Help with solar pv polarity

[marconi]

There remains the question about whether to continue with floating ac lines viz L1 and L2 or whether to connect one L2 to local earth to produce L and N. As this home is off-grid and not serviced by a mains electricity supply the first step I think is to find out what the Portuguese wiring regulations say for sites with two sources of non-grid mains supply. I don’t get involved much with foreign wiring systems because I don’t know what I don’t know.

There will be others in the EF who can advise you should you wish. If most dwellings are earthed neutral then I would see advantage in making this place the same to avoid a surprise to electricians in the future and the use of single pole protection and switching accessories. Most home appliances assume LN not floating L1 and L2. The thinking required is where and how to make the L2 of the gennie and the inverter into an N. Some signage would be needed.

I stand ready to assist further with the polarity query.

Happy New Year. Please follow up and pictures are always enjoyed.

 

[Algarve Sparky]

Thank you again for input, as it happens I have a call back tomorrow as the client has a further issue arisen over the New year holiday.

His message reads

"Hi Jeff,
Have a strange issue when the geni is on and the inverter panel is show the two 230v inputs, as we use more power the 230v starts to reduce going as far down as 189v and then the geni built in trip activates "

Not sure what he means exactly so will go and look for myself and report back here what I find.

Thanks

 

[pc1966]

That sounds a lot like the generator is overloaded so its volts are dropping, but it might also be some feed-through limit of the inverter if it is acting like a UPS (i.e. input from PV and/or generator goes to battery first, and from there is converted to AC output).

Do they have any metering to show what demands they are placing on the system?

 

[marconi]

https://gbc-solino.cz/wp-content/uploads/2020/03/Axpert-VM-III_manual-20190201.pdf

(Re #18: The inverter display can show 230V ac power output).

When the inverter uses the utility input - in this case fed from the gennie - it is in bypass mode such that the utility input is connected to the output by a fast transfer switch. You can tell the power inout/output mode of the inverter by looking at the state of the LED lights and referring to page 13 of the inverter manual at link above.

The total power drawn from the gennie is not just the 230V ac output load; it also includes battery charging if this has been selected using the general setting - see page 16 onwards.

Please confirm first what is the power output priority - PROGRAM 1 page 16. I expect it to be SbU.

Now back to battery charging. The maximum utility (ie gennie derived) charging current can be preset - see page 18. If for example the maximum utlity charging current is 40A then the power required from the generator is 48V x 40 = 1920W or nearly 2kW. Depending on the state of the battery's charge, there may be times when the remaining power available from say a 2.8kVA gennie for the house load is only 2.8 - 2 = 0.8kW. As the battery charger progresses through its charging routine the charging current will reduce over time until it is only a nominal trickle current - then the full output of the gennie is available to power the house load. The gennie can the n be easily overworked if the battery is in a low state and the house load is high at the same time.

When you visit next, find out the kVA of the gennie and then have a look at PROGRAM 11 see page 18 and discover the maximum utility charging current. Also look at PROGRAM 2 page 16 to discover what is the total solar plus utility charging current limit.

What you can do to free up more power from the gennie is reduce the maximum utility charging current . Of course the battery will take longer to charge. In the applications I have used hybrid inverter with 3.4kVA gennie input I selected a charging current to produce 0.5kW - in your case a current of 500/50 = 10A - for a maximum load power of circa 1.5kW and a margin of 1.4kW to deal with fridge/freezer starts.

I hope this makes some sense. Please provide some numbers for the charge currents if you wish further help and gennie kVA and type.

 

[Algarve Sparky]

Sorry for slow reply, been flat out with installs, the generator problem has been resolved, the two core remote cable to start the genny automatically when low on sun load and low battery had an issue ( pulled in an underground tube 30 metres from the house ).

Still ongoing issues but not back on site till next month, the solar company still will not come back !