There are obviously pros and cons to different combinations of size and number of panel when dealing with a limited size space. As an example, If one is planning to install 600w of solar on an RV roof is it better to use 6- 100w panels or say 2-300w panels. One charge controller or two?
Designing and sizing a limited mobile system
- Thread starter 1holaguy
- Start date
The answer is it depends on your situation. The shape of your roof your budget and a bunch of other variables. No one size works best for all setups.
I guess I was wondering if there is a difference in performance. Example : If you have 6 100w units and two are partly shaded you still get out put from the 4 in full sun. If you have two 300w panels and shade on one you only get out put from 1 unit. So in this comparison you might see 400w out put vs 300w output. DO i have this correct?
Rogerb
Knows just enough to be dangerous to himself
Kind of.... If all 6 100w panels are paralleled to the charge controller, yes, any of the 6 could be shaded, and the others will still produce. Same with the 300w panels, in parallel, one could be shaded, the other will still produce. That said, if you serial all 6 100w panels, or both 300w panels, then shading any will impact the string.
You also must take into consideration the type of solar charge controller you use and it's limits.
You also must take into consideration the type of solar charge controller you use and it's limits.
Tomthumb62
Solar Wizard
- Joined
- Sep 25, 2022
- Messages
- 1,871
More panels of lower wattage means more wiring and MC4 connections. MC4 connections can fail, as can any connection. Some people clip off the MC4 connectors and make direct splices with marine grade heat shrink for weather proofing.
Fewer panels of higher wattage mean less wiring and connections.
Also, with 6 x 100W panels you can get more creative in wiring them together, such as 2s3p or 3s2p or 6s or 6p, depending upon your charge controller and expected shading issues (if any). Remember that any configuration of 3P or more needs to have every panel individually fused or use a combiner box with integrated fusing.
With 2 x 300W you’re limited to 2s or 2P, depending upon your charge controller and shading issues.
With more panels, if one fails, you have the others to still function. Especially with 6p. With only two panels, if one fails, then your production will be halved.
Fewer panels of higher wattage mean less wiring and connections.
Also, with 6 x 100W panels you can get more creative in wiring them together, such as 2s3p or 3s2p or 6s or 6p, depending upon your charge controller and expected shading issues (if any). Remember that any configuration of 3P or more needs to have every panel individually fused or use a combiner box with integrated fusing.
With 2 x 300W you’re limited to 2s or 2P, depending upon your charge controller and shading issues.
With more panels, if one fails, you have the others to still function. Especially with 6p. With only two panels, if one fails, then your production will be halved.
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