Not sure if I should have tilt on panels heading 262 degrees or not.

[ButchDeal]

The sizes are a little different but mostly the STC difference. You would need more lg315 modules to get the same performance as the Panasonic 325 modules

[DaveDE2]

Tilting them would just add more shadows and cut down on the number you could fit there.
I would do something like this which fits 65 modules, 20.8kw. I used LG320 modules with SolarEdge SE11400 inverters.
Should produce about 21.6MWh first year.

@rsilvers
Beautiful home!

@Butchdeal
So you can generate a model like that just from a google earth photo and gps coords?! Awesome.

[rsilvers]

Thank you.

In the end, I will probably do what ButchDeal came up with, except without the three East panels.

[ButchDeal]

@Butchdeal
So you can generate a model like that just from a google earth photo and gps coords?! Awesome.

We use google earth, LiDAR, street view when available, and homeowner photos some times.
We also have preliminary online estimates of costs and productions in many areas based on LiDAR all precalculated and instant online info.
We send proposals remote, customers sign, we send a local installer to review things, check measurements, and electrical issues.
An addendum is sent based on any changes, and there you go install starts.

Our entire national business model is based on this.

[huge]

Butch, can you please provide us with the name of your company? I know you can't post a link to it, but maybe we can search online for it.

[DaveDE2]

Thanks Butch, looks like you're all over it. Where does LiDAR info come from?

[ButchDeal]

Thanks Butch, looks like you're all over it. Where does LiDAR info come from?

The government, local, state, and federal. We have collected one of the largest private collections of LiDAR

[DaveDE2]

The government, local, state, and federal. We have collected one of the largest private collections of LiDAR

Very cool. I've been on the inside of it for so long that I haven't looked outward for what it has done insofar as what has (finally) come to market. I've been doing LiDAR design and development for the past 20 years or so with a few of the top companies in the field, deep in the trenches of refining what it takes to get to market what's affordable for given markets. My endevour has been mostly military stuff that is higher performance and yet to be available for commercial.

Thanks for sharing.

[rsilvers]

Today is roof measurement day. They are coming over with a SunEye 210 to check shading on every roof facet.

[rsilvers]

They are up-charging me 3 cents per watt more to go from LG315 to LG320.

One could argue that more dollars per watt is never worth it, but I am going to do it, since I want a larger system and am limited by roof space. Plus I will get more SREC2, and I will just feel better about having the latest.

[solarix]

Due west (or east) panels are not that bad. Maybe a 10% loss from due south. Fixed PV panels produce most all of their power during a 6 hour window so 11am to 5pm is not much worse than 9am to 3pm. Use PVwatts to compare and you'll see. Tilting panels used to be more common back when they were four times as expensive. Now, put 'em flush so they will look good and can fit more in.
315w panels are 6.5ft long vs 5.5ft long for the more common, lower priced ~260w panels. The actual dimensions of your roof will dictate which size is a better fit. They are both the same watts per sq ft though.

[sensij]

The LG 315 are 60 cell, about the same size as the conventional 250-280 W panels. The larger 315's described by Solarix are 72 cell like those made by Solarworld or Canadian Solar.

[rsilvers]

Due west (or east) panels are not that bad. Maybe a 10% loss from due south.

Depends on location and tilt, but in MA with a 40 degree tilt, it is a 25% loss. With a 20 degree tilt, more like 15%.

[J.P.M.]

Tilting panels used to be more common back when they were four times as expensive. Now, put 'em flush so they will look good and can fit more in.
315w panels are 6.5ft long vs 5.5ft long for the more common, lower priced ~260w panels. The actual dimensions of your roof will dictate which size is a better fit. They are both the same watts per sq ft though.

I'd comment that the farther an installation is from the equator, the more beneficial higher tilt angles become and may be necessary if a system is expected to make cost effective production and/or reasonable winter production. Not everyone lives at 35 deg. or less latitude or has a high clearness index in the winter. Tilting panels is more work/expense, but may be necessary depending on application. Also, as you know, higher tilts have greater off south production penalties. New England is not the world's best solar climate. Flagstaff is pretty close to ideal.

[rsilvers]

Looks like I am ending up with 73 panels - 23.36 kW. I was hoping for 25kW, but oh well.

[NYHeel]

Wow, that's one large residential system. How much energy to you typically use in a year?