I just talked to a person who had her panels installed on the east side of her house, based on the sunrun person saying the best. Her west facing has nothing.
Am I missing something that east is good?
Am I missing something that east is good?
East facing panels the best?
- Thread starter h2ofun
- Start date
jhn_
Member
Depends on the exact location’s specifics of shading, horizon blocked by mountain or buildings, angle of the roof, etc. But in order of generation potential without those specifics: south, west, east, north. Of course then there are all the directions in between the cardinal directions, SW, SE, ESE, WSW... 
I would disagree with west being better than east, without specifics. From a pure generation standpoint - that is maximizing kWh for the year - I would expect east to be better, because it is typically cooler in the morning. Of course, specifics really do matter - if you tend to have morning fog or afternoon storms, for example, that will have a big effect.Depends on the exact location’s specifics of shading, horizon blocked by mountain or buildings, angle of the roof, etc. But in order of generation potential without those specifics: south, west, east, north. Of course then there are all the directions in between the cardinal directions, SW, SE, ESE, WSW...
However, from a cost and usage perspective, west is often more adventageous. If your usage is higher in the afternoon, then it might be preferred to have west-facing panels to minimize storage losses, to minimize grid interaction, or to minimize costs if you do not have full NEM. Additionally, TOU rates would often make west better as you are producing more during peak periods. (Of course, I would think that having both east and west could often be even better, because you could put more production on the same amount of inverter and have more constant production throughout the day, but I am assuming for now a case where you have only one option.)
All of that said, in our area, where we have full NEM, no TOU rates, and probably tend to lose more production to heat/weather in the afternoon (particularly summer thunderstorms) I would expect east to be better than west if I had to choose one or the other.
Without knowing all the details of this story, I could only speculate, but maybe the installer finds selling customers on the biggest annual production number is the way to go. If they really do have full NEM and no TOU rates, that may be fair. But in places like CA, I think TOU rates and at least some non-bypassable charges are the norm.
holeydonut
Supporting Member
IMO, in NorCal, westward facing should be better (I'm in Contra Costa County). At least around here, there's a somewhat frequent occurrence where the morning has a bit of haze that burns off around 10am. So if you look at my production charts on some days, it's choppy on the left side but smooth on the right side.
If I had to choose between East and West I'd pick West to get more of that smooth curve.
And, technically you want West-facing to maximize the TOU plans. The EV2A shoulder and near-dusk peak encourages making as much energy late into the day as possible. Assuming she doesn't have Powerwalls, she'd rather produce energy later than earlier since every little bit helps.
But what do I know; Sunrun is the nation's largest solar installer and originated here in NorCal. You would assume they have some body of knowledge to suggest East is better?
If I had to choose between East and West I'd pick West to get more of that smooth curve.
And, technically you want West-facing to maximize the TOU plans. The EV2A shoulder and near-dusk peak encourages making as much energy late into the day as possible. Assuming she doesn't have Powerwalls, she'd rather produce energy later than earlier since every little bit helps.
But what do I know; Sunrun is the nation's largest solar installer and originated here in NorCal. You would assume they have some body of knowledge to suggest East is better?
MorrisonHiker
S 100D 2021.4.15
If you could share her address (or one close by), we could look her house up on Google Project Sunroof. Without knowing where her house is located and what obstructions are around, we can't be certain which direction is best for her house.
Our house faces southeast. We have panels facing east, southeast, west and northwest. This helps our system produce throughout the day. While we don't have any trees that could block our system, we have mountains to the east and west which shade our panels for an hour in the morning and an hour at night for about half of the year. The other half of the year, the sun is up high enough that the panels aren't shaded.
BTW, my neighbor just had his solar system installed by Sunrun and his layout looks horrible and definitely won't produce the maximum amount possible. His house is an A-frame (facing east and west) and a wing with due south exposure. They put all of his panels on the east and west facing roofs...the same ones that are shaded half the year because of the mountains. Not only that, but a tree on the west will block out nearly all production from his west facing panels once they leaf out. They put zero panels on his roof that faces due south. So...don't necessarily believe everything someone from Sunrun tells you.
In our house a Southeast and Southwest exposure would be preferable (which we are fortunate to have both), but other things could influence that. Mornings here during winter can be overcast or foggy a lot, with burning off around 10-11am. By noon we tend to have a great bell curve until around sunset. Sun is still high enough in sky to not be affected by our next door neighbor’s 2-story house. Moving out of winter here we mostly have cloudless days and no real weather, just sunny and dry. So by Summer here, mornings or into late evenings should be great for our panel production with our SE/SW panels. Haven’t had them long enough yet to see a full year.
Last edited:
nwdiver
Well-Known Member
I recently completed a 36kW install on a shop with a N-S ridge and a S facing porch. Put ~28kW on the W side, ~8kW on the S side and 0kW on the E side. Peak demand is at ~7pm. West is best.
holeydonut
Supporting Member
Yeah, Sunrun seems to have oddball rules and internal policies that don't make much sense for panel placement. I think it boils down to them relying too much on software, drone/aerial shots, and imposing stiff guidelines on themselves. They don't consider the common sense stuff you may want as a homeowner who lives with the system for decades.
I told Sunrun to MAX out the panels that they could fit on the only roof that was a solar candidate (facing Southeast; I have no useful roof facing Southwest). You'd think this was an open invitation to just go to town adding panels and make money. But that's not actually what Sunrun (or Tesla) would be willing to do.
Instead they came up with some designs that had big-ol' setbacks from the eaves/skylights/chimney that weren't really code-required (I've checked with the County) since the fire-access would come up the Northwest facing roof.
The crew that was doing my PV install showed up, and they went up to take measurements/chalked the panel locations. This was the first time anyone went up on my roof. They told me "this is weird, you could totally fit 3 more panels up here." All the installers and I could do was shrug and pretend like Sunrun's designer knew what they were doing.
Attachments
-
h.JPG
nwdiver
Well-Known Member
Because
It's a better match of supply and demand. It may not matter yet but it will soon.
not only supply and demand, but you are putting more into the grid at higher rates with West vs East
OK. I was trying to understand how production would be different. Looks like production would not be different.
Unfortunately for me, my afternoon production is cut short by 5 or 6 even in the summer by a wall of trees and 500+ feet of hills 1/4 miles west. On the plus side, my A/C usage is not high in the late afternoon so my 2 Powerwalls easily make it through the night. The net is we don't use much power from May-Oct.
MorrisonHiker
S 100D 2021.4.15
For that address, it looks like the east (ESE) facing roof has less shading than the west. The south facing roof would get better sun than the west facing roof but it doesn't look like it could hold many panels. The west facing roof might be a better choice if it wasn't shaded by trees but it is facing WNW, so it probably isn't as optimal as a roof facing due west or WSW.
Wow, had never heard of that tool. Very cool.
This is my house. I love it had my boat lifts and beach.
This shows my south facing garage is great which is where I have loaded up the entire roof. I have some on my west facing which is not as good. I am looking
at putting more on my south facing on house, which again this model says is great!!! Learn something new every day. Thanks
This is my house. I love it had my boat lifts and beach.
This shows my south facing garage is great which is where I have loaded up the entire roof. I have some on my west facing which is not as good. I am looking
at putting more on my south facing on house, which again this model says is great!!! Learn something new every day. Thanks
holeydonut
Supporting Member
Lol imagine how you’ll react if you get a copy of Aurora...
www.aurorasolar.com
Aurora Solar: The World's #1 Solar Design Software
The #1 solar software to design and sell advanced PV systems. See why installers use Aurora to create over 100,000 PV designs every month.
www.aurorasolar.com
That would be cool to have access to that swLol imagine how you’ll react if you get a copy of Aurora...
Aurora Solar: The World's #1 Solar Design Software
The #1 solar software to design and sell advanced PV systems. See why installers use Aurora to create over 100,000 PV designs every month.
As others have mentioned, if on TOU, West is better since you want to generate energy late afternoon. However, if not on TOU and want to generate as much energy as possible, get the exact Azimuth and plug into pvwatts to see which one is higher for your location
pdx_m3s
Active Member
I've noticed here that west is generally better the skies tend to be clearer in the afternoon compared to the morning (no shade either direction).
From a utility standpoint, there really should be higher/better incentives for west-facing panels. That is where the supply is needed most, as peak demand is later in the day.
From a utility standpoint, there really should be higher/better incentives for west-facing panels. That is where the supply is needed most, as peak demand is later in the day.
Similar threads
