Axpert invertors

Hi all, long thread :)

I'd like to setup an Axpert 5kVa with PV to generate in the region of 8kWh/day. I'd only add battery's as a way to use some excess generated power at night. I am trying to get a short as possible payback period. UPS type functionality during load shedding is less important.

1. Am I correct that insufficient power generated from PV will cause the Axpert to rely solely on the grid during that time?
2. What happens when the total required load is more than the Axpert is rated for? So someone switches on an oven for instance. Do you have to isolate circuits so that the total load never exceeds the Axperts max or does it just happily bypass to grid?

Thanks
 
knoop said:
Hi all, long thread :)

I'd like to setup an Axpert 5kVa with PV to generate in the region of 8kWh/day. I'd only add battery's as a way to use some excess generated power at night. I am trying to get a short as possible payback period. UPS type functionality during load shedding is less important.

1. Am I correct that insufficient power generated from PV will cause the Axpert to rely solely on the grid during that time?
2. What happens when the total required load is more than the Axpert is rated for? So someone switches on an oven for instance. Do you have to isolate circuits so that the total load never exceeds the Axperts max or does it just happily bypass to grid?

Thanks
Click to expand...

1. Yes, since the Axpert is not a true hybrid, it cannot combine PV and grid to supply the load.
2. The Axpert will trip after a few seconds when it is overloaded. One solution is to not run circuits like the stove/geyser etc. which will cause an overload, through the Axpert.
 
knoop said:
Hi all, long thread :)

I'd like to setup an Axpert 5kVa with PV to generate in the region of 8kWh/day. I'd only add battery's as a way to use some excess generated power at night. I am trying to get a short as possible payback period. UPS type functionality during load shedding is less important.

1. Am I correct that insufficient power generated from PV will cause the Axpert to rely solely on the grid during that time?
2. What happens when the total required load is more than the Axpert is rated for? So someone switches on an oven for instance. Do you have to isolate circuits so that the total load never exceeds the Axperts max or does it just happily bypass to grid?

Thanks
Click to expand...

The AC to DC charger uses the same internal circuitry as the DC to AC inverter, so you can't pull in Eskom power unless you're in bypass mode.
 
superdiy said:
1. Yes, since the Axpert is not a true hybrid, it cannot combine PV and grid to supply the load.
2. The Axpert will trip after a few seconds when it is overloaded. One solution is to not run circuits like the stove/geyser etc. which will cause an overload, through the Axpert.
Click to expand...
Right, then this requires a bit of planning. The trick is to get the Axpert on a circuit that won't overload it and draws under what the PV can generate. At the same the circuit should draw a load as close as possible to the PV max. (Shorten payback period).
 
superdiy said:
I really doubt it. The inverter is however designed that the two don't work at the same time though.
Click to expand...

It is the same circuitry. APC originally designed such a circuit for a low frequency inverter: http://www.google.com/patents/US5302858

This was obviously adapted such that the boost stage can run in reverse.

It is in theory possible, you still just need an extra set of diodes on the inverter stage and boost stage to run the whole thing in reverse.

The lack of an extra transformer should have made it plainly obvious that it is the same circuit.
 
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Another thing - can the Axpert 5kVa operate with PV only - NO battery's attached?
 
knoop said:
Another thing - can the Axpert 5kVa operate with PV only - NO battery's attached?
Click to expand...

No. There is a relay on the Axpert that is activated by the input power from the battery. If that relay is off it won't even turn on.

So the input power wires go through a relay, that relay is turned on by battery power. No battery power = Axpert doesn't even acknowledge the existence of utility power.

Same as APC UPS (they really did copy a lot of ideas from them :p ).

At least that was the case with mine.

EDIT: Actually PV may work, I wonder. Since the PV is in parallel with the battery connectors. There are several reasons you shouldn't do this however. One of them being ripple current and over and under voltage. In general just a bad idea.
 
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knoop said:
@Gnome thank you.
Click to expand...

The Axpert is not the right inverter for you by the sounds of it.

Th Axpert is an UPS with solar input.

You will be rather disappointed in the Axpert if you think there is going to be any kind of "payback" with solar panels.

Rather look at hybrids like the InfiniSolar if that is what you are planning.

But as a load shedding buster the Axpert is the best band for bucks by far.
 
scottwday said:
Just don't use these battery isolators. They're cheap and easily available but they suck. There's only a little spring to separate the contacts so it easily welds itself closed circuit.
Click to expand...

I've just received my Mecer branded Axpert 5kVA inverter. Was quite surprised to see that it already has the parallel connection board installed. Always thought it was an add-on. I've followed this thread for some time now and have learned a lot.

I need to get the DC side sorted out before the electrician gets involved to make changes to my DB. As I understand it I either need to install a 2-pole 100A DC circuit breaker or a 2-pole isolator with fuses rated for 100A and ±60V DC. Can anyone recommend an affordable solution or a supplier in the Western Cape?

The only DC circuit breakers I could find rated for 100A was the QDC range from CBI. I don't have pricing, but it looks like it uses a 2P in parallel to achieve a 100A rating. What I don't understand is why the data sheet shows a minimum current rating of 60A for the 80V DC model and 30A for the 125V DC model. Does it matter? Maximum current rating for both is 100A. Thinking that it would probably be excessively expensive I decided to investigate the "fuse and isolator" option.

As pointed out earlier in this thread, the fuses from Outdoor Warehouse are only rated for 32V, so will only work for 24V systems. I came across the following fuses and holder on RS-Electronics rated for 80V and 100A

Holder: http://za.rs-online.com/web/p/base-mount-fuse-holders/3809923/
Fuse: http://za.rs-online.com/web/p/automotive-fuses/2260866/

R67.82 for the fuse I can live with, but R300.17 for the holder is a bit much.

Do I need a fuse on + and - or will one on + be sufficient?
Do I really need the holder or can I just clamp it inline?

I then struggled to find isolators that are rated for DC (always looks like AC rating). I also had a look at another battery isolator from Switches International. Rated 48V and 300A.
http://www.switches.co.za/product/battery-switches/batt-1559/
Any comment on suitability or should I look elsewhere?

So after several days of reading and research I've made very little progress. Any assistance will be much appreciated
 
BosH said:
RS Expensiveness
Click to expand...

You can try ACDC, they sell 22x58 100A fuses for R25
Single DIN mount fuse holder is R135, dual holder is R274
I have my fuse holder in a small DB board mounted under the inverter, it looks quite neat, and those fuse holders can also act as an isolator in an emergency. EDIT: You will want a proper isolator as well though.
http://www.acdc.co.za/getPage.php?page=165
 
BosH said:
Do I need a fuse on + and - or will one on + be sufficient?
Do I really need the holder or can I just clamp it inline?
Click to expand...

Only required on the + side. Won't be much use on the - side. Use a fuse holder, if the fuse blows hot it can shatter (the glass type), the fuse holder will provide a layer of physical protection and will allow it to be held in place securely and changed easily.
 
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scottwday said:
You can try ACDC, they sell 22x58 100A fuses for R25
Single DIN mount fuse holder is R135, dual holder is R274
Click to expand...

Thanks for the info.
How do I know if the holder and fuse can be used for DC? Items G-231 and G-232 is only rated for 690VAC
The DC fuse holder on the same page, item 211PV, is rated for 1000VDC, but only 32A. Not suitable.
 
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BosH said:
Thanks for the info. How do I know if the holder and fuse is can be used for DC? Items G-231 and G-232 is only rated for 690VAC
The DC fuse holder on the same page, item 211PV, is rated for 1000VDC, but only 32A. Not suitable.
Click to expand...

I'm using a GAVE 231 fuseholder, it's got a thermal rating of 125A, so that's DC or RMS AC. AC or DC doesn't matter for normal fuses. EDIT: It doesn't matter for current, high voltage DC will need special treatment.
http://www.gave.com/international/en/featured/akb-fuseholders.php
 
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Jaws677 said:
The Axpert is not the right inverter for you by the sounds of it.

Th Axpert is an UPS with solar input.

You will be rather disappointed in the Axpert if you think there is going to be any kind of "payback" with solar panels.

Rather look at hybrids like the InfiniSolar if that is what you are planning.

But as a load shedding buster the Axpert is the best band for bucks by far.
Click to expand...

+1
 
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