Should My Boat's Solar Panels be in Series or Parallel?

[@robertduncan4612]

I thoroughly enjoy the quality and balance of your presentations. I do have a request. Can you talk more about the risks and provide examples of incorrect (or poorly maintained) boat/dock wiring can result in electrocution when swimming near available shore power? My guesstimate is that a high percentage of accidental "drownings" are actually "electrocutions".

[@PacificYachtSystems]

Great suggestion!

[@cardinhamkilligrew9712]

Ok, so problem with this... I am planning this now. My idea was two controllers \ two arrays. Each in parallel on a sailboat. I was just told by renogy NOT to do this as it "CAN" over charge the batteries. So, if I have a bimini array and a dodger array, each separate. each in parallel. how do I tie this in to charge the batteries without overcharging?

[@tarivard]

I have a smaller system - 2 x 110W panels with parallel adapters but no blocking diodes. I have breakers on both the input side to controller on positive side and breaker on positive side from controller to battery. For a two panel system, are blocking diodes really necessary? I use a Victron 75/15 controller.

[@Apweng33]

Hi Jeff I have 2 x 100 watt panels running in parallel to a single controller. Tom mentions that one disadvantage of parallel is the need to run 4 wires to the controller(s). I use branch connectors so system is still in parallel and only 2 wires. Does this change anything?

[@PacificYachtSystems]

Hi Andrew, you’d need to make sure the single set of wires from the panels is rated for the current from your 2 x 100w panels in parallel

[@SailingCatamaranElement]

Jeff - If I discover that one of my traditional panels is not outputting power, is there a way I can check the diodes in the junction box to find the issue and are there replacement diodes that I am able to purchase to fix the panel? I am also wondering about diode specifications and what to look for...Victron Energy head office was not able to provide any answers.

[@PacificYachtSystems]

Don't know what an SMH connector is... can you tell me why you want to use want?

[@richardservance8709]

I own a Seattle-based C&C 34+ sailboat. I selected solar panels based largely on size due to limited space to mount them. I have 2 200w Zqcloama panels (42"x11") with an open circuit voltage of 18 vdc. I had originally planned to run each panel to a dedicated Victron MPPT. During testing, it's looking like I need to series connect these panels to get the required charging voltages for my batteries (>12+5=17vdc) in any but the sunniest conditions. In use, my panels will likely face different/partial shading. Both the dedicated MPPT and the series solution seem less than ideal here. I haven't found many small footprint, high output, higher voltage flexible panel options. The off-brand panels seem sturdy and fit nicely in the space I have and minimize cable penetrations and things to mount. Am I thinking this through correctly? What am I missing?

[@PacificYachtSystems]

Be aware, shading is an issue with panels wired in series too.

[@mvdospeces4370]

Interesting thoughts! I have a Victron based system with CERBO. Can the CERBO display the data from five controllers? Another thought... If I have room for 5 panels and a place near them for five controllers why not run a single larger set of cables to a set of buss bars next to the controllers? The wire size becomes larger of course but you only need to run one set of wires. For example my theoretical 5 panel system could use a #2 conductor back to the main DC buss. ???

[@PacificYachtSystems]

Hi MV Lisas Way, your suggestion of aggerating solar controllers unto a single larger conductor back to the battery is definitely an option. For reference, that's how my own 3 solar array at the aft the boat is connected to the house battery. The Victron Cerbo can definitely show multiple solar panels, for instance, i've had 5 solar controllers connected to a Cerbo on my own boat.

[@mvdospeces4370]

@@PacificYachtSystems Thanks! Have you found a reliable solution to aggregate the VE direct cables from the controllers back to the CERBO? It really seems silly to have to run a separate VE Direct cable for each controller. I looked but could not find a Victron Ve Direct concentrator. Thanks!!!

[@richarddukes8720]

I'm currently installing solar panels on my boat. I'm mounting the panels and roughing in the wiring myself. I have a marine electrician set up to do the final connections and fusing. He wants to wire the panels in parallel instead of series. I'm using 4 Sunpower panels - 2 each of 170 and 110 watt and want to use 2 controllers. One for both starboard and port. The specs on the panels say "Max System Voltage" of 45 V. The electrician says that wiring a 170 watt panel and a 110 watt panel in series would exceed that 45 volt maximum. Is he correct or am I misunderstanding something. Wish I was on the west coast so I could have you guys do the installation.

[@PacificYachtSystems]

Hmmm... look at the Victron charge controllers, as they offer a wide range of inputs to accommodate multiple solar panel in series. We've always wired similar solar panels in series (e.g. 170 and 170) and have never mix and match (e.g. 170 and 110) in series. Can anyone comment any issues of putting two different panels in series?

[@richarddukes8720]

@@PacificYachtSystems Sorry, I should have said that I'm using 2 Victron controllers ... the MPPT 100/30 SmartSolar controller. After reading the comment from "Sailing over the Rainbow" below, I believe I'll go ahead with parallel. My panels are on top of my pilothouse and will have very little shading. I really appreciate your videos, they've been a tremendous help for me to understand all of my electrical systems. Not just solar. Wish you were in Florida.

[@youtubeleavemealone]

Misleading title. Very little of this video is about the trade offs between series & parallel. Much more could have been covered on the benefits & disadvantages of each. At a minimum, the title should be adjusted to indicate a discussion of how many controllers to have & the costs/benefits of diodes. By the way, Schottky diodes are commonly used in panels because the forward voltage drop is less than 0.7vdc, but that benefit also comes at a price.

[@embraer1455]

How about microinverters on the panels? or is that what MPPT is? :-) sorry for newbie question

[@PacificYachtSystems]

On boats we use solar controllers (PWM or MPPT) as a way to regulate the power output from the solar panel to exactly what the marine batteries need to recharge and not overcharge.

[@svlotus4379]

Jeff, I truly do enjoy the videos. You have helped us immensely. I am in need of assistance or guidance if you could. I have 4 175w solar panels mounted on a aft Radar Arch and four separate MPPT Vitron controllers. I have yet to route the wires through the Deck/ Hull. Holes are not our friends. You had mention you routed your cables "through". My question is How? Any assistance would be appreciated.

[@PacificYachtSystems]

Recommend using blueseas cable clams for watertight entry into your boat www.bluesea.com/products/1003/CableClam_1.40in

[@barryholiday8998]

Please speak closer to the mic if possible. Thanks for the videos

[@PacificYachtSystems]

Thanks Barry for the pointer.

[@SailingOTR]

"Should My Boat's Solar Panels be in Series or Parallel?" Your video did not address or answer this question. DC power cannot be "transformed" into higher or lower voltages without the use of electronic stepper type transformers. MPPT controllers do not do this. Or am I wrong? Any excess voltage provided by the panels is burned off as heat. Or am I wrong? Many new solar panels provide about 21 open circuit volts. Under load this drops to about 17 volts. To my way of thinking pumping 34 volts into a 12 volt system that requires 13.5~14.2 volts to charge effectively is wasting about 20 volts of available electricity. The excess voltage being burned off as heat. Or am I wrong? Series may be better in low light situations but in good light conditions parallel provides twice(for two panels) the amount of amperage. I recently installed two new 200 watt panels. At first I wired them in series and then checked the output in amperes on my controller. For 400 watts of solar panels I was only getting about 7~10 amperes output to the batteries. When I changed the system to parallel My amperage output doubled. Far more effective for charging the batteries.

[@PacificYachtSystems]

Thanks for your comment, totally agree that in good lighting and temperature conditions parallel can be beneficial over series. When faced with shading issues such as on a sailboat we opt for series so that even if one panel has low light and low voltage another may still provide maximum output.

[@SailingOTR]

@@PacificYachtSystems Fortunately my panels are mounted in the clear. Under certain conditions when sailing they might be shaded but at anchor it's great.

[@denniswoodriff8205]

TOO MUCH MUMBLING. Not clear to hear.