What does a xx kilowatt system mean?

[corn18]

I looked in the FAQ and could not find the answer to my basic question. I feel stupid reading all the threads saying xx kw system and not understanding exactly what that means.

My system on my RV (5th wheel):

800W solar (2S x 2 each with its own 100/40 MPPT SCC)
4,944 Kwh LiFePO4 batteries (2x206 Ah @ 12V)
1 x 2000W 12V inverter
1 x 1200W 12V inverter

So, how should I describe my system? Is it the AC capability?

 

[Dzl]

It doesn't mean anything really without further context. Probably most people that state xx kW system are referring to their PV array size (especially in the context of a home or structure), some others are referring to their inverter's max power, and still others are confusing and kW and kWh and are referring to the size of their battery bank, and a few others bought some form of all-in-one and are referring to whatever it says on the top line of the label/marketing material

In my eyes, its best to always qualify what you are referring to and use proper units. So much of the confusion here stems from people not using the right units, or not giving enough detail.

As to your system, the way you listed it is fine, better than saying 'I have an xx kW system.' The only thing I would change is instead of saying 2 x 206Ah SOK batteries, you should state xx Ah @ xx voltage (or just state the kWh). For instance 412Ah @ 12V or 206Ah @ 24V battery bank. And you could simplify 4 x 200W solar into '800W solar array' or (if you want to give more detail) '800W solar array in an xSxP configuration' (where xS is number of panels in series, xP is number of parallel strings).

 

[FilterGuy]

On traditional grid-tie, no-battery solar systems it is the rated KW of the solar array. (This also happens to be about the same as the inverter output) Note: Output of the inverter at normal operating conditions would be a more honest number, but salesmen like to use the largest number they can get away with

Once the system gets batteries, it gets a lot murkier. I have seen posts that say xxKW system referring to the panel wattage and I have seen posts say xxKW system referring to Inverter power output. Consequently, I try to explicitly state what I am referring to. (I have seen some of my old posts where I was not explicit.... so I am clearly not diligent enough)

 

[Don B. Cilly]

It doesn't really mean... much.
What you have: 212 Ah LFP batteries. Very nice.
800W (theoretical) panels to charge them. Pretty good. November to February (included) maybe not-so-good, but pretty good.
Two smallish inverters. Good to have two for 12V. Intelligently managed, it looks like a pretty good system. For a vehicle especially.

[EDIT] To answer the actual question.. I can't, but personally, I would consider the 200Ah x 12V of the batteries (the core) to be 2.4KWh, and the support system for it to be... adequate. The "utility" system (the inverters), depending on what you (plan to) power with it, very likely so as well.
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