Question Solar panel selection

[Rich-MLsRV]

Folks,

I am considering using AMsolar solar panels. I like the AMsolar panels since they use VHB tape for mounting and hence don't need to drill into the roof. Folks that have used the VHG tape method for mounting have not had a issue w/ the panels detaching. I am planning to have 6 solar panels configured 3 parallel sets of 2 series panels.

I think in selecting a panel one needs to consider the voltage drop from the roof to the batteries and the solar charge controller base on voltage and current into the solar charge controller.

For the GS200 (price $299/panel including mounting hardware and wiring) I came up with
Voltage drop: 0.58
Voltage drop percentage: 1.44%
Voltage at the end: 40.04

For the ZS190DJ (price $525 / panel including mounting hardware and wiring) I came up with
Voltage drop: 0.28
Voltage drop percentage: 0.34%
Voltage at the end: 81.52

My thinking is it's hard to justify the more expensive ZS190DJ when looking at the voltage drop from the roof to the solar charge controller / batteries in the basement. The ZS190DJ, because of the higher voltage / lower current into the charge controller, would need a cheaper solar charge controller. Victron MPPT 150/85 for the ZS190DJ and Victron MPPT 250/100 for the GS200.

Are there other considerations I should be taking into account in selecting the solar panel?

Thanks

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Details are below in case you wanted to view my calculations

The panels I am considering have the following specs.

GS200

and ZS190DJ series configuration

I calculated the voltage drop from the roof for each of the panels

GS200 with the series / parallel I mentioned above

For the ZS190DJ

 

[Neal]

Grape Solar panels are good, @Chuggs got his from Home Depot. You can buy the mounts separately from AMSolar and install yourself on any panel. You can also ask AMSolar for discounted panels, can't remember what they call them but they have a stock of panels they can't sell as new as they may have a scratch, and you can get them deeply discounted. I got my last two from them that way as they didn't have stock on new and it ended up working out great. You may not even see the defect and the scratch doesn't affect anything other than their ability to sell it as new.

The original panels I bought from AMSolar were not Grape Solar, the two I bought later to bring me from 8 to 10 panels were Grape Solar and I think they had better specs, which all of mine were Grape Solar.

 

[Rich-MLsRV]

@Neal - Thanks for your response.

Did you place the panels along side the A/C units? Have you encountered much shading on the panels during the day? I would think not but wanted to check whether you you took precautions to prevent shading on the panels.

 

[Neal]

I wish I was as good as @Chuggs with picture keeping as I can't find a pic of my roof as of yet. If you get shading from an AC then the sun angle is so low you won't get anything decent for solar energy. The biggest issue with shading is if you tilt panels and one blanks another, I had that with mine at Quartzsite but I also learned that during the winter with low sun angle solar is a challenge even with 10 panels tilted directly into the sun. I'm no longer a fan of tilting them, the two times I did it was futile. We'll see, Quartzsite in January wasn't much else you can do.

Make sure your panel layout allows you to walk your roof. It is a required part of the planning.

 

[AbdRahim]

How do you guys walk on the roof with all of those panels?

 

[Neal]

How do you guys walk on the roof with all of those panels?

Gaps between them.

 

[AbdRahim]

Sounds acrobatic.

 

[Neal]

Sounds acrobatic.

 

[Soniccruzer]

Here is my set up

 

[Neal]

Awesome! Gonna need some of that next time around!