Solar on the shady side of the roof

[RichardCullip]

Interesting that the metric is % of a monthly bill. I would rather see the yearly kWh produced for both scenarios. You can run your own solar production estimate using the pvwatts tool found on-line. Just make two runs, one for the sunny side and one for the shady side of your roof. This should give you an unbiased estimate of your solar production which you can compare to your total demand.

[dreamypenguin]

So, I'm having one of those moments where I don't know what's true between two installers. Maybe wise forumdwellers can help.

Got two sales pitches for Roof + Solar, one from Semper Solaris and one from Simmitri, both reputable companies. My sticking point is one bid had panels on both sides of the roof, one didn't. I use a lot of kWh every month, and here's what they both said:

Simmitri: you can totally put another $10k of panels on the shady side of the roof. They will each produce about 3-4% of your total bill every month, unlike the bright side where they'll produce about 7%.

Semper: it's not worth it to put panels on the shady side of your roof. (doesn't even offer it as an option). Also comments that to put them on the shady side, they would need to install a "tilt kit" and it increases risk of roof leaks, so no bueno.

I have no problem with less-efficient solar panels if they are still significant - e.g. if they pay for themselves in 7 years instead of 4. I can't tell what the subtext is here. Should installers avoid tilt kits because they really do compromise roofs? I was kind of surprised they were concerned about that since I'm buying a brand new roof - seems like they could ensure the whole thing happens properly. Simmitri says they have like a 25 year warranty with no deductible on any repair including leaks.

Is there some risk that because Simmitri hasn't been out to see the house in person (Semper did come out in person) that they might just be wrong and panels on the shady side will be really bad, like 0-1% of my bill instead of 3-4%?