Question 1

Where can we find you?

Accepted Answer

Sun Powered Yachts is based on the Big Island of Hawaii and we have returned to landlife after 15 months living aboard our sailboat, a Dufour 382.  We sailed from Corsica to Cancun, crossing the Atlantic with the ARC 2021 sailing rally and exploring the Caribbean and Central America during 2022.  We then sailed to Key West and on to the Bahamas.  We had two seasons in the Bahamas and more recently sailed to the Chesapeake Bay in 2025.

Currently we are back in Hawaii.  
  
We're happy to answer any questions on the phone & email about sailing and going solar aboard your yacht.

Question 2

Can I charge my 24V or 48V battery bank with solar?

Accepted Answer

Yes.  Most solar MPPT charge controllers move power from higher voltage solar panel(s) to a lower voltage battery bank.  These are called 'buck' controllers and the full range of Victron Energy SmartSolar MPPT charge controllers are 'buck'.  So you need to have a solar panel array voltage that is greater than your battery voltage. 
 
The Victron MPPT controllers will auto detect what battery voltage they are connected to ie. 12V, 24V or 48V
 
In contrast, if you didn't have the 'roof space' to have a large solar panel array then you may have a lower voltage panel that would need a 'boost' controller.  This will take lower voltage solar panel(s) and boost it up to charge a higher voltage battery bank.  
 
A good example is the Genasun GVB-8 (boost) controller.  If charging a 36V-52V nominal battery bank, the GVB-8 (Boost) controller is ideal with any SunPower flexible solar panel.  Please check the spec sheets for detailed parameters or visit Genasun online

Question 3

My electric motor has a high voltage battery bank, can I charge with solar?

Accepted Answer

Yes.  We are confident that we can help you find a solution to charge your battery bank with SunPower solar panels.  Some brands of electric motors require higher voltage battery banks eg 96V or 108V and your typical MPPT controller will only go up to 48V.  We have worked on a few projects now with Elco and Torqeedo to find a solar charging solution.  Please email us and we can help you with your project and in our shop we have a high voltage charge controller manufactured by AERL in Australia.

An Elco EP-50 electric outboard requires a 96V (nominal) battery bank which requires a specific high voltage MPPT charge controller.

Question 4

What is Light Induced Degradation (LID)?

Accepted Answer

This is a loss of performance (1-3%) of brand new panels when first exposed to sunlight.  Fortunately SunPower® flexible solar panels are NOT effected by LID and as such retain their high levels of performance (efficiency).  The simple answer why is that the silicon used in the SunPower® cells is of a different type.  SunPower uses n-type silicon and only p-type silicon found in conventional panels is effected by LID as it is boron-doped and suffers from the boron-oxygen effect when first exposed to sunlight.  Yet another reason why SunPower is better.

Question 5

What is a conventional solar cell/panel?

Accepted Answer

A conventional solar cell is easily recognised by the thin metal lines that are on the front of the solar cell (cells on left of image)  These thin metal lines are usually a cheap, aluminum paste which reflects the sunlight, covers the active solar surface of the cell & due to being porous is susceptable to moisture corrosion.  This all contributes to the lower efficiency of the conventional cell which is typically around 15%

SunPower cells by contrast are easily recognised by an absence of metal lines on the front and have a solid dark appearance (cells on right of image)  There is nothing blocking the active surface as the contacts are allprotected on the back of the cell.

Question 6

Should I keep my panels clean?

Accepted Answer

The more sunlight that hits a panel, the more power it generates.  Typically panels are self cleaning with normal rainfall.  However, on your yacht, they are more prone to bird droppings and a build-up of general dust and dirt that does not wash off with just rain.  Therefore,  we recommend periodic cleaning of your E-Flex panels with non heated water, mild soap and a soft sponge to wipe the surface clean in a circular motion.

Question 7

Can I recycle my old solar panels?

Accepted Answer

A. Absolutely.  As many fixed solar panels are now coming to the end of their lifecycle (20-25 years+) we are starting to enter a time where more and more solar panels will need recycling.  This is the same for the newer flexible solar panels and it's important to recycle and keep solar panels out of landfill.  SunPower has been committed to being a responsible producer and provides appropriate reuse and recycling options for their products.  SunPower is a Founding Member and on the Board of Directors of PV Cycle for more info check out www.pvcycle.org contact your local SunPower dealer or email us and we'll help you recycle your old solar panels.
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Question 8

I have a Watt&Sea, can I connect solar panels to my controller?

Accepted Answer

After chatting with the very helpful tech support at Watt&Sea we have the following info:  
 
Since 2014 the Watt & Sea hydrogenerator charge controllers can also receive solar input.  The minimum PV voltage input is 7.5V, maximum PV voltage input is 50V & maximum amps input is 14A.  So as long as you stay within these parameters you are OK.  
 
It is worth noting that the controller will only charge your batteries from one source at a time (hydro OR solar) NOT both at the same time.  So when your hydrogenerator is not in the water/spinning to create hyrdro then it will recognize the solar input.  An alternative option may be to install your own MPPT charge controller just for your solar panels.  
 
The Watt&Sea controller also has the ability to charge two battery banks (ie. your house bank and engine start battery) as long as they are the same voltage (both 12V or both 24V)

Question 9

How can I calculate Amps?

Accepted Answer

Use the magic triangle below to calculate Amps, Watts or Volts.

Watts = Volts x Amps      (eg. 100W = 17.1V x 5.9A)
Amps = Watts ÷ Volts      (eg. 5.9A = 100W ÷ 17.1V)
Volts = Watts ÷ Amps      (eg. 17.1V = 100W ÷ 5.9A)

Question 10

What is Affirm and Sezzle?

Accepted Answer

Both Affirm and Sezzle are options at checkout that allow you to spread the cost of your purchase over a number of months with zero interest if it's paid off in full.  We can also email you an invoice and then just select to pay with either Affirm or Sezzle.  You then have to set up an account with them and you are on your way to enjoying clean & quiet solar power.

Question 11

Can I mix solar panels of a different wattage, eg. 110W and 170W?

Accepted Answer

Yes you can, BUT it is not ideal and certainly needs more attention and thought before setting up.  It is certainly better & recommended to wire together panels from the same manufacturer and the same panel wattage (or wire individual MPPT charge controllers) 
 
If you do plan on wiring dissimilar panels, you should know that:
 
a) For series connection – the same current rating of the panels is more important
b) For parallel connection – the same voltage rating of the panels is more important
 
So as an example if you only had space for 1x110W panel on the dodger and 1x170W panel on the bimini then first I would recommend seperate charge controllers for each panel.  If however you did want to go ahead and wire them together then you should look at the spec sheets and see if the current rating or voltage rating are more similar (closer together in value).
 
The SunPower 110W is rated at 18.8V and 5.9A
The SunPower 170W is rated at 29.4V and 5.84A
 
As the current rating is very similar (0.06A difference) then in this example we would wire 1x110W & 1x170W together in series.  However it's worth noting that performance will only be as good as the weakest link.  So in this example both panels will only produce 5.84A - the current rating of the 170W panel, which is the lower of the two.

Question 12

What size MPPT charge controller do I need?

Accepted Answer

Have a look at our install page where you will find the range of Victron Energy SmartSolar MPPT charge controllers.  Each has a max PV for the input, but it's important to look at some other parameters.  
 
75|10 - $109.80 - PV Input:
12V - Up to 145W
24V - Up to 290W
36V/48V - N/A
 
Feel free to email us and we can help size the correct controller for the number of solar panels and battery bank voltage you have aboard.

Question 13

Who is the ABYC?

Accepted Answer

The ABYC is the American Boat and Yacht Council, a voluntary standards creating body for the marine industry responsible for Standards and Recommended Practices. 
 
It's a great resource and we are proud to be a member, click here for more info on membership.
 
Visit their website to learn more www.abycinc.org

Question 14

How much power will I get from my panel?

Accepted Answer

There are more complicated ways to estimate how much power you are likely to get from your panel and performance will vary depending on weather conditions, shading etc.  But to keep it simple you can follow this trick to get a potential daily yield in terms of amp hours (for a 12V system):
 
For SunPower panels: divide the panel wattage by 3
For non-SunPower mono-panels: divide the panel wattage by 4
For non-SunPower multi-panels: divide the panel wattage by 5
 
So for the SunPower E-flex series of panels in a day and on a 12V system you could have a potential daily yield of:
 
50W divide by 3 = 16-17amp hours 
110W divide by 3 = 36-37 amp hours
170W divide by 3 = 56-57 amp hours

Question 15

Do you sell fixed frame solar panels?

Accepted Answer

Yes.  Since 2019 we have offered SunPower DC solar panels for sale to individual end customers to use on their boat or RV.

Since 2023 we now only offer Maxeon DC solar panels.  Visit our Fixed Frame page for more info.  Currently we are offering the 415W-R & 470W panels.

Question 16

How do you calculate daily yield?

Accepted Answer

On each of our solar panel product & bundle pages you will see in the description an idea of how much power you can expect from your panel of choice.  Here's an example from the 2x100W bundle:

How much power will I get? With a 12V system an estimated daily yield for a 2x100W bundle (200W total) is potentially around 64-68 amp hours

We are often asked how this is calculated, and it's a quick cheat:  You take the panel wattage and divide by 3 for Maxeon/SunPower cells to get an average daily yield in amp hours at 12V.

For non-Maxeon/SunPower you would divide by 4 as they are less efficient and so produce less power.  Other factors come into play such as Maxeon/SunPower cells are very good at handling shade & capturing power in low light conditions.

So 200W / 3 = 66Ah (at 12V)

We do it like this as most of our customers have a 12V battery bank and are familiar with their power usage and battery bank capacity in Amp hours (Ah).  If you do have a 24V or 48V battery bank there will be some different math and if you understand Watts better than again there is some different math that can be done.

Read our news post for more details on how this is calculated and the alternative way to get an answer in Watt hours

Frequently Asked Questions