Question for you pros out there…
I’m doing a van build and it is solar time! I recently purchased the Bluetti EB240.
Now I am trying to figure out the solar panel situation. I am considering the following panels. I have a bit of a space issue so in order for me to maximize watts with the space I have I’ll need to get one 200w panel and two 100w panels to fit on my roof and around the roof top vent.
Is it recommended that I wire everything in series together?
Or is it not recommended to wire different wattage panels in series?
What is the work around for this?
BougeRV 9BB Cell 200 W
Open Circuit Voltage Voc (V) 21.62±3% V
Max Power Current Imp (A) 11.12±3% A
and
BougeRV 9BB 100 W
Open Circuit Voltage Voc (V) 21.4±3% V
Max Power Current Imp (A) 5.51±3% A
@ibline Since the internal circuitry of solar panels of different sizes is inconsistent, we recommend connecting solar panels of the same model in series.
The solar input VOC of the EB240 is 16-68V. 500W Max.
It is suggested you connect two 200W panels in series.
Normally the rule is to wire panels with the same voltages, in parallel. The current of each string will add together.
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If you have different wattage panels, but with the same ampere (current) level, choose a series connection. This will increase the voltage of the system.
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If you connect two modules with different current levels, the output will be based on the current of the lower module, leading to power loss.
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What you can do it try it both ways and let the app show you which is giving you the most power output. Lay out the panels on the ground and try different configurations, preferably during a cloudless blue sky day. Throw blankets (or cardboard) over them while plugging/unplugging them and double check the wiring before removing the blanket. Take screenshots/pics so you can keep track of everything.
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Just some quick math, since the voltage is almost the same, should you wire all three in parallel, you will have 22.14 Amps at 21.4 Volts = 473 Watts. (Note, use the Vmp for calculations, not Voc. So it will likely = 400 Watts, give or take a few watts.)
If you wired them all in series, 21.4V+21.4V+21.6V = 64.4V. The current will be that of the LOWEST panel, 5.51A.
So 64.4V x 5.51A = 69.1 Watts
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Again, for SERIES, the panel with the LOWEST current will drag down the other panels to that current level.
(For PARALLEL, the panel with the LOWEST voltage will drag down the other panels to that voltage level.)
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Lastly, you could wire the two 100 watt panels in parallel, THEN wire that in series to the 200 watt panel. That will give you higher voltage at lower current, which is preferable, (can use thinner wiring). Power output will be the same, approx 400 watts.
Make sure all wiring is protected with fuses (or DC circuit breakers). Inline fuses are quick and easy, just plug them in. (Fuses protect the wiring, not the equipment. Some misunderstand that.)
