Three quotes but need help please.

[johnb2713]

The best kit for heating water is solar thermal.

Well that has to depend on how youre ranking the results surely?

For example if you want to heat hot water to 85 deg C solar thermal wont hack it.
If you need to heat the water during the night solar thermal wont hack it.
If need to heat the water during cold overcast winters day solar thermal wont hack it.

So how do you qualify it as being the best ?

 

[BorisJ]

Well that has to depend on how youre ranking the results surely?

For example if you want to heat hot water to 85 deg C solar thermal wont hack it.

Probably will mid summer, but that is too hot anyway.

If you need to heat the water during the night solar thermal wont hack it.

True nor will solar PV.

If need to heat the water during cold overcast winters day solar thermal wont hack it.

True nor will solar PV.

So how do you qualify it as being the best ?

More efficient for a given panel area.

 

[Bob Smith]

Probably will mid summer, but that is too hot anyway.

True nor will solar PV.

True nor will solar PV.

More efficient for a given panel area.

Mightbe but as more and more people use PV with batteries. you'll be able to heat the water from the batteries whenever you like. Depending on how big your cylinder is it takes 1 to 3kWh to heat the water which is not that much.

I prefer using the space available for PV than solar panels because the electricity generated can be used as electricity for your home, heat the water, or be sold. With Solar, you can only heat the water.
My view though

 

[chris020]

Many thanks for all your replies, really useful and I will be posing all the question posed to the potential installers. Along with additional research on my part.

At the moment, it feels like Q3 is favourite, some additional information they have provided:

Solar PV panels •G83 grid tied inverter

•Aluminium rail/ roofing hooks/ stainless steel nuts and bolts •Double insulated DC cable size depending on current and volt drop •Double insulated AC cable size depending on current and volt drop •MC4 male/ MC4 female connectors

•DC isolators 32-amp 1000 volt per string •AC isolators 32-amp 500 volt

•Total generation meter 100-amp Ofgem approved •Upgrade or installation of fuse board

•Full series of inspection and testing equipment will be used to make sure everything complied with BS7671 and a copy will be given to you

Follow up information provided

•MCS certificate

•EPC certificate (if required)

•Structural engineers survey and certificate (if required)

•Schematic drawing of your solar PV system •Safe shutdown procedures

•DNO (distribution network operator) acknowledgement letter of connection to the grid (if required)

•AC and DC test certificates • Inverter G83certificate

•Datasheet of the solar panels installed •Final invoice of outstanding balance


They also provided a graph as to the expected ESTIMATED MONTHLY ENERGY across the year. Based on the roof facing, near on, south with limited obstruction. Along with an annual performance guide showing RoI of 7 years.

Thanks again.

 

[binky]

I love the way some companies dress up standard gear like it's something special. So standard grid tied inverter, standard DC cable, standard AC cable, etc etc

 

[chris020]

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

 

[Andy1733]

Bigger battery imo

 

[Andy1733]

I started with 4.8kwh battery then double it to 9.6. cost me £1800 to do so. So if the 2 quotes are only 1k difference it's a no brainer. Go bigger

 

[MHarv]

Solax Master and Slave is 11.6kW and is HV many threads discussions on the pros and cons LV vs HV

I went with Solax HV in the end, Master and Slave 11.6kw with Solax X1 AC 3.6 inverter.... as my solar pv
array is Solax X1 Boost 3.6kW G98 was installed prior by some years.

 

[MHarv]

https://www.sma-sunny.com/en/advant...h-voltage-battery-over-alternative-solutions/

 

[johnb2713]

https://www.sma-sunny.com/en/advant...h-voltage-battery-over-alternative-solutions/

Most of that (read all of of that) is snake oil and completely untrue. The ONLY advantage you get is the ability to use thinner cables on battery interconnect and I believe they charge quite a premium for these HV batteries, complete sales gimmick.

 

[MHarv]

Yes you have stated previously but we all have choice's to make at the end of day, same with cars, auto v manual, diesel v petrol v electric
you can go on.... depends on the OP budget informed choice is better than not know what is available plus price... let him decided m8 lol

 

[johnb2713]

Yes you have stated previously but we all have choice's to make at the end of day, same with cars, auto v manual, diesel v petrol v electric
you can go on.... depends on the OP budget informed choice is better than not know what is available plus price... let him decided m8 lol

I agree, just informing him of my opinion thats all.

 

[Bob Smith]

I think the advantage could be mainly on safety because there will be fewer amps in the system while delivering the same power.

As for the sma-sunny article. well, it does not say anything about HV really or how it compares with LV. It mainly focus on DC coupled vs AC coupled batteries.
They could have saved a few words by not adding High Voltage and it would have changed nothing to the meaning of the article

 

[johnb2713]

I think the advantage could be mainly on safety because there will be fewer amps in the system while delivering the same power.

As for the sma-sunny article. well, it does not say anything about HV really or how it compares with LV. It mainly focus on DC coupled vs AC coupled batteries.
They could have saved a few words by not adding High Voltage and it would have changed nothing to the meaning of the article

I’d much rather grab hold of 50vdc as opposed to 100vdc and above is potentially very dangerous.

 

[Bob Smith]

They must be somehow advantages
1) This is new so they would not develop something new if it did not bring any value.
2) car manufacturer are pushing for higher voltage


If I compare with the growatt batteries (I know they have different families but I take the principle is the same) for instance,


1 Battery (2.56kWh) : 25Ax 51.2V = 1.28kW
2 Batteries (5.12kWh): 50A x 51.2V = 2.56kW
3 Batteries (7.68kWh) : 75A x 51.2V = 3.84kW
4 Batteries (10.24kWh): 100A x 51.2V = 5.12kW
7 Batteries (17.92kWh): 100A X 51.2V = 5.12kW
9 Batteries (23kWh) : 100A X 51.2V = 5.12kW

With the HV from Solax

1 Battery (5.8kWh) : 35A X 115.2V = 4kW (datasheet says 3.5kW)
2 Batteries (11.5kWh) : 35A X 230.4V = 8kW (datasheet says 7kW)
3 Batteries (17.3kWh) : 35A x 345.6V = 12.1kW (datasheet says 10.5kW)
4 Batteries (23kWh) : 35A x 460.8V = 16.1kW (datasheet says 14kW)


From the above figures taken from the below datasheets, it is clear to me that the HV batteries will allow a quicker charging/discharging time.

As I explained in a previous thread, I am expecting my panels to generate a peak power of about 8 to 9kW (therefore I will often be above 4kW), if I were to go for the growatt batteries, then they will be the bottleneck and I'll be either wasting energy or sending it to the grid instead of charging the batteries simply because the batteries could not take the charge.

I hope I am not getting my wires crossed with all this. It is Monday morning after all lol.

 

[Andy1733]

Your money m8. You asked for advice. It was given though the final decision is yours. Tbh there's no wrong setup with solar when the sun is shining. You will always produce way more than you need or can store. Imo It's about getting the best setup over the 8-9 months per year that it's viable.
In winter I just charge the batterys using octopus go between 1230am and 430am. If we do get the odd sunny day it's a bonus..

Btw last summer my 4kw setup was producing enough leccy to fill about 25kw of batterys.

 

[chris020]

I did open a can of worms with my question 'GivEnergy 9.5kw battery or the Solex 5.8kw with slave'. All very useful and much appreciated. Just waiting on one more bit of information from supplier before, deposit paid.

Thanks again for all the valuable information.

 

[johnb2713]

They must be somehow advantages
1) This is new so they would not develop something new if it did not bring any value.
2) car manufacturer are pushing for higher voltage

If I compare with the growatt batteries (I know they have different families but I take the principle is the same) for instance,

1 Battery (2.56kWh) : 25Ax 51.2V = 1.28kW
2 Batteries (5.12kWh): 50A x 51.2V = 2.56kW
3 Batteries (7.68kWh) : 75A x 51.2V = 3.84kW
4 Batteries (10.24kWh): 100A x 51.2V = 5.12kW
7 Batteries (17.92kWh): 100A X 51.2V = 5.12kW
9 Batteries (23kWh) : 100A X 51.2V = 5.12kW

With the HV from Solax

1 Battery (5.8kWh) : 35A X 115.2V = 4kW (datasheet says 3.5kW)
2 Batteries (11.5kWh) : 35A X 230.4V = 8kW (datasheet says 7kW)
3 Batteries (17.3kWh) : 35A x 345.6V = 12.1kW (datasheet says 10.5kW)
4 Batteries (23kWh) : 35A x 460.8V = 16.1kW (datasheet says 14kW)

I'm not quite sure what point you're making here BUT a high voltage battery is a greater number of cells in series which increases the voltage and decreases current for any given power level of charge / discharge/ There is no difference other than more in series, thats why I'm challenging the alleged benefits for the additional purchase price. It wont charge any quicker, you still have to charge at less than 1C and towards the end of the charge cycle the process slows down.

From the above figures taken from the below datasheets, it is clear to me that the HV batteries will allow a quicker charging/discharging time.

Sorry I'm being thick here, where does it show HV will charge faster?

 

[Bob Smith]

I agree the C factor is to be taken into account but you do not see it often being advertised.
I also agree that the charge or discharge is not linear.

For the data I mentioned above if I take the growatt the 9 batteries have a capacity of 23kWh and the Solax 4 batteries 23kWh.
So same "size" in terms of energy storage. Now the Growatt will charge at a power of 5.12kW, therefore it will take a good 4hrs.
The Solax's datasheet says for a capacity of 23kWh (4 batteries) says max power 14kW and standard 11.6kW.

So you can store the energy twice as fast with the Solax than with Growatt. As long as you can provide that power.

I understand that the power is Voltage x Amps so for the same power, if you have a lower voltage then you need a higher amperage. However, you cannot increase the amp as you can increase the voltage. So maybe the LV batteries have this limitation.
You can see in the datasheets above that the more batteries to add the more voltage you get from the HV batteries but for some reason, Growatt has limited the increase of amps to 100A.



Consequently, if I were to be limited through the grid or my PV panels to a max power of 5kW, then I wasting the battery's capabilities if I were to go with the Solax. (THe batteries could handle 14kW, but I could only delivery up to 5kW). Fortunately, this is not the case, my PV will provide (this is a conservative estimation so could be a bit more) max 8 to 9kW. Therefore having a battery capable of only 5kW, would be that I will be sending to the grid the extra power the battery could not handle.

Anyway, I think the last few posts should have been posted on the thread about LV vs HV batteries. Here, we were supposed to discuss the 3 quotes to help @chris020