How much loss between panels and load?

[Mattb4]

Does anyone have a good rule of thumb number that can be used for estimating the standard loss for a solar panel power setup, wires, fuses/breakers, connectors SCC, battery charge in versus amount out, Inverter in versus out? I realize that it is dependent on the installation and components (longer wire runs, more or less efficient inverter and such) but it would be handy to know if there is some approximate like the 75% rule of thumb a solar panel has for rated to delivered watts.

As it is it almost seems like you have to build the thing before you really know what you are getting.

Example: For every 100 watts solar available in you can get 80 or 90 watts to power the load.

 

[JRH]

Does anyone have a good rule of thumb number that can be used for estimating the standard loss for a solar panel power setup, wires, fuses/breakers, connectors SCC, battery charge in versus amount out, Inverter in versus out? I realize that it is dependent on the installation and components (longer wire runs, more or less efficient inverter and such) but it would be handy to know if there is some approximate like the 75% rule of thumb a solar panel has for rated to delivered watts.

As it is it almost seems like you have to build the thing before you really know what you are getting.

Example: For every 100 watts solar available in you can get 80 or 90 watts to power the load.

You Said “ As it is it almost seems like you have to build the thing before you really know what you are getting.”

i would say this pretty true about solar systems. It also sounds like the path both of my marriages followed..my next venture in that area will be a AIO Tesla BOT, with a minimum performance profile spelled out ,and a good warranty.

Jim.

 

[Mattb4]

Women that come with a Warranty? I think I would need to see the small print.

 

[BradCagle]

Well all different makes/models of equipment have different efficiencies/ losses , etc.

But spending as much time on this as I have, I have found:
75% of the rated power is a good avg for solar panels
MPPT charge controllers 95% is a good avg efficiency
Good sine wave Inverters around 90% - 95% efficient

This is provided you're using decent quality components.

 

[OffGridInTheCity]

I have a 13kw PV -> Midnite Classic 150 Charge Controllers -> Lithium-ion batteries -> AIMS Inverters -> Load.
In a typical year, the Midnite's report 18,000kwh PV coming in (would not include wire loss) and cheap Amazon power meters on the AIMS output report 15,000kwh. 15,000 /18,000 = 83% useable or 17% loss yearly average. Add 2% for PV wire loss before it gets to the Midnites and I have an estimate of 19% yearly average loss.

The monthly average varies depending on Inverter load (efficiency) Here's historical data by monthly average. **Add 2% loss for PV wire.




Some facts:
The Midnite Classic specs say 98% MPPT efficiency - 2% loss. https://cdn.shopify.com/s/files/1/0...c-150-200-250-Charge-Controlers-Datasheet.pdf
The AIMS 12,000w inverters say 88% peak - at least 12% loss. https://www.aimscorp.net/12000-Watt-Inverter-Charger-48-volt-120-240vac.html
Lithium-ion charge/discharge? This article says ~5% but at 40% DOD let's say 2% https://www.large.net/news/8bu43pr.html

Biggest unknowns in my system:
- Accuracy of PV kwh incoming and kwh of consumption - the numbers are only as good as the measuring equipment, especially the cheap Amazon power meters.
- Lithium-ion battery bank charge/discharge losses - have no idea!

To recap - something like this:
PV wire(2%) --> Charge Controller MPPT(2%) ----> battery charge/discharge(2%) ---> Inverter DC-AC(13%) ---> load.

 

[niktak11]

I have a 13kw PV -> Midnite Classic 150 Charge Controllers -> Lithium-ion batteries -> AIMS Inverters -> Load.
In a typical year, the Midnite's report 18,000kwh PV coming in (would not include wire loss) and cheap Amazon power meters on the AIMS output report 15,000kwh. 15,000 /18,000 = 83% useable or 17% loss yearly average. Add 2% for PV wire loss before it gets to the Midnites and I have an estimate of 19% yearly average loss.

The monthly average varies depending on Inverter load (efficiency) Here's historical data by monthly average. **Add 2% loss for PV wire.
View attachment 104025



Some facts:
The Midnite Classic specs say 98% MPPT efficiency - 2% loss. https://cdn.shopify.com/s/files/1/0...c-150-200-250-Charge-Controlers-Datasheet.pdf
The AIMS 12,000w inverters say 88% peak - at least 12% loss. https://www.aimscorp.net/12000-Watt-Inverter-Charger-48-volt-120-240vac.html
Lithium-ion charge/discharge? This article says ~5% but at 40% DOD let's say 2% https://www.large.net/news/8bu43pr.html

Biggest unknowns in my system:
- Accuracy of PV kwh incoming and kwh of consumption - the numbers are only as good as the measuring equipment, especially the cheap Amazon power meters.
- Lithium-ion battery bank charge/discharge losses - have no idea!

To recap - something like this:
PV wire(2%) --> Charge Controller MPPT(2%) ----> battery charge/discharge(2%) ---> Inverter DC-AC(13%) ---> load.

This is why I went with a high frequency inverter for my house system. ~97% inverter efficiency is much easier to stomach.

 

[Warpspeed]

This is like saying I am being given fee money, but I am only getting 75% and I am really pissed.
Nobody gets 100%, I am getting what everyone else gets, but I am still really pissed.

Pretty funny actually..............

 

[robby]

@OffGridInTheCity gave you a good way of calculating it.
The approx number will vary significantly depending on the inverter, panels and wiring. Added into the mix is that manufacture inverter efficiency numbers depend on the load you are powering.
They are rated on a curve and the advertised number is typically at the sweet spot. If I remember correctly it’s something like 40-50% of rated output is the sweet spot. So even a 97% rating may be 92% at 80% of the rated load.

 

[x98myers7]

PVwatt estimator has 14% by default

I've heard 20% is the best "rule"

 

[Mattb4]

This is like saying I am being given fee money, but I am only getting 75% and I am really pissed.
Nobody gets 100%, I am getting what everyone else gets, but I am still really pissed.

Pretty funny actually..............

Actually no. The sun is free but after that everything else costs.

Understanding what those costs are is important if you want to achieve anything. Say you want to cool your home. If you do not buy a sufficient sized A/C unit it will not happen. Or for that matter if you fail to allow for the fact that your home has no insulation when you run out to buy a A/C system.

TANSTAAFL

 

[Mattb4]

@OffGridInTheCity gave you a good way of calculating it.
The approx number will vary significantly depending on the inverter, panels and wiring. Added into the mix is that manufacture inverter efficiency numbers depend on the load you are powering.
They are rated on a curve and the advertised number is typically at the sweet spot. If I remember correctly it’s something like 40-50% of rated output is the sweet spot. So even a 97% rating may be 92% at 80% of the rated load.

Ah yes ratings. You have touched on another aspect to keep in mind. Manufacturer ratings are not something you can take to the bank.

 

[hyberlut]

Besides actual inefficiencies, don't forget the power used by devices used in the system. My Renogy 2000W inverter uses 24 watts if it is turned on, regardless of whether or not it's powering something connected to one of the AC outlets. For a big system with plenty of panels and battery, no big deal, but for a tiny camp trailer like ours with too few panels and battery storage, those 24w add up, because it's on 24/7. Our 30A SCC uses only about 0.1 watt. Most other devices (depending on the model) like charge controllers and bluetooth and battery monitors don't use much energy at all. For the Renogy devices, 0.05 to 0.1W each device.

Generally speaking, the bigger the inverter, the bigger the idle power use. So going with as small of an inverter as you need will save your battery if you have an underpowered system like mine. The 1000W inverter uses only 12W, half of what the 2000W uses. I think I saw a 5000W inverter the other day that uses 45W...that's 1080Wh per 24 hours (90Ah on a 12v system), not even actually powering anything useful (except the inverter's own internal use).

 

[timselectric]

Does anyone have a good rule of thumb number that can be used for estimating the standard loss for a solar panel power setup, wires, fuses/breakers, connectors SCC, battery charge in versus amount out, Inverter in versus out? I realize that it is dependent on the installation and components (longer wire runs, more or less efficient inverter and such) but it would be handy to know if there is some approximate like the 75% rule of thumb a solar panel has for rated to delivered watts.

As it is it almost seems like you have to build the thing before you really know what you are getting.

Example: For every 100 watts solar available in you can get 80 or 90 watts to power the load.

Figure on 60%, and hopefully it will be better.