Need help with series or parallel

Technically--the utility looks like a "voltage source" (or an "AC Battery"--Which keeps the 230 VAC voltage "stable" regardless of load).

A typical Grid Tied Inverter looks like a "current course" (or constant current device--current level based on the amount of sun hitting the panels at any point in time).

As far as your "billing" is concerned, yes, the solar panels+GT Inverter will "spin the power meter backwards" when loads are less than GT inverter output--And "recharge" the utility Grid.

Unless you have electrical or electronics experience--"Normal" people rarely experience a "current source" and how it functions.

https://en.wikipedia.org/wiki/Current_source
https://en.wikipedia.org/wiki/Voltage_source

We can discuss it more if you are interested--Current sources are actually quite interesting devices and are very heavily used in integrated circuits (typically analog devices). Arc Welders and Florescent Ballasts are also examples of current sources.

As far as your A/C systems, lights, etc... their starting surge and the 230 VAC line voltage is "stabilized" by the utility itself (also know as a voltage source/sink). Having a "current source" recharge a "voltage source" is very common and work well together.

I am not sure how far you want to take this discussion (your choice--just ask).

-Bill "I type too much sometimes" B.

Watts is a "rate"--Like Liters per minute

Watt*Hours is an "amount'--Like total Liters pumped

So, if you have an "average load" of 62250 Watt and run it 10 hours per day:

• 62,250 Watts * 10 Hours per day = 622,500 Watt*Hours = 622.5 kWH per day

But you will not have "full sun" 10 hours per day--So you need a larger array that can output more power (watts) in a shorter amount of time so that the WH used ~ WH generated.

The typical number we use is 77% of solar panel name plate roughly equals the average GT inverter output on a typical warm day (in cold winter weather, below freezing, the solar panel Vmp rises, and P=V*I -- So rising V gives more power with cold solar panels).

• 622,500 WH per day * 1/0.77 GT system efficiency * 1/6.92 hours of sun for peak AC month = 116,827 Watt solar array

Note, in my earlier post above, I made an assumption that your AC units were running 50% duty cycle (motor on for 10 minutes, off for 10 minutes, as an example). Here I just took your number as the average load--So the solar array is much larger based on this assumption.

in the end, you need to understand your power needs pretty closely. And how that may change over the seasons (no AC in winter?).

Also power company billing will have a large effect on your eventual final design.

-Bill

Yes, your # of solar panel math is correct (based on my guesses/examples).

Power Factor is a large discussion in itself--You need to size the branch circuits and main panel+utility on Power Factor for two reasons.

First reason is that the wiring/fuses/transformers (more or less) use VA (Volt*Amps) for sizing the circuits. For example if you have a typical induction motor with poor PF~0.7, then a 4,000 Watt load would look like (made up numbers for example):

• 4,000 Watts / 230 VAC = 17.4 Amps (based on Watts)
  
• 17.4 amps / 0.70 PF = 25.6 Amps (actual wire current based on poor PF)
• 230 Volts * 25.6 Amps = 5,888 VA

Second--The utility itself has to size its wiring/transformers for the VA of your loads, not Watts. So if you have very bad PF, they may apply the 1/0.70 to your billing and charge you more money because of the poor PF.

Then there is the other side of the discussion... First, most GT Inverters output near 1.0 PF -- And some newer models can actually be programmed to output +/- 0.8 PF or so--To offset power PF loads to a certain extent.

Second, for motors, it is possible to add (special) capacitors to the motor (or the utility can do it on their network) to bring the PF closer to 0.95 or so (correct bad PF locally, and not have the bad PF run all the way back to the generator/power station). In California, summer means lots of A/C and water pumping (irrigation of crops)--So the power company will switch in capacitor banks during summer.

Third--There are A/C systems that are designed to have 0.95 or better power factor--So it reduces your problems. Choosing efficient/modern hardware is getting much easier these days. And, it is generally better (cost less overall) to start by looking for very efficient electrical appliances. The new stuff can be much better than what was available 20 years ago. Add insulation to walls and ceilings, double or triple pane widows, etc. are all (usually) worth the time and money--Instead of being tied to high electric bills for years/decades in the future.

Note--This is a basic PF discussion--Poor PF has other causes and effects that can cause more headaches and complexities... Motors+Capacitors are "simple" solution that (usually) do not apply to many other types of loads (computer power supplies, CFL and LED fixtures, etc.). These other "issues" may or may not apply to you (depends on your specific loads and how many of each you have--I.e., if you have a large computer center to go with your A/C system, there are "Power Factor Corrected" type computer power supplies available).

-Bill