Hi,

So opinions please, would you rather have a 24V Axpert with 2 x 260AH batts, or a 48V with 4 x 120AH batts? this is a 3kva btw

I think cost wise it will come out similar, my main points are:
- 48V DC will be more efficient inverting to 220
- 48V vs 24V - will the solar side be as efficient on a regular voltage system
- obviously adding or replacing batteries means replacing 4 rather than 2 which is something to consider.

Any thoughts?

19 minutes ago, Dex_ said:

would you rather have a 24V Axpert with 2 x 260AH batts, or a 48V with 4 x 120AH batts?

I think that 48 V is far better future proofing. You'll want more power one day.

38 minutes ago, Coulomb said:

I think that 48 V is far better future proofing. You'll want more power one day.

that said though, the units output is limited to 2400W regardless, so in terms of more power one day do you mean a greater load or a longer load? i.e higher wattage per hour or more hours? also this said, i feel this system would already exceed our regular usage. I would hope to leach a good portion of the solar "wastage" to run the pool pump

 

that said though, the 48 unit allows parallel operation, there is a 24v version that allows parallel operation also but stocks are non existant

Edited April 3, 20197 yr by Dex_

1 hour ago, Dex_ said:

38 minutes ago, Dex_ said:

I would hope to leach a good portion of the solar "wastage" to run the pool pump

 

Keep in mind that the 3KVA 24V Axpert PV array is limited to 600 watt not enough vir a normal poolpump . You don't want to cycle the battery's all the time .

10 minutes ago, Chris Louw said:

Keep in mind that the 3KVA 24V Axpert PV array is limited to 600 watt not enough vir a normal poolpump . You don't want to cycle the battery's all the time .

 

yeah unless it is the plus model but yes you are correct, i am planning 4 x 300+ W panels thus will need the plus or the 48V system - that should handle the pool pump on its own on good days i think?

Edited April 3, 20197 yr by Dex_

1 hour ago, Dex_ said:

that said though, the 48 unit allows parallel operation

Exactly. So you could add another inverter. At 24 V, the current starts getting insane.

But since you seem to have a specific single load in mind, future proofing seems unnecessary.

I see JSM still does a 36v inverter so there is a 3rd option. I wonder if that unit is on the CoC list?

1 hour ago, Dex_ said:

that said though, the units output is limited to 2400W regardless

I know this wasn't your point, but just to make people aware.

Doubling the voltage, halves the current for the same power.

However copper losses are determined by the square of the current.

So halving the current, cuts the losses to a quarter.

Putting it another way at 24V you need 4 times more copper.

The copper cabling on the DC side is expensive, so I would always advise 48V over 24V regardless of the power.

3 minutes ago, DeepBass9 said:

I see JSM still does a 36v inverter so there is a 3rd option. I wonder if that unit is on the CoC list?

there is a COC list?

2 minutes ago, phil.g00 said:

I know this wasn't your point, but just to make people aware.

Doubling the voltage, halves the current for the same power.

However copper losses are determined by the square of the current.

So halving the current, cuts the losses to a quarter.

Putting it another way at 24V you need 4 times more copper.

The copper cabling on the DC side is expensive, so I would always advise 48V over 24V regardless of the power.

thanks that is a good point for a pro 48v

Something else to consider is the No Load Power Consumption . The 5KVA is high at 50 watt and can use up to 600 watt per night . The KVA 48V Plus is only 25 watt . Can make a big difference on a small battery bank .

2 minutes ago, Chris Louw said:

Something else to consider is the No Load Power Consumption . The 5KVA is high at 50 watt and can use up to 600 watt per night . The KVA 48V Plus is only 25 watt . Can make a big difference on a small battery bank .

 

thanks i never even thought of that, though note i wasn't considering the 5kva in any event but it is a good point to note.

You can have 4 x (xxx) AH wired for 24v or 48v - exact same thing.

The smaller max panels is a very important point to note on 24v vs 48v.
Then again In favour of a 24v bank, is the day the bank must be replaced. Buying 2 batteries and not 4, IF the load fits the 2 battery bank, makes sense IF the array size is acceptable.

So if you need more batteries then 48v with bigger array potential - wins by far.

Or, like I used to do not anymore, 24v small bank with 2 x MPPT's to get more PV. 😉 

 

18 minutes ago, The Terrible Triplett said:

You can have 4 x (xxx) AH wired for 24v or 48v - exact same thing.

The smaller max panels is a very important point to note on 24v vs 48v.
Then again In favour of a 24v bank, is the day the bank must be replaced. Buying 2 batteries and not 4, IF the load fits the 2 battery bank, makes sense IF the array size is acceptable.

So if you need more batteries then 48v with bigger array potential - wins by far.

Or, like I used to do not anymore, 24v small bank with 2 x MPPT's to get more PV. 😉 

 

to me 2 x 300W panels maxes out the charge controller but would it be sufficient even for 2 x 240AH batteries - this seems like an issue to me?

on a new set of batteries if they are barely cycled and treated well they would hopefully last a long time so the cost difference on batteries in say 8-10 years doesnt seem like a factor that writes off the 48V option? that said would 2 x 335-350W panels be considered enough to handle 4 x 120AH batteries? (though i would want to go 4 x panels to increase yield)

1 minute ago, Dex_ said:

on a new set of batteries if they are barely cycled and treated well they would hopefully last a long time so the cost difference on batteries in say 8-10 years

The could BUT temp plays a huge role with the chemical reaction in the batt. With lead acid, bet on 5 years. If they last longer, bonus!!!

If you have 2 x 240ah batts, you need to be able to charge them at between 8% (slow not good idea), 10% is better and with load shedding, up to 15% of the ah rating of the bank.

If the MPPT with the panels can do that whilst powering the load, from the panels, then you are ok.

Can the MPPT charge the bank at 10%-15% of the banks AH and power the load?
600w of panels for 5.5 hours peak sunlight per day may be insufficient I would guess.

9 minutes ago, The Terrible Triplett said:

The could BUT temp plays a huge role with the chemical reaction in the batt. With lead acid, bet on 5 years. If they last longer, bonus!!!

If you have 2 x 240ah batts, you need to be able to charge them at between 8% (slow not good idea), 10% is better and with load shedding, up to 15% of the ah rating of the bank.

If the MPPT with the panels can do that whilst powering the load, from the panels, then you are ok.

Can the MPPT charge the bank at 10%-15% of the banks AH and power the load?
600w of panels for 5.5 hours peak sunlight per day may be insufficient I would guess.

i am referring to omni solar batteries - agm gel hybrids, they claim a 1 year design life and looking at the cycle chart i should theoretically get 3000 cycles even if i went to say 40% DOD, thats 8 years or so? or am i misunderstanding something?

10% would be 26 Amps if i am not mistaken? - those panels in series i think produce somehing like 18Amps? (see this is where i get a bit lost, to me at peak they deliver 600W's say, which over 5 hours should replenish 3000W - this is how i learnt/understood it - which from what i can tell is wrong?)

23 minutes ago, Dex_ said:

i should theoretically get 3000 cycles

Correct, theoretically, in a lab, controlled conditions. Same, in my mind, goes for the claims of the cycles of the Pylons.
Will believe those stats when they go past 5, then 10 then longer years.

Pylon's is for me like cellphone batts. You use them and use them hard and they work, much better than lead acid.
But they don't last decades. 2/3 maybe 4 years IF you are lucky before you charge daily.
And cell batt tech is tried and tested. 

Trojan are supposed to give 4000 cycles at 20% DOD - but then there are a lot of factors that affect that. So 5 years is good, longer is a bonus.

Download this calculator: https://powerforum.co.za/files/file/28-solar-calculations/
Work out the loads, with the batts, hours per day, temp age of batts, with what panels you would need.

Edited April 3, 20197 yr by Guest

2 minutes ago, The Terrible Triplett said:

Correct, theoretically, in a lab, controlled conditions. Same, in my mind, goes for the claims of the cycles of the Pylons.
Will believe that those stats when they go past 5, then 10 then longer years.

Pylon's is for me like cellphone batts. You use them and use them hard and they work, much better than lead acid.
But they don't last decades. 2/3 maybe 4 years IF you are lucky before you charge daily.
And cell batt tech is tried and tested. 

Trojan are supposed to give 4000 cycles at 20% DOD - but then there are a lot of factors that affect that. So 5 years is good, longer is a bonus.

Download this calculator: https://powerforum.co.za/files/file/28-solar-calculations/
Work out the loads, with the batts, hours per day, temp age of batts, with what panels you would need.

thanks i will check those out right now.

7 minutes ago, Dex_ said:

thanks i will check those out right now.

i will be honest i am not too sure this helps me understand more than what i already do, i might be an idiot though. 

1 minute ago, Dex_ said:

i will be honest i am not too sure this helps me understand more than what i already do, i might be an idiot though. 

Drop me a PM. 

I hear 72V is the new 48V.😉

Also, the very latest of remote powered DC devices use 48V at source (e.g. Battery), up convert to 400V DC transmitted for up to 2000m, and then converted back to 48V DC to power remote equipment. That's the way dense 5G power deployments are being done in Europe. Almost like "Power in the Cloud"

4 minutes ago, Sidewinder said:

I hear 72V is the new 48V.😉

 

Going over 50 V will introduce new challenges. 50 V is concidered a "safe" voltage.

6 hours ago, Dex_ said:

Hi,

So opinions please, would you rather have a 24V Axpert with 2 x 260AH batts, or a 48V with 4 x 120AH batts? this is a 3kva btw

I think cost wise it will come out similar, my main points are:
- 48V DC will be more efficient inverting to 220
- 48V vs 24V - will the solar side be as efficient on a regular voltage system
- obviously adding or replacing batteries means replacing 4 rather than 2 which is something to consider.

Any thoughts?

48 V , but only because it opens up more options for Lithium batteries.

Serioulsy like TTT and Plonkster will preach Victron at every oppertunity I will try and convince people to close their eyes and to spend the money on Lithium now if you want a fit and forget install.

1 minute ago, Jaws said:

48 V , but only because it opens up more options for Lithium batteries.

Serioulsy like TTT and Plonkster will preach Victron at every oppertunity I will try and convince people to close their eyes and to spend the money on Lithium now if you want a fit and forget install.

yeah but in honesty i am already pushing my budget, and the equivalent lithium for my system is what like over 30k just on batteries?

5 minutes ago, Dex_ said:

yeah but in honesty i am already pushing my budget, and the equivalent lithium for my system is what like over 30k just on batteries?

start with a single 2.4 kWh Polyntech  , see how far that gets you for now....

Budget is always an issue, because I also want to say that if you plan to add solar than I wouldnt recommend an Axpert .......

If you only want an UPS type setup with no solar - Axper with a Lithium battery will work

If you want some return on the investment then you need solar with a Hybrid inverter.

Cheapest way to start out is probably a Goodwe with a Lithium battery (R20k + R15k)

Then you can start adding panels...