Hi Guys I new here. 

I have just installed solar panels to my inverter.  

The inverter are getting power from the panels however I am not a charging current from the inverter when set to Solar first.

 

 

Inverter: RCT-AXPERT 3K

Solar Power 600W

System Voltage 24VDC

Max Solar Voltage (VOC) 

 

Battery: 2 x 12V Deep Cycle Gel Battery's in series for 24V

Solar panels

PSS SP-50P

PMax 50W

Vmp 2.87A

Voc  21.6V

Isc

 

 

Edited March 16, 20215 yr by riaanhar

Please display the sticker on the side of your inverter. That will tell you what the range of the pv input should be.

Looking at the pv input voltage as measured by the inverter, seems your pv input voltage is too low. How is your pv panels connected? If parallel, then you should try going 2S or even 3S, seeing your Voc is low, compared to regular 250W and larger panels. 

Thanks guys

That is correct the Inverter is rated at 30-66V DC. 

I have 24 panels available I have 6 panels in series x 4  and 2 each paralleled at the moment. I have only connoted the one set for testing. I am just worried of exceding the maximmum wattage the inverter can handel. 
Am I correct in that it does not matter if the pannels are in parralel or series you counted the wattage of each pannel togeter to give the wattage total. In this case if all 24 pannels are used 1200W. The inveter are rated at 600wmax at  PV input.

Will it be fine as long as I do not eceed the 66 VDC Or is it better to get a inverter with a bigger charge controler rated at 60A and PV max 1500W 

Many thanks for the feedback so far.     

 

Edited March 16, 20215 yr by riaanhar

4 hours ago, riaanhar said:

I have 24 panels available I have 6 panels in series x 4  and 2 each paralleled at the moment. I have only connoted the one set for testing. I am just worried of exceding the maximum wattage the inverter can handle.

It's also important not to exceed the 66 V max.

4 hours ago, riaanhar said:

Am I correct in that it does not matter if the panels are in parallel or series you counted the wattage of each panel together to give the wattage total.

You are correct in that the total maximum power available will be the panel power times the number of panels, IF the load is suitable. In this case, the panels' load is the solar charge controller, and it has a fairly restrictive voltage range. So that will determine how you connect the panels. In your case, you can probably just squeak under the limit with 3S.

Quote

In this case if all 24 panels are used 1200W. The inverter are rated at 600wmax at  PV input. Will it be fine as long as I do not exceed the 66 VDC Or is it better to get a inverter with a bigger charge controller rated at 60A and PV max 1500W 

1200W is 100% overload; generally 15-25% overload is recommended. So yes, it would be better to replace the inverter with one with a larger solar controller, OR you could add an external MPPT for one half of the panels. This MPPT would connect directly to the battery. Hopefully the external MPPT will allow more panel power than the RCT inverter-charger. It's not ideal, but workable, and likely far less hassle than replacing the whole inverter.

However, you may well have a problem with your small battery. You have used the AGM battery type (the default). If they are say 100 Ah, then usually you can only charge them safely at a maximum of 15% of the amp-hour rating, i.e. 15 A. That's 375 W. If you battery modules are 200 Ah each, then that's 750 W. So you probably can't use all your panel power with your small system anyway.

If you have 200 Ah battery modules, then you could add a small 150 W MPPT, or say 250 W and limit the inverter's solar charger controller to 500 W of battery charge power (20 A charge current) if that's possible. That would get you maximum use of your panels, even though you'll never get 1200 W from the system. The extra nominal panel power will still be handy for cloudy weather and early/late in the day.

Replacing the inverter with one that has a bigger MPPT does have some advantages, though. For example, even though your battery will be limited to a small fraction of the MPPT's rated power, the rest can be used to power loads during the day. You can't do that with an external MPPT, because it's not aware of the power that the loads are using.

Many thanks guys for the help. Apologies for not replying earlier the day was just hectic.

 

Based on the information provided I think it is best to replace the inverter. The inverter is already over 6 years old and had paid for it self many times over.

My batteries are 2 x 12V 210AH Gel batteries in series for the 24V requirement. 

 

Sorry I have my panel configuration posted above mixed up. 

To clarify currently I have 4 stings of 6 panels in parallel. Then I have 2 of the 4 strings connected in series. The other 2 strings are not connected yet.

So if I want to utilize all my panels with the bigger inverter I assume a 3S8P configuration should work. Should give me around 60V @ 1200W.

The inverter I am looking at is a re-branded Axpert inverter with the following specks.

3kVA/2.4kW/24V Inverter

Built in:

• 60A MPPT charge controller (from PV) 

• Inverter charger (grid to battery, solar to battery)

• Bypass for grid to usage

Max Watt Output:

• Continuous: 2.4kW

• Surge (5 seconds): 4.8kW

Charging Source Settings:

• Solar first, solar only, grid only- Can be set

• Solar only: 60A (maximum)

• Grid only: up to 30A

 

Expansion: Single Inverter

• PV Panels minimum: 500W

• PV Panels maximum: 1500W

• Batteries minimum: 2 x 100Ah 12V in series

• Peak Efficiency: 90%

• No Load Power Consumption: <25watt

 

Looks like the PV Array MPPT voltage range are the same 30~66V

With my current set-up my average load usage are normally below 25% and will rarely max out at around 40%.

On average I get about 8hrs of battery use with an extensive power outage with normal use patterns. So in-terms of inverter specks I do not think need anything bigger that a 3kva solution.

 

I don’t know if you guys have any other suggestions or recommendations?

 

Many thanks

17 hours ago, riaanhar said:

So if I want to utilize all my panels with the bigger inverter I assume a 3S8P configuration should work.

I'm a bit uneasy about 3S, especially in winter. You say the Voc is 21.6 V; that's presumably at 25°C. I find the voltage rises about 7% at 0°C, that would be 21.6 x 1.07 = 23.1 V; 3S would make that 69.3 V. I don't know the small SCCs, but if they're like the larger 145 V max models, maximum solar production will be 0 W (no power at all) at the upper limit of the PV range. So 69 V will be testing the limits of endurance, and you'll likely get reduced output above about 60 V (wild guess). Other forum readers here have found that bucking from near the upper limit of the voltage range (66 V → 25 V) causes the SCC to get hot and limit power due to temperature as well as voltage.

You seem to be saying that your panels are already all configured 2S 6P, so why not wire it 2S 12P? You'll need a lot of fuses to protect all those small panels. It might also be difficult to find fuses small enough to do any good. 1200 W is still plenty power to start a roof fire.

Have you considered a 5 kW 48 V model with an even larger solar charge controller? There seem to be fewer choices for 24 V lithium batteries than 48 V ones.

Hello gents. 

 

I have a 3kva RCT inverter with 2x 100AH batteries on.  Works perfect.  

 

I now want to add a 180ah solar panel.  I did that, but it does not seem that the inverter picks up that a solar panel is connected.  are there any settings that need to change so that the inverter sees the solar panel?

 

 

On 2022/12/08 at 11:32 AM, Fillistyn said:

Hello gents. 

 

I have a 3kva RCT inverter with 2x 100AH batteries on.  Works perfect.  

 

I now want to add a 180ah solar panel.  I did that, but it does not seem that the inverter picks up that a solar panel is connected.  are there any settings that need to change so that the inverter sees the solar panel?

Hi Fillistyn, did you make a typo for the solar panel spec, should it be 180W? What are the other specs? Voc, Vmp? It seems like you want to add 1 panel, but that is possibly not enough voltage for the SCC to initialize. You should have a voltage range for the solar charge controller on the side of the inverter, you need to be above the minimum for the inverter to 'see' the panel. You possibly need more panels in series if they are low voltage.

On 2022/12/08 at 11:32 AM, Fillistyn said:

Hello gents. 

 

I have a 3kva RCT inverter with 2x 100AH batteries on.  Works perfect.  

 

I now want to add a 180ah solar panel.  I did that, but it does not seem that the inverter picks up that a solar panel is connected.  are there any settings that need to change so that the inverter sees the solar panel?

 

 

As the inverter was used from grid only the 1st thing I will do is to check setting 16 if it is not set to Utl. Try it with setting CSO or OSO. 

You might find there is good reason why Axpert indicate a 500W PV. The 25W own consumption worked for 24hrs you might find all the PV is used for self consumption. You will find saving from grid use but not much power available for charging a battery. 

The above is based on using a 180W panel. 

If the panel has a Vmp of around 35V it should provide so power from solar after allowing solar to charge and not grid as the only charger.