SOLAR PANELS F.A.Q.

What type of solar panel do I need?

SUNBEAMsystem offers high-efficiency, lightweight panels ideal for boats and vehicles. Space is often limited, so our panels are designed to deliver maximum output per square meter.

  • Panels with a Flush power cable offer a completely flat installation without protruding junction boxes—perfect for seamless, nearly invisible cabling.
  • Tough models are built for extreme durability and long life, meant for maritime use.
    . Tough-IQ with built in microchips is the perfect choice for anyone in need of serial connections and for longevity in shadow rich environments.
  • Carbon models are designed specifically for use on canvas (sprayhood/bimini)
  • Fold models are suited for temporary use when extra power is needed.
  • Maxa models offer a strong quality / price ratio for use on campers and RV’s.

Where should I install the panels?

Space is key. Use all available flat surfaces:
On boats: our Tough panels are walkable, allowing installation in areas otherwise unused.

  • On RVs: consider the roof, sides or awnings.
  • For canvas surfaces (e.g., tents or biminis): use Carbon models.
  • Use multiple smaller panels around obstructions rather than one large panel.
  • In shaded environments, split panels across multiple MPPT controllers for better performance.

Note: Most panels are meant for permanent installation. Using them temporarily may reduce lifespan or void warranty. For portable needs, choose Fold models.

IMPORTANT: Verify if your intended place or surface is suitable for installing solar panels.

You can find the mounting requirements in our Orientation Guide (click here to download PDF)

How do I calculate the ideal panel size (v advanced)?

1 – Estimate your 24-hour energy use
(e.g., fridge + lights).
Example: Fridge (1.9A × 18h) + Lights (0.3A × 3h) = 35.1 Ah/day

2 – Estimate daily effective sun hours.
Example: Sweden = 3 midday hours × 0.7 + 6 early/late hours × 0.5 = 5.1h

3 – Calculate needed current:
35.1 Ah ÷ 5.1h ≈ 6.8 A

4 – Convert to watts:
6.8 A × 13V = ~88W minimum solar capacity

Oversizing helps with cloudy days or growing power needs.

SOLAR PANELS - INSTALLATION

IMPORTANT: Before you proceed with installing the panels, please verify if the intended location is suitable for the type of solar panel you want to install.
You can find the mounting requirements in our Orientation Guide (click here to download PDF)

1. Calculating cable dimensions

Depending on your installation and vessel you need to run extension cables from the solar panels to the MPPT’s. The required dimension of your cabling is dependent on both the length of the cables and the amount of current (Ampere) that runs through them.

There are multiple free online DC Cable Size calculators available online that you can use for your specific situation.

Example
A Tough 111W panel puts out 18.56V (Vmp value) and 5.97A (Imp value) in ideal circumstances. These Vmp and Imp values are listed for every model.

If we assume:

– a source voltage of 18.5V
– a current of 6A
– a copper cable
– a maximum of 3% in voltage drop
– and a one-way distance of 6 meters

Then one Tough 111W panel would require a 2.7mm2 cable to bridge 6 meters of length. We choose a 4mm2 cable here.

If you run two Tough 111W panels, connected in parallel, over a length of 6 meters, it would require a 5.3mm2 cable. We choose a 6mm2 cable.

Rule of thumb: we advise to use a minimum 6mm2 cables in most installations to avoid unnecessary losses, but sometimes 4mm2 can suffice.

2. Connecting cables

Our panels come fitted with one of the following two cable connections:

Waterproof Sun-Click Connectors

These are prefitted cables and are suited for exposed outdoor use. They can be connected to a Extension cable with Sun-Click Connectors (available in 3, 6 and 10 meters length). We also have Sun-Click-T connectors available for easily connecting two Waterproof Sun-Click Connectors panels in parallel before connecting to a Extension cable with Sun-Click Connectors.

A flat Flush power cable

Our flat power cable is unique and allows for a cable-less installation with a Flushed end result. The main application is to run the cable through the deck or roof underneath the panel itself, ensuring no parts of the cable are exposed.
When the cable is inside a dry environment it can be connected to other panels and/or to extension cables running to the MPPT. Extension cables are often round, leaving the following options for interconnecting flat and round cables:

a. Wago Compact Lever Connector (0.5 to 6mm2). Fold the end of the flat power cable to obtain a square cable end. This can be inserted into the Wago Connector, as well as any round extension cables. A 3-way connector will allow for connecting two panels in parallel to a single extension cable.

b. Soldering connections. This will offer the safest and most waterproof connection if heat shrink wrap is applied over the connection.

c. Cable screw terminals. Make sure to buy a screw connector suitable for cables up to 6mm2.

3. Planning multiple panels

Parallel connections

Connecting multiple panels in parallel to a single MPPT controller offers both the highest daily yield aboard a yacht as well as the highest panel longevity. Any of our models can be put in parallel to a single MPPT as long as the Vmp value of the panels is within 1V of each other.
Please ensure that the capacity of the MPPT is suited for the total wattage of the solar panels combined. Example: a MoonRay 320 can accept a maximum of 320W on a 12V system (640W on 24V).

Serial connections

Note: For solar panels installed on a non-moving vessel it’s sometimes advised to install solar panels in series. For installations on moving vessels we always advise to install panels in parallel for the highest daily yield and the best panel longevity.

Only our IQ models are suited for serial connection. These feature a smart internal microprocessor that protects the cells against partial shading effects and improves overall production yield.

Only the exact same model can be connected in series. It’s not possible to connect two different models in a single serial string.

2S2P – 2 panels in series, 2 groups in parallel
This schematic is suited for installations with large amounts of panels that are not expected to experience a lot of partial shading on the solar panels. It allows for connecting a higher amount of solar panels to a single MPPT. In any other scenario we advise to use more MPPT’s with a smaller amount of panels per MPPT to safeguard optimal production.
For this schematic only IQ models can be used since they require a serial connection.

4. Charging 24V/36V systems

To charge 24V or 36V batteries a higher charger voltage is needed. There are two options:

1. Superior method
Connect panels in parallel using a (MoonRay) Boost MPPT. This will boost the charging voltage while maintaining the advantages from parallel panel connection

2. Secondary method
Connect up to 3 of our IQ models in series to any MPPT

5. Charging 48V systems

To charge 48V batteries connect panels in parallel and use a Boost MPPT. Our MoonRay Boost MPPT is programmable to your batteries charging profile.

It’s not possible to put 4 panels in series.

BATTERIES

We offer three distinct battery series:

– Plug & Play models – these offer high-performance cylindrical cells and are designed to be a fully Plug & Play replacement for your current household batteries
– Prismatic models – these offer the same functionality as our Plug & Play models but are equipped with more economical prismatic cells. These are also designed for replacement of your household batteries.
– DRIVE models – are developed specifically for electric propulsion applications. Available in a variety of different voltages (up to 48V) and capacities (up to 10kWh) and available with both prismatic as well as cylindrical cells.

Will the battery cut off when full? Will this harm my alternator?

No. The battery is fully Plug & Play and won’t damage your alternator or charger. It signals charging equipment to stop normally—just like a full lead-acid battery would.
Only in case of a fault (e.g., short circuit) will it isolate itself for protection. Read more about Plug&Play batteries uniqe gentle cut off Built for Winter: How Stainless Power Matrix Batteries Overcome the Cold – SUNBEAMsystem

Do I need to upgrade my alternator or install an electronic regulator?

No. Your existing alternator is compatible. While an electronic regulator offers more precision, it’s optional and generally not worth the added cost or effort for most users. Read more about this here Smart Lithium Long Term Field Testing – SUNBEAMsystem

Can I keep my current solar charge controller?

Yes, as long as desulphation/equalization modes are disabled. Set your controller to Gel/AGM mode to avoid this (or a LiFePO4 profile if available). Occasional equalization voltage (up to 14.6V) is not harmful, but pulse equalization might be. Better safe than sorry—disable it.

Do your batteries work in cold?

YES on the contrary to other LFP batteries our batteries work in cold weather even without energy wasting heaters. Read more about it here. Built for Winter: How Stainless Power Matrix Batteries Overcome the Cold – SUNBEAMsystem

Can I use an old garage charger from the ‘90s?

No. Old analogue chargers without regulation are unsafe for lithium batteries. Use only regulated or at least 2-stage (digital) chargers.

What is the maximum charger size I can use?

The charger’s current rating should not exceed the battery’s combined continuous charge limit.
Example: 2 x SMART LITHIUM ONE 12Ah = 2 × 240A = 480A max.

Do I need to trickle or maintain charge the battery?

No. Unlike lead-acid, lithium batteries don’t need trickle charging.
For storage during periods of a month or longer:

  • Disconnect chargers
  • Install a switch to isolate the solar controller (Moonray controllers have a storage setting you can use).

Can my alternator overheat from fast charging?

No. Despite internet claims, lithium batteries don’t overwork your alternator. Charging current is self-limiting due to system constraints (RPM, resistance, wiring). In practice, alternators output only 50–70% of their rated power.

You can safely install up to 400Ah of SMART LITHIUM capacity at 12V (or 200Ah @24V) without needing additional equipment.

Your charger can get hot during longer charging, especially at RPM’s that are around idle (when power is being generated but mechanical alternator cooling does not work optimal). This is the same scenario when you install a large capacity of lead-acid batteries.

When installing more than 400Ah @12V (200Ah @24V) we do recommend installing an alternator charge controller or a DC/DC charger to limit the current when charging with the alternator for hours on end.

Read more about the technical part here Smart Lithium Long Term Field Testing – SUNBEAMsystem

Can I use lead-acid batteries alongside lithium?

You cannot install lead-acid batteries in parallel to lithium batteries in the same battery bank. E.g. one SMART LITHIUM + one existing lead-acid battery as a household battery bank is not allowed.

What about my lead-acid starter or winch battery?

No problem. You can keep a lead-acid starter or winch battery in the same circuit (with the household battery being a SMART LITHIUM) when these are kept apart by a battery separator or relay/diode.

Will your cell inside the batteries swell?

NO our batteries have round cells fitted in a stainless steel cage. Other types of batteries may be prone to swelling. Read more about different battery types here Comparison of Lithium Iron Phosphate (LiFePO₄) Battery Cell Technologies for Marine and Mobile Applications – SUNBEAMsystem

Charge controllers

Standard vs. MPPT: Which to choose?

We advise you to always opt for a MPPT charge controller. These will offer the highest daily yield, especially in situations where partial shading is prevalent (almost always the case aboard yachts).

Choosing an MPPT Controller

Most MPPTs are optimized for serial connections because they are developed for allround use (including stationary / non-yacht applications), but:

  • Series: higher wear and tear on the solar cells (especially in partial shading)
  • Parallel: Longer life span and better partial-shade performance

Recommendation: Choose a controller optimized for 17–23V input, like MoonRay, for best parallel performance on moving vessels.

If you are charging a 24-48V system then MoonRay Boost will be the best choice. This MPPT offers all the benefits of connecting panels in parallel while boosting the charging voltage on the battery side.

Do MPPTs need higher voltage to start charging?

Yes, many MPPTs need 5V above battery voltage to activate charging (e.g., 17.5V to charge a 12.5V battery). This delays charging at the start of the day or after a cloud passage..

MoonRay MPPT’s do not require this extra voltage and start charging earlier. They are specifically designed to be the optimal complement for our panels on installation on moving vessels.

Sizing the Controller

Controllers are rated on the amount of peak wattage they can process at a certain battery voltage. Example:

MoonRay 160
– 160Wp of input on 12V
– 320Wp of input on 24V

Overpowering: Most controllers shut off if PV input exceeds the limit.

MoonRay handles slight overpowering safely by dissipating excess power as heat.

Large Installations = Multiple Controllers

For best performance, group similar-condition panels per controller. Different shading or angles between panels reduce efficiency when sharing one MPPT. In other words, group panels on starboard on one MPPT and panels on port side on another MPPT.

Use multiple MPPTs for optimal performance – MoonRay supports this, and Multi Connect merges data for easy monitoring. By dividing the total amount of solar panels over multiple MPPT’s, you obtain a modular system that is resilient to partial shading on part of the PV array.

Battery Compatibility

  • Most controllers support sealed lead-acid batteries
  • Check compatibility if using AGM, Gel, or Lithium batteries
  • MoonRay MPPT’s feature preprogrammed charging profiles but also offer the option of programming a custom profile
  • SMART LITHIUM by SUNBEAMsystem works without special settings

Using with 24-36V Systems

To charge 24V or 36V batteries a higher charger voltage is needed. There are two options:

1. Superior method
Connect panels in parallel using a (MoonRay) Boost MPPT. This will boost the charging voltage while maintaining the advantages from parallel panel connection

2. Secondary method
Connect up to 3 of our IQ models in series to any MPPT

Using with 48V Systems

To charge 48V batteries connect panels in parallel and use a Boost MPPT. Our MoonRay Boost MPPT is programmable to your batteries charging profile.

It’s not possible to put 4 panels in series.

MPPT Efficiency Matters

Many MPPTs perform well only in a narrow range. MoonRay offers a flat, high-efficiency curve across all power levels – ideal for real-world conditions with variable light.

Will the controller interfere with other chargers?

No. It works safely alongside alternators and shore power chargers without conflict.

Winter Storage Tips

In winter, lead-acid batteries need float charging. Solar is ideal if there’s enough light.
Avoid controllers with high self-consumption—MoonRay has low draw and is ideal for storage.

LiFePO4 batteries do not require a float charge. During winter it’s best to fully disconnect the battery from the circuit. Or if you have an Moonray you may set it to storage mode.