells in series to give 100v ‘v’ 16 cells in series to give 50v. To me, it doesn’t warrant the extra cost at all.

 

[Bob Smith]

I finally opted for the HV battery.

Technically speaking, from what I understand they will charge more quickly, therefore when the sun plays hide and seek with my panels, there are more chances to get more kWh into the batteries.
In addition, by having underfloor heating in one room, the battery will be more capable of copying

and the company has been kind enough to accept my counteroffer.

There will be more details about this project coming soon. I have signed today. Now I hope the surveyor is not gonna want to change the set up I agreed with the rep.

 

[Bob Smith]

What batteries are you comparing? For Price difference between LV and HV

You have the specs of the HV at the top of the thread. For the LV, Pylontech U5000C, Growatt GBLI6532. SAJ B1 5.1 48 for some reason is in between
It will be 2 of them as I want to start with around 10k.

 

[johnb2713]

Technically speaking, from what I understand they will charge more quickly,

Why? how?

 

[Bob Smith]

You are the technical expert I only got it from what I read here and there..... I posted a link above and there are also videos etc.. they all seem to say the same thing.

 

[johnb2713]

You are the technical expert I only got it from what I read here and there..... I posted a link above and there are also videos etc.. they all seem to say the same thing.

I'm no technical expert, I dont take statements unsubstantiated as gospel though. Everything I have seen online such as they charge quicker, they are more efficient and they have a longer life etc not a single one is substantiated in how this is achieved. The individual cells are the same as LV batteries theres just more of them. There seems to be on face value snake oil by the bucket load. I hope they work for you bring all the benefits claimed.