Compliments of the season to the forum. 

My axpert 5/3000w pv/ 2x pylon us300 system produces on average 14kw/h per day.

The maximum pv I get is around 2400w during sunny weather. The maximum rises to 3100w in partly cloudy weather. 

My question is, can I install another 1000w of pv to lift my solar charging capability , even though my older Axpert can only take 3000w,? Does the Axpert ignore the extra Watts or will it damage the Inverter? 

Thanks 

Rob. 

 

29 minutes ago, RobG said:

Does the Axpert ignore the extra Watts or will it damage the Inverter? 

With an Axpert it is better to stay within specifications. I would not oversize the array with 1000 watt. 

The Axpert 5kva units that I am familiar with allows for 4000 Watt PV, what model do you have? If your inverter only allows for 3000 watts, your options however imo, to allow for more PV is as follows. 

1. Upgrade the inverter.
2. Add a second inverter in parallel and connect more PV to the second inverter. 
3. Or install a  Victron MPPT, with some more PV, configured to take care of the Charging, leaving the existing PV to take care of the loads.  

Thanks for the reply Jaco 

It's a 2015 Tescom branded Voltronic Axpert. The little Manual that comes with it states that pv array maximum is 3000w, 60A.

I'll check out the options you suggest. 

Kind regards 

Rob 

@RobG,

When i used the 5kva axpert, i had 3600w worth of panels on it. The same i'm running on the Infini 5kW V's today for the last 18 months. So you can do it, but the risk is on you.

23 hours ago, RobG said:

My question is, can I install another 1000w of pv to lift my solar charging capability , even though my older Axpert can only take 3000w,? Does the Axpert ignore the extra Watts or will it damage the Inverter? 

Lots of Axpert uses have installed 3.6kWp without any issues, the main concern is not exceeding the max MPPT input voltage. If you currently have 10x300Wp panels wired 2S5P then you can increase to 12x300Wp wired 2S6P, the MPPT will not accept input above 3kW.

10 minutes ago, pilotfish said:

Lots of Axpert uses have installed 3.6kWp without any issues, the main concern is not exceeding the max MPPT input voltage. If you currently have 10x300Wp panels wired 2S5P then you can increase to 12x300Wp wired 2S6P, the MPPT will not accept input above 3kW.

I've got 12x250w pv. 

I need to get another Inverter I reckon. 

11 minutes ago, RobG said:

I need to get another Inverter I reckon. 

That would be the best way forward if in the budget.

On 2018/12/26 at 12:49 PM, RobG said:

Compliments of the season to the forum. 

My axpert 5/3000w pv/ 2x pylon us300 system produces on average 14kw/h per day.

The maximum pv I get is around 2400w during sunny weather. The maximum rises to 3100w in partly cloudy weather. 

My question is, can I install another 1000w of pv to lift my solar charging capability , even though my older Axpert can only take 3000w,? Does the Axpert ignore the extra Watts or will it damage the Inverter? 

Thanks 

Rob. 

 

I presume your 3KW PV array is setup in 5 strings of 2 panels in series, so adding another string (i.e. 600W) would be fine. The MPPT will use the maximum available power, upto 3000W. I would put a 60A fuse on the PV input side to safeguard it. Put a 12A fuse on each PV string as well.

Thanks for the responses.

I've seen 55amps on cloudy days so pretty close to the 60A limit. 

If I theoretically add the newer Axpert 5.5 Kva 80A to my existing Axpert 60A, would that give me a usable 140A pv if I added another 4000w of pv?

Currently I have 12x250w panels. Can I add 300w panels to the array or would I need to stay with 250w panels? 

 

On 2018/12/27 at 9:30 AM, Sidewinder said:

i had 3600w worth of panels on it

 

On 2018/12/27 at 12:21 PM, pilotfish said:

Lots of Axpert uses have installed 3.6kWp without any issues

 

8 hours ago, SilverNodashi said:

so adding another string (i.e. 600W) would be fine

Rob seem like adding 600 watt should not be a problem according the above .

I do warn against doing the following.

8 hours ago, SilverNodashi said:

 as long as you stay below 145V input and 60A

The 60 amp rating of the mppt is the rating of the maximum current it can sent to the batterys. It is the Max output rating, not the max Input rating. If I do what is stated above and stay below the mentioned figures the sum would look like this. 

140Volt x 59Amps = 8260Watt input

lets say 2 panel in series and few strings in parallel.  

70 volt x 59 amps = 4130 watt input 

Both way over what the Manuel say its safe to do. 

 

11 minutes ago, RobG said:

Can I add 300w panels to the array or would I need to stay with 250w panels?

Try and use the same or at least a different make with the same specs if you cant get the same as you have and then add 2 x 250 watt (500 watt.)

Personally, I would stick to the specs in the manual, but others here feels its safe to add. so i guess you can add at your own risk. 

8 minutes ago, RobG said:

Thanks for the responses.

I've seen 55amps on cloudy days so pretty close to the 60A limit. 

If I theoretically add the newer Axpert 5.5 Kva 80A to my existing Axpert 60A, would that give me a usable 140A pv if I added another 4000w of pv?

Currently I have 12x250w panels. Can I add 300w panels to the array or would I need to stay with 250w panels? 

 

You can't parallel different size inverters. Assuming you have a 5KVA/4KW Axpert, you would need to get another 4KW Axpert to parallel connect them.

Then if you add more panels, each inverter would have it's own PV array. So, in theory you would have 140A worth of PV, but split between the two inverters, if that makes sense? Each inverter can take 3000W rated PV power, and safely have upto 3600W connected panels. You can use 300W panels on the new inverter

I want to clarify this matter, since it was brought to my attention that I gave the wrong advice.

A 60A fuse will ensure you stay before the current rating, but it won't blow if you go above the voltage rating. These inverters work better if you come as close to the upper voltage limits. 3x 250W solar panels in series would give you about 90V-100V, Voc, and 8-9A Isc depending on which brand you use.

4 strings would then give you about 32-36A current at say 90V.

Adding another string of 3 panels would add 750W to the mix, and up the current to about 40-44A.

Current / Ampere is used when needed, so the inverter will draw from it's "reserves" upto the 3000W max rating. Differently put, your house might have a 63A main switch but your kettle will only draw about 9A (2Kw element at 220V) when you boil water. It doesn't draw the full 63A. Likewise the inverter will only draw the necessary current it needs, upto 3000W. The current will vary as the voltages vary (the sun moves the whole time, and clouds may move in between, so the panel voltages vary the whole time.)

Hi SilverN

I want to clarify this matter, since it was brought to my attention that I gave the wrong advice.

My Inverter is the older 5Kva, which according to the manual has a maximum pv array of 3Kw

My ICC shows maximum pv of over 3.2Kw 55A on cloudy days at solar max. 

I'll try the suggestion of adding 2x250w panels as the first step. 

Wiring will be a bit interesting. 

Thanks for the help. 

Much appreciated. 

 

3 hours ago, RobG said:

Hi SilverN

I want to clarify this matter, since it was brought to my attention that I gave the wrong advice.

My Inverter is the older 5Kva, which according to the manual has a maximum pv array of 3Kw

My ICC shows maximum pv of over 3.2Kw 55A on cloudy days at solar max. 

I'll try the suggestion of adding 2x250w panels as the first step. 

Wiring will be a bit interesting. 

Thanks for the help. 

Much appreciated. 

 

How are your panels wired up right now, if you get 55A? 2 per series? If so, you would need to rewire them in 3 per series first. With 12 panels that would give you 4 strings with 3 panels per string.

Only then can you add more panels. If you add two more panels right now, with 55A on a cloudy day, you'll likely see 62A peak

On 2018/12/26 at 1:37 PM, Jaco de Jongh said:

With an Axpert it is better to stay within specifications. I would not oversize the array with 1000 watt. 

The Axpert 5kva units that I am familiar with allows for 4000 Watt PV, what model do you have? If your inverter only allows for 3000 watts, your options however imo, to allow for more PV is as follows. 

1. Upgrade the inverter.
2. Add a second inverter in parallel and connect more PV to the second inverter. 
3. Or install a  Victron MPPT, with some more PV, configured to take care of the Charging, leaving the existing PV to take care of the loads.  

Hi Jaco

It's been a while but getting closer to upgrading the system. 

How would I go about using the Victron charger scenario? 

You say the existing will handle the load and the extra pv will do the charging. The price of the victron charger and the Axpert 80A Inverter are similar. It seems a no brainer to add the victron then . 

What is the downside of this? 

Is it a simple set up or do things get complicated? 

Thanks for the input. 

Kind regards Rob 

a old'ish conversation (having a resurrection) but very relevant I think...

Think we do need to understand/split the workloads.

There is what's coming in from the panels (DC) and then going to the batteries to charge them, that's done by the Charge Controller (the going to batteries, the storing of energy)...and then

There is the inverting function, taking DC from battery and inverting to AC and providing to house.

How long it will take to charge batteries is based on source (number panels/configuration) and ability to take that and push to the batteries (defined by Charge Controller rating being able to take the Voltage and Ampage and output to batteries), the more batteries you have the longer it will take to charge with 5 panels, go to 10 panels and you can charge faster, but your Charge controller needs to be able to handle the V and A. 

As far as the Axpert Appliances are related, they are actually a Inverter and a Charge Controller build into the same frame, with the Charge controller's output matched to the Inverting capability. Easiest solution for you, get another exact same Axpert, parallel them, bring the panels into a bus bar where your batteries, panels and both inverters are connected o.

or ... Grey area...

How you would / could connect extra panels to a dedicated Charge Controller (ie victron SmartSolar/BlueSolar) which then connects to your batteries via bus bar, also connect to this bus bar is your current Axpert, which will only invert from batteries as much as it's been rated for. The panels connected to the Axpert, will provide energy either directly to the Inverter to go into your house, this amount based on the inverter rating, or send energy to Charge Controller to be pushed/stored into the batteries.

How you would get the dedicated Charge Controller and the build in Axpert to play nice together, on the charging of a shared battery bank, gets interesting.... both the Dedicated Charge Controller and  build in Axpert would need to be configured with the same Input/charge settings.

My take on things, sure I've got something wrong, sure one of the guys will correct me... heheheh

G

Thanks for the informative reply George. 

My concern going with adding a new exact same Axpert is, that the existing Axpert is 4 years old. Will I still be able to get the exact model that I have? It was bought and branded from Tescom who dropped all support of Axpert over 3 years ago. 

This way though will enable 6 KW of pv though. Going with a new 80A /4000w pv axpert is the other way. 

But I need another Pylontech US300 to give me the backup I need. (10.5KW total). I use around 1700w/Hr daily from 9-4 and around 450w for the rest of the night.

I run my post production audio suite from my home, so the day time usage is not a constant. When there's work I work. I have change over switches to mains for pool, kitchen, gate and the studio, so I can manually manage things as the clouds roll in. I also need to connect my 5.5Kw generator to charge and run the system if needed. 

Big plans, shallow pockets. 

What is the best cost effective solution? 

I would not use another brand MPPT with the Axpert inverter. In fact, don't mix MPPT's and inverter brands, for various reasons. Most manufacturers optimize their own equipment to work with itself. 

Can you get another, older inverter? Here and there people sell theirs as they upgrade, so shop around a bit on olx / junkmail / here / FB / etc. I might consider selling my 2015 model as well but it's worth more to me than what people are prepared to pay for it 2nd hand. It still works as good as it was when I first installed it. The fans don't give problems, and it doesn't give me issues so it's rock solid. 

 

On 2019/04/04 at 9:16 AM, SilverNodashi said:

Can you get another, older inverter? Here and there people sell theirs as they upgrade, so shop around a bit on olx / junkmail / here / FB / etc. I might consider selling my 2015 model as well but it's worth more to me than what people are prepared to pay for it 2nd hand. It still works as good as it was when I first installed it. The fans don't give problems, and it doesn't give me issues so it's rock solid. 

 

That  is an option. 

Would we be able to tell from Serial numbers if they are the same batch. And is the parallel cable available still for the older Axpert?

Why do you want another inverter? Just get another MPPT, connect the panels and away you go.

How would I get the existing built-in charge controller and the new one to work together. 

From earlier post

How you would get the dedicated Charge Controller and the build in Axpert to play nice together, on the charging of a shared battery bank, gets interesting.... both the Dedicated Charge Controller and  build in Axpert would need to be configured with the same Input/charge settings.

3 minutes ago, RobG said:

How you would get the dedicated Charge Controller and the build in Axpert to play nice together,

I have this situation. I found it best to set the other (non Axpert) charge controller to drop out at slightly lower voltages (both absorb and float) than the Axpert. Both settings are lower by a tenth of a volt or two (48 V system).

In the morning, they both work together to charge the battery. When the battery is some 90% charged, the second charge controller drops off, unless there is a big load or cloud and the battery voltage drops. Then it starts contributing again. Once the Axpert has done the last 10% or so of charge, it drops to float mode, trickle charging the battery and supplying all the small loads. When a larger load comes along, the battery voltage dips a few tenths of a volt, and the other charge controller starts contributing charge current.

It works pretty well for me. The only frustrating thing is on a cloudy or rainy day when I know that the battery will be lucky to get fully charged, is that period when only the Axpert is charging the battery, when in theory they both could. But it's really not significant. If I miss out on a few percent of SOC some days, it's no great loss. I haven't paid an electricity bill for well over a year. (I have a feed in tariff on a separate grid-feed system that balances the fixed connection charges, and most of the power I use for the oven and big air conditioner. )

All the suppliers say the old mks 5kva 60A is no longer available. 

So I have to get the new mks ll 5kw which can handle 4.5KW of pv. 

I have 12 x 250w panels in 3 strings and cannot get any more 250w panels. 

I can get 275w panels which would push total pv to 4575w, slightly higher than the maximum. Would the extra 75w create problems or would it be OK to use with the Axpert? 

13 hours ago, RobG said:

All the suppliers say the old mks 5kva 60A is no longer available. 

So I have to get the new mks ll 5kw which can handle 4.5KW of pv. 

I have 12 x 250w panels in 3 strings and cannot get any more 250w panels. 

I can get 275w panels which would push total pv to 4575w, slightly higher than the maximum. Would the extra 75w create problems or would it be OK to use with the Axpert? 

Not at all. You will hardly ever get 100% production so the extra few Watts help a bit. In fact, you can add about 20% more PV power as well.