East Array + South Array + West Array ?

[bcroe]

Probably a dumb question but if you use a bigger inverter than it could capture all of that solar energy without clipping so why not have them all facing the sun at the same time? there is a new 7000w sma 22 inverter on ebay for $1050, but the seller told me he would take $800 so relatively inexpensive IMHO. Having arrays at 3 different orientation also seems to take up more useable land and doesn't look as neat or nice as a single long row of panels.

In a dream world you can constant keep changing factors to overcome some limitation
or other, but only to create a new one. In the real world everything has practical limitations,
and an arrangement you can live with (despite limitations) must be chosen. Using a bigger
inverter was not an option for my situation, your results may vary. Bruce Roe

[Ampster]

That is a little under $2 a Watt. What TOU plan did you go with? Are you happy with it?

[Billybob9]

This is a house in San Diego Ca. Originally was going to have an installer do it but we just weren't on the same page and he was an Enphase installer. There are enough SMA videos that if you know Basic Solar and ohms law you can figure it out. I was wrong on the cost it was only 9K and if he would have done the job it would have been 12K.

[Ampster]

Self installed on a roof? What is the location?

[Billybob9]

I just Installed a SMA 5.0 inverter with 16 Canadian solar panel ( 60 cell ) 300W on 2 strings because there were no shading issues . Rapid Shutdown, Rails wire and hardware. All for about 12K.

[Markyrocks69]

Yes, the wires are already over-sized for the 21 amps, from the 5 KW Inverter, to keep the % Voltage Drop low.
The wires would need to be even larger the for 32 amps from the larger 7.7 KW Inverter.
An increase of 10 amps, from a 30 amp Breaker to a 40 amp Circuit Breaker is a huge difference because ...
you cannot add a 40 amp breaker, for a 7.7 kw Inverter, into a typical 150 Amp Panel, without derating the Main Circuit Breaker.

No, it is not about the pennies - it is about the dollars.
The goal is not about spending the most dollars ...
The goal for us is to spend the LEAST dollars, then design for the highest "kWhrs per Year" of AC Production to yield a very short break-even time frame.
The big picture is about decreasing the break-even time frame, we do not spend any dollars unnecessarily.

You are correct about the point of the breaker size ect but I highly doubt that you not having spent money unnecessarily. Like I said money spent now could save alot more in the future if you and your "friend" ever decide to upgrade the system.

Buying 275 watt panels instead of like 340s means you had to buy more hardware, more rails. Unnecessary. You probably could have bought 340s and bought 10 less panels. Even tho the bigger panels are more expensive. Would still be less per watt overall. I doubt your using aluminum wire and a roof install is always cheaper than ground. I don't buy what you're saying about spending unnecessary dollars to maximize roi ect. Bc it sounds like alot of unnecessary spending. How much is this 5kw system projected to cost all in?

[NEOH]

Majority of these items would allow future expansion for pennies compared to the big picture. I'd personally want to oversize the wires anyways. Really not much money difference between 30-40amp breakers.... why would you need a bigger panel in the barn over 10 amps? If you only have a 100 amp panel in there that's basically full your probably screwed without a tap either way....

Yes, the wires are already over-sized for the 21 amps, from the 5 KW Inverter, to keep the % Voltage Drop low.
The wires would need to be even larger the for 32 amps from the larger 7.7 KW Inverter.
An increase of 10 amps, from a 30 amp Breaker to a 40 amp Circuit Breaker is a huge difference because ...
you cannot add a 40 amp breaker, for a 7.7 kw Inverter, into a typical 150 Amp Panel, without derating the Main Circuit Breaker.

No, it is not about the pennies - it is about the dollars.
The goal is not about spending the most dollars ...
The goal for us is to spend the LEAST dollars, then design for the highest "kWhrs per Year" of AC Production to yield a very short break-even time frame.
The big picture is about decreasing the break-even time frame, we do not spend any dollars unnecessarily.

[Ampster]

sorry must of missed that, ........

Yes, it is worth a couple of rereads. There are some unique system approaches based on location, weather and personal philosophy about being Net Zero.

[khanh dam]

sorry must of missed that, only thing I read was bigger wires to carry more amps, which doesn't make sense to me. one wants the most power, so more amps is good and copper wire going from 10 to 8 or whatever isn't really that big of a cost. Probably just as expensive to buy the extra cement for footings for 3 separate arrays vs one big one.

[Ampster]

Probably a dumb question but if you use a bigger inverter than it could capture all of that solar energy without clipping so why not have them all facing the sun at the same time? ...

The answer is explained earlier in the thread.

[khanh dam]

....... So I do not want them to all be facing
the sun at the same time. Bruce Roe

Probably a dumb question but if you use a bigger inverter than it could capture all of that solar energy without clipping so why not have them all facing the sun at the same time? there is a new 7000w sma 22 inverter on ebay for $1050, but the seller told me he would take $800 so relatively inexpensive IMHO. Having arrays at 3 different orientation also seems to take up more useable land and doesn't look as neat or nice as a single long row of panels.

[NEOH]

Here's something to consider. Facing west you will get the most out of your array when the sun is going down. If your utility company is charging you more for hour from 4-9 ( like mine is ) West is Best to keep alive as long as possible. SMA was nice to make all 3 channels independent so shading and other factors like this could be done.

In message #25, I had posted ...

"...
Electric company does offer a Residential (TOU) Time-of-Use plan = Off Peak starts 8:00pm until 8:00am M-F & all weekend
I do not know of anybody that has switched to that plan.
..."


So, I got to talking with my neighbors about our Solar Panels and Time-of-Use plans.
Someone had this idea ...
Wouldn't the above Time-of-Use plan be better for the neighbors that have Solar Panels?

His theory was ...
On the T.O.U. plan, you pay MORE per kWhr from 8:00am - 8:00pm (day time) but you offset ( all / most ) of your usage with Solar Panels from 8:00am - 8:00pm
On the T.O.U. plan, you pay LESS per kWhr from 8:00pm - 8:00am (night time) when our Solar Panels are dark.

If the Solar Array can offset the expensive Grid kWhr's during the day ( to near 0 kWhrs ) then we mostly consume very cheap Grid kWhr's at night?
We need to verify that the T.O.U. Plan is available to homes with Net Metered Solar Panels.
I think, both the electric hot water tank and the clothes dryer are 5,000 Watts - so, we shift big loads to 8:00pm - 8:00am and weekends, only.

[Billybob9]

Here's something to consider. Facing west you will get the most out of your array when the sun is going down. If your utility company is charging you more for hour from 4-9 ( like mine is ) West is Best to keep alive as long as possible. SMA was nice to make all 3 channels independent so shading and other factors like this could be done.

[bcroe]

The 7.7 kW inverter costs more than a 5 kW inverter and the bigger Inverter generates more amps ...

More amps = bigger wire = more $'s
More amps = bigger Circuit Breakers = more $'s
More amps = bigger AC Disconnect = more $'s
Bigger wire = bigger conduit = more $'s
More amps = bigger electrical panel in his barn = more $'s ( cannot de-rate Main CB )
Bigger panel in barn = bigger underground wire to the barn = more $'s

The 7.7 kW Inverter only increases yearly kWhr production by 4% - 5%.

All three (3) PV Arrays, of 10 panels each, pointing due South appears to be the BEST Layout for maximum Yearly kWhr production

I maximized the "Yearly kWhr Production" value, what parameter do you maximize to select "South-East + South + South-West" as better?
Is it based on a Time-of-Use plan = changing price of electricity ?

Use what works best for you. There are a few reasons that is different from what is
best for me. One is, my DC:AC ratio is much higher than yours, to make power under
clouds. Another is, many days here I have seen a clear sky at -20F causing panels
facing the sun to produce close to their rating. So I do not want them to all be facing
the sun at the same time. Bruce Roe

[nwdiver]

I maximized the "Yearly kWhr Production" value, what parameter do you maximize to select "South-East + South + South-West" as better?
Is it based on a Time-of-Use plan = changing price of electricity ?

I had a ground mount in the spring that was somewhat similar but larger. We were limited to ~15kW due to export constraints so we installed 22.77kW on (2) 7.7kW SMA inverters. 11 345w panels per channel. One aspect I didn't fully consider is that facing the array west or east decreases the angle south => acts to increase summer generation at the cost of winter generation. However there's a ~27kW system I also helped with next door and the 22.77kW system is producing more energy at 5pm than the 27kW due to the West facing panels.

If you expect net metering to be around for awhile then 100% South. If you want to increase self-consumption then maybe angle a couple slightly west.

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