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Overloading an inverter


isetech
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A question with regards to overloading an inverter.

It seems to be a normal practise to install an inverter ... lets say a 5 kva with more than 25 amps of load connected to the inverter ... with a note ... if the power goes off just switch off some of the deivices and switch on the devices you want to run ... in most cases during the day when nobody is home the solar is charging the batteries and providing enough power for the 25 % load being consumed. 

What are the implications of doing this ... I see many installtions have 32 amp circuit breaker protection for a 5 kva unit ... will the inverter just go into overload ... trip and then reset if the paramete rfor auto reset is used? 

Lets say for example you have 5 aircons running ... the air fryer ... and a hand ful of lights and decide to run the kettle ... and the power switches off for load shedding.

From the inverter output ... in this specific case ... there are 5 plug circuits feed 14 plug points ... which have 5 aircons connected to the plug sockets ... all the plugs in the kitchen ... the gate ... all the lights in the house and more.

There is a 5 kva inverter with 3 sets of 4 panels to make up 12 in total ... I would think that during the day it is not such a big issue if its a sunny mid summer day ... however at night after 6 ... maybe not such a good idea. 

 

 

 

 

 

 

 

 

 

 

 

 

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40 minutes ago, isetech said:

What are the implications of doing this ... I see many installtions have 32 amp circuit breaker protection for a 5 kva unit ...

The breaker is basically there to protect the wiring, not the inverter.

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will the inverter just go into overload ... trip and then reset if the parameter for auto reset is used? 

Yes.

As for 5 air conditioners etc, perhaps you need two 5 kW inverters paralleled.

But you also need to consider the battery. A battery that can supply 10 kW continuously is usually at least 20 kWh in size, and that can get expensive.

You might decide that you don't need / can't afford that level of luxury when load shedding is on, and cut back loads. It means being aware of whether the utility power is on or not, what others are doing with loads, etc. I remember Chris Hobson's words for his family: "this thing is not a nuclear power plant!".

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@Coulomb has converted my thoughts into something comprehensible 🙂.

There are inverters which have 2 outputs, for essential and for non-essential loads and I'm guessing your aircons would join the non-essential output side and thus not contribute to power consumption/run when blackouts are rolling...

Which makes me think... load shedding, you are just a *load* to be shed, by Eksdom, a load of what, I wonder... this is where all in the position, to lighten the burden on Eksdom's load, should probably aim to not be a load anymore and disconnect from them instead...

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I busy working on a site which has this setup (I didnt install the system ... cleaning up and checking a few things).

I am waitng for the solar installer to produce a COC ... a visual check ... indicated that a more indepth investigation be carried out.

Simple things like sharp metal parts where the panel was cut to install wiring (no gommits installed) 

NO indicator lights on output (essential DB) and the labeling not clear.

Solar DC wires running in the same trunking to the sub DB's ... 1 trunking for all wiring ... battery/PV/input/output ... not even a 2 compartment. 

15 socket outlets on one circuit (basically the entire house) connected to to the inverter output ... my concern is the effect this will have on the inverter and the batteires (200amp flooded lead acid) 

My aim to is make sure that the installtion as a whole is tidy and reasonable safe (per SANS black book) ... if the customer decides to sell ... I dont have to issue a 5 page fault list worth 30 K before they can sell.

This is something I am incouraging all my customers to do ... after learning the hard way.

I had a customer attempt to sell their house ... I had made them aware of the mess and the illegal wiring (the COC they had received from the seller was non compliant) ... however they chose not to "fix the mess" at the time ... 6 years later the house was put on the market for sale ... as they were immigrating ... a request to issue a COC for the property was sent to me ... I replied to the email with the fault list attached from 6 years ago ... I had done when they moved in ... that's were the fight started. 

I was called all sorts of names and dragged through the shyte for months ... because I refused to issue a COC ... the customer couldnt understand why I hadnt just repaired all the problems over the years (at my cost) because I was their "electrician" .

How it works now ... even if one of my customers is going to rent (tenant) or rent out a property ... an inspection report is carried out and a list of any faults recorded with a quote for the repairs ... by doing this it also prevents any confusion when the tenant moves out ... especially in commercial or factory enviroments. 

 

 

 

 

 

 

 

 

 

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