I have a 5.6 kW solar array installed with a 5.12 kW battery. However, by mistake installer put in a 8kW inverter instead of a 5 kW inverter. I am not planning on adding more panels. The installer agreed to correct their mistake and replace it for the 5 kW inverter. Should I replace it or leave 8 kW inverter in place? Does oversized inverter produce less energy than a matching inverter ir I shouldn’t worry about it?

Why would you reduce the size of the inverter, leave at is, you have 8 Kw of power, possibly enough to feed your all house. in a nice sunny day, you can power your geyser, microwave, kettle and more at the same time. 

Shouldn't be an issue to keep the 8kw. It gives you more headroom should your power usage change in future

You can never have too much power 🙂 

 

No problem as long as you are not going to use all the power the 8kw can provide and discharge the battery real quick. 

Edited February 4, 20233 yr by Scorp007

An 8kW inverter will have slightly higher own consumption than a 5kW inverter. I guess it could be a 100W or so. This is insignificant against the benefits of a larger inverter and if you manage your loads.

If its the same brand there's no reason to downgrade, other than the fact that you didn't actually pay for it.

What model is it?

 

8kW inverter might consume a little bit more power but definitely worth the upgrade.

 

Off topic: you have a 5kWh battery, not a 5kW battery.

Also running the 8kw at much less than its rating is good. Basically not pushing it's limits. 

 

Also future proof... Now you can add more panels without needing to change inverter.

Installer is happy as Larry as basically he will swop the 8 for a 5 at the price of the 8...

 

The problem is that in the meantime, the idle consumption will be about 8/5 higher. That might or might not make much difference depending on your circumstances.

26 minutes ago, Coulomb said:

The problem is that in the meantime, the idle consumption will be about 8/5 higher. That might or might not make much difference depending on your circumstances.

What would the difference be in idle consumption? 

Around 40W?

2 hours ago, archer327 said:

I have a 5.6 kW solar array installed with a 5.12 kW battery. However, by mistake installer put in a 8kW inverter instead of a 5 kW inverter. I am not planning on adding more panels. The installer agreed to correct their mistake and replace it for the 5 kW inverter. Should I replace it or leave 8 kW inverter in place? Does oversized inverter produce less energy than a matching inverter ir I shouldn’t worry about it?

I do not see an issue provided that the installer has set the correct battery charge / discharge current settings in the inverter. Will also allow you a higher pass through current when grid power is available.

Edited February 4, 20233 yr by Peter V

59 minutes ago, Dylboy said:

Also running the 8kw at much less than its rating is good. Basically not pushing it's limits. 

 

Also future proof... Now you can add more panels without needing to change inverter.

Installer is happy as Larry as basically he will swop the 8 for a 5 at the price of the 8...

 

To an extent.

You need to consider the efficiency curve of the specific inverter.

You're highest efficiency sits around 30-50% load

In some rare cases, if you really oversize your inverter and your load is low you can waste quite a bit of battery storage

4 hours ago, jeddles said:

To an extent.

You need to consider the efficiency curve of the specific inverter.

You're highest efficiency sits around 30-50% load

In some rare cases, if you really oversize your inverter and your load is low you can waste quite a bit of battery storage

Both the 8kW and the 5kW inverters have the same efficiency rating of 97.6%.

Inefficiencies are caused by loss due to heat and self consumption.

My 8kW unit uses between 75Wh and 80Wh self consumption. I have a 5kW unit at a rental property that uses between 60Wh and 65Wh self consumption.  This difference is very small.

The 8kW unit operates at consistently lower temperatures compared to the 5kW unit on both the DC and the AC bus thanks to the fans on the 8kW unit. The difference is mostly hovering around 20 degrees Celsius on you average Cape Town summary day which in my mind will cause the 8kW unit to be more efficient than the 5kW unit in summer with this being reversed in winter.

 

Edited February 4, 20233 yr by I84RiS

Don't worry at all , it's like if ur inverter is 5kw while ur consumption is 1 or 2 KW . The most important how will he arranged the 5.6kw panel array to fit on 2 mppt's of 8kw hyprid inverter . 

22 hours ago, archer327 said:

Should I replace it or leave 8 kW inverter in place?

If the "mistake" has no cost implications on your part then accept the 8kW inverter with open arms. It's like getting a Toyota Hilux 4x4 double-cab in place of a Toyota Corolla even though you'll not be carrying anything in the cargo bay.

22 hours ago, archer327 said:

Does oversized inverter produce less energy than a matching inverter

Not at all. The inverter power rating (kW) does not have to be close to the peak panel power (kWp) or the battery capacity (kWh). The maximum DC input power from solar panels is limited by the MPPT controller while the battery capacity purely depends on the expected run-time on battery mode.

 

Quote

or I shouldn’t worry about it?

The only thing to watch is your battery's maximum discharge current. Assuming your 5.12kWh battery is capable of 100A continuous discharge current then just don't add loads greater than 100A * 50V = 5kW on the 8kW inverter as the single battery would not discharge sufficient amperage for 8kW output without tripping the BMS or even voiding the warranty as is the case with some battery brands.

 

Edited February 5, 20233 yr by Kilowatt Power
Additional clarity

18 hours ago, Scorp007 said:

No problem as long as you are not going to use all the power the 8kw can provide and discharge the battery real quick. 

As @archer327only has a 5kw battery, he probably won't be able to pull 8kw from his batteries as the BMS will trip out

Assuming he has a 1C battery, the battery would only be able to produce 5kw of power.

Depends on the make of battery, some batteries at 0.5C i.e. 2.5kw of power continuous. 

I don't think it would be an issue, if your battery communicates with the inverter then it will limit power draw from the battery to protect it.

You are posting this question in multiple locations @archer327, rather stick with one thread 

1 hour ago, Sc00bs said:

You are posting this question in multiple locations @archer327, rather stick with one thread 

Mods have magically managed to merge most of them. 😎 

14 hours ago, Riyad179 said:

Don't worry at all , it's like if ur inverter is 5kw while ur consumption is 1 or 2 KW . The most important how will he arranged the 5.6kw panel array to fit on 2 mppt's of 8kw hyprid inverter . 

There is no worry on how to arrange the 5.6kw array as both use the same inputs and both have 2xMPPTs. No need for any change. 

The 8kW can just accept more panels and also at a higher current. 

On 2023/02/05 at 12:12 AM, Scorp007 said:

What would the difference be in idle consumption? 

Around 40W?

I would guess closer to 30 W. Just based on ratios.

Many thanks to all for your replies. I’ll then leave the inverter as it is and it’s been no extra cost to me because of the company’s mix up. So far everything is running smoothly, might just add another battery. The make is Sunsynk ECCO hybrid inverter with the matching battery by the way.