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Case study: Pedal powered or solar powered?

We wanted to share with you a case study for a customer with a pretty unique marine application! East Coast BrewBoat is a super fun, 100% green, pedal powered (for the most part!), electric tour boat based in Murrels Inlet, South Carolina.


Here's a copy of the email enquiry we received from Charlie:



"Hi, I have a USCG inspected vessel in S.C. that uses a Torqeedo 4.0 motor. I am trying to find a solution to stretch our range and power capacity for our 48Volt system. We are gearing up for our fourth season with the same motor/battery setup and have made it work but most days, just barely. We have a large canopy with plenty of room for panels. Thank you!"



We were pretty excited about this one and the SunPower flexible solar panels are a perfect solution: lightweight, flexible & powerful. For an electric boat, in this case they have a Torqeedo 4.0 Cruise motor, by adding solar you can charge the batteries whilst underway and help extend your range and time on the water, bonus!


After several emails and phone calls to discuss the best layout for the SunPower E-flex solar panels that would a) physically fit and b) provide the right amount of power for their needs they went with 8x170W and 4x110W SunPower E-flex solar panels. This is a total system size of 1,800W (1.8kW) and so for a 48V battery bank is potentially up to around 37amps.


Watts / Volts = Amps or use the handy triangle to remember:




The panels are wired in 3 strings to some Victron Energy MPPT 150|35 solar charge controllers that are suitable for 48V battery banks. The SmartSolar range has built-in bluetooth monitoring so you can see the system performance in great detail from the VictronConnect app on your phone/tablet.


One of the limitations is that Charlie was prevented from using Lithium-ion batteries by the US Coastguard and so had to go with AGMs which meant more solar panels and less battery capacity - with the idea to directly use the solar power in the daytime (when running their tours). The alternative, if allowed, would be to have less solar panels and store more power in the larger capacity Li-ion batteries.

Before adding the SunPower flex solar panels Charlie used a 110V-48V battery charger and would plug in every night so they could start a day with a full charge. As mentioned in his emails they would nurse the boat/motor during the day and just barely make it back to the dock. I think this is a great example of what's known as 'range anxiety', am I going to make it to the next dock to recharge. Check out our news story on range anxiety.


Since adding solar we had an update from Charlie they haven't plugged into shore power for over 3 weeks, are running multiple tours each day (5-6) and haven't seen the batteries drop below 80%, happy days. Guests really enjoy the quiet experience aboard, there's no more range anxiety from the captain and the batteries are maintained in a better condition.



If you have any questions about going solar on your Cycle Boat or have an electric motor aboard your boat and would like some info about how solar can help you extend your range and time on the water then shoot us an email we would be glad to help.