Which is better – Solar panels wired in series or parallel?
There is no one-size fits all answer because the wiring pattern used whether series or parallel or both should be selected based upon:
- on the amount of shading that the solar panels are exposed to
- lengths and associated cost of solar panel cables using in the installation
and the available charge controller capacity.
Let us look at how these factors can influence your choice of whether to connect your solar panels in series vs parallel connection or a combination of both series and parallel.
Factor # 1. The amount of shading that the solar panels are exposed to
Are any of your panels likely to be covered by shade ? If so, better to wire the solar panels in parallel. This way your solar panels’ output does not drop considerably when they are shaded.
While this parallel connection handles shading better, thicker (lower gauge) and more expensive cables to handle the higher currents.
If shading is not an issue, you can consider connecting the solar panels in series provided you do not exceed your MPPT controller ‘s input voltage.
Factor # 2. The lengths and associated costs of wiring the solar panels
Solar panels connected in series need thinner (higher gauge) and lower cost wire because the overall current is lower compared to parallel connected solar panels.
Should you have several solar panels exposed to bright sunlight (no shading), you may connect several series wired strings of solar panels in parallel for better system efficiency.
With this arrangement, you can use the more efficient MPPT controllers while keeping the overall current lower compared to purely parallel solar panel connection.
| No. | Series wired solar panels | Parallel wired solar panels |
| 1 | Use higher gauge and lower cost wire because of lower overall solar panel current generated | Use lower gauge and more expensive wire because of higher overall solar panel current |
| 2 | significant power drops when solar panels are shaded (and panels have no bypass diodes ) | Less severe significant power drops when solar panels are shaded |
In summary, parallel connected solar panels handle shading better but need thicker and more expensive solar panel cables than the series connected panels which need thinner less expensive cables.
Should you have many panels, consider connecting several series wired panels in parallel to fully use the capacity of the MPPT controller, handle shading better and without excessively increasing the solar panel current.
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