Hello from Sacramento, calif area

SolarHelper

New Member
Joined
Aug 23, 2021
Messages
4
Hi,
just want to say hello to everyone and really appreciate having a site to kick around solar projects and such. Would like to hear comments about using the PVWatts website for system sizing and Google Sunroof for panel placement.

My neighbor wants to add a Grid-Tie solar system to his house roof and using the PVwatts website and the Google Sunroof estimates a system between 8.6kw and 9.3 kw would work for his 12,200 kwh annual load. Bids from multiple companies spec the system size should be between 11.2kw and 15.1 kw however and panel placement is different for each company.

Thanks for your thoughts.
 

A.Justice

Swears he didn't start that fire.
Joined
Sep 12, 2020
Messages
828
Location
TN
I won't go into the math for your specific situation because there are so many variables involved. A local installer would probably know more about local sun conditions.

However, I will say that the panels are normally the cheapest part of the system, and over paneling is never a bad idea if you have the space. Better to have too much, than not enough.
 

SolarHelper

New Member
Joined
Aug 23, 2021
Messages
4
Thanks A.Justice for the comment. I’m not really looking for specifics other than are there others here who have used Google Sunroof as a guide to panel placement and how did it turn out. I used it on my own 6.8KW system with 20 panels and get 100% bill coverage. Whereas a bid from Solar City at the time specified 24 panels and claimed only 84% bill coverage. Panel placement was noticeable different than what I used.
 

Supervstech

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Sep 21, 2019
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6,536
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Belmont, NC
It seems like a decent sales tool to push solar bids. It certainly doesn’t accurately calculate irradiance… too many variables.
 

LazyAcres

New Member
Joined
Aug 29, 2021
Messages
4
One thing to note is that during fire season you will get less from your panels. The smoke/haze reduces the panel output.
 
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