Please help me understand my production rate vs my system size.....???? Confused...

[J.P.M.]

Yes, i've seen the graph, and that makes great sense. thanks.
But in an 'ideal world', is what i'm stating below accurate?

305Watt is the maximum amount of power that can be produced by one panel in an hour under ideal conditions. 33 x 305Watts equals ~10,000 Watts (ie. 10kW) of energy that can be produced under ideal conditions in an hour.

The operative word here is "ideal". The short and practical answer is usually something like this: Output of a 305 W panel will not be 305 W/panel under most conditions.

Reason: You are confusing "ideal" conditions - which do not exist by definition - with something called "Standard Test Conditions" = S.T.C. (which do exist by definition).

A new and clean panel's output is measured under controlled conditions with an irradiance source similar but not identical to the solar spectrum of 1,000 W/m^2 radiant energy flux in the plane of the array (P.O.A), no wind and with a cell temp. of 25 C.

Most or all actual operating conditions will be different from that test condition. Usually, but not always, under clear skies and normal (perpendicular) irradiance and little wind, cell temps. will be the biggest factor that in lower than S.T.C. output, with cell temps. probably ~~ 25-30 C. above ambient and each deg. of cell temp. above 25 C. decreasing panel efficiency by something like ~ 0.5 %/deg. C. or so.

Those cell temps. are influenced mostly by :
1). Irradiance level (more P.O.A. irradiance increases cell temp. just like a black surface sitting in the sun gets warmer).
2.) Wind (more wind decreases cell temp. just like when you blow on your food to cool it off).
3.) Dirt/fouling on the array. More of a variable and perhaps, but not always of a minor nature, but in a somewhat more complicated way (more dirt generally decreases irradiance on the array with that irradiance decrease lowering output, but also decreasing call temps., with those temp. decreases tending to increase cell efficiency and thus increase output. The net result of all that usually being a decrease in output).

It is also possible, and probably likely, that during some times, like around this time of year, on cold, windy and clear days, conditions may temporarily exist that will allow an array to exceed S.T.C. output. Those conditions won't last long at elevations close to sea level in warmer climates.

Output in excess of S.T.C. output can also regularly exist at higher elevations where P.O.A irradiance levels can and do regularly exceed 1,000 W/m^2 and with amb. temp. relatively low, array orientations favorable and the wind is kicking ass. add to that ground snow cover albedo adding further P.O.A. irradiance increases. Think of places like Santa Fe, NM or in the Rockies with south facing arrays at 60 deg. tilts.

[bcroe]

Those of us with some shade expect the edges to be clipped off that nice, south-facing-panels curve, till
the sun rises high enough to clear the obstacles. Bruce Roe

[ButchDeal]

Yes, i've seen the graph, and that makes great sense. thanks.
But in an 'ideal world', is what i'm stating below accurate?

305Watt is the maximum amount of power that can be produced by one panel in an hour under ideal conditions. 33 x 305Watts equals ~10,000 Watts (ie. 10kW) of energy that can be produced under ideal conditions in an hour.

305wh not watts and NO it can actually produce more than that if it is very cold out, but you should not expect it to produce that particularly on warm days.

NOTE it is a 305watt PV module capable of spitting out 305watts at STC and in an hour would generate 305wh (see where the h goes)
it is like this 305w X 1h = 305wh

[Sunking]

No you are confusing energy and power.

Power = Watts, the rate at which energy is being consumed.
Energy = Watt Hours = Watts x Hours.

Example lets say you have a 100 watt light bulb and you run it for 10 hours. 100 Watts x 10 Hours = 1000 Watt Hours. The light uses 100 watt and if used for 10 hours consumes 1000 watt hours (1 Kwh) of energy.

So your system is calculated to generate 12,000 Kwh/year. So your system on average generates 12,000 Kwh / 365 day = 32.8 Kwh per day. That means you have roughly 32.8 Kwh / 10 Kw = 3.28 Sun HOURS per day on average. So you are looking at the wrong numbers. You want to know how much energy (watt hours) you generate in a day, not how much power (watts) the system generates at a given moment in time.

It is like saying you are asking that you have a 250 hp engine in your car. How far can I go and how long will it take me to get there? Complete nonsense right?

So the answer to your question is your panels will never generate 10 Kw. At best around 8 Kw and if they generate 8 Kw x 1 Hours = 8 Kwh. You need to get your head wrapped around the difference between Power (watts) and Energy (Kwh). They are not the same thing.

[SunEagle]

Real life will never be "ideal" so you should expect a lower than 100% of the nameplate wattage as output for any pv panel.

The Imp value is the highest amount of amps the panel can produce based on an Irradiance of about 1000w/square meter. There is also a factor due to temperature of the cells.

Both of those variables are taken into consideration in the "lab" while the panel is being tested. You will never see "lab test" conditions in the field so the panel will never put out 100%.

[sharpd1]

No mystery at all. Panels do not generate their rated capacity. Panel specified capacity is under ideal test conditions in a laboratory. Real world is roughly 80 to 90% for a few minutes around solar noon. If you watch from sunrise to sunset, at first light you may only produce a few hundred watts. As th esun gets higher in the sky, power increases gradually until you hit solar noon which will be peak power of 80 to 90% of the spec. Then a few minutes afternoon power gradually decreases until sunset. If you plot power vs time you will have a Bell Curve. Something like this 3 Kw system in summer.

Yes, i've seen the graph, and that makes great sense. thanks.
But in an 'ideal world', is what i'm stating below accurate?

305Watt is the maximum amount of power that can be produced by one panel in an hour under ideal conditions. 33 x 305Watts equals ~10,000 Watts (ie. 10kW) of energy that can be produced under ideal conditions in an hour.

[Sunking]

No mystery at all. Panels do not generate their rated capacity. Panel specified capacity is under ideal test conditions in a laboratory called STL. Only in space will a panel produce full power. Real world is roughly 80 to 90% for a few minutes around solar noon. If you watch from sunrise to sunset, at first light you may only produce a few hundred watts. As the sun gets higher in the sky, power increases gradually until you hit solar noon which will be peak power of 80 to 90% of the spec. Then a few minutes afternoon power gradually decreases until sunset. If you plot power vs time you will have a Bell Curve. Something like this 3 Kw system in summer. Note solar noon occurs at roughly 1:30 pm. You must be one big energy hog to use 33 Kwh/day like me. National average is just less than 10 Kwh/day

[sharpd1]

Hi,
so, the good news is that i recently took the leap and bought a 10.06 kW system (capable of generating 12,000 kwh annually). I have 33 individual 305watt panels. I have a solaredge inverter.
As i monitor the power generation, i've notice that my MAX production on a sunny warmish day is 8kW. it sometimes dips to 7.4, 7.5, 7.9, but never 8.1 or above....which leads me to believe that it's capped at 8.0.

So, here's my confusion: 33 x 305W gives me ~10kW. My MAX generation rate is showing at 8kW on the App. I'm trying to understand what there's a difference.....should it say 10kW on the App when it's nice and sunny?

Sorry for my noob-ness but i thought someone here might be able to explain in a way that i'd understand.

thanks in advance!