Originally Posted by hotfishtacos
...It is important to use panels with the same output voltage (about 17 volts). Then the panel watt values can be mixed. The 160 I have is the highest watt panel I could find that is low voltage. Panels used on houses are much higher voltage. Mine are all around 17 volt. ...
Mixing the high voltage (34-36v) panels with the low voltage (17-18v) panels does no harm except
to your pocketbook - IF
- there is a blocking diode in each panel before the common connection. ( And there really should be.) The lower voltage panels will not contribute wattage until the drain on the solar system exceeds the wattage of the higher voltage panel.
The impact to the pocket book is that you paid for high voltage and then lost that power in the regulator when it drops it down to 13.7v for charging the battery. The difference in 34 to 13.7 is converted to waste heat. Plus, the higher voltage panels tend to be twice as expensive, so you have lost $ in two ways.
There is a partial exception to this rule-of-thumb. If you spend the big $$$ on a MPPT regulator then you will get all the power the big panel will produce. (A good MPPT regulator can run $400 and up.)
Now, if someone gives you a house-style panel for free, then go for it, but monitor the regulator for excessive heating.
Bottom line: Mixing low and high voltage panels could work but it gets expensive and complicated. Escape trailers are happier with 17-18v panels.