MPPT charge controller installation for your boat — sized right, fused right, at your slip.
The controller is the part of a solar system that decides how much of your panels you actually get to keep. Fit the wrong one and a $2,000 array behaves like a $700 one. We size and install the
MPPT charge controller your boat actually needs, wire it to ABYC, and set the charge profile to your batteries — not to a factory default.
NMEA certified, fully insured, mobile across all of Long Island. When you call, you get the installer — the same person who sets the controller up and answers the phone afterwards.
Start Here
What an MPPT charge controller actually does on a boat.
Solar panels do not put out a tidy 12 volts. A panel rated for a 12-volt system might sit at 18 to 22 volts in the sun and climb higher when it is cold. Your batteries want something between roughly 13 and 14.6 volts depending on where they are in the charge. Something has to sit in the middle and manage that, and on a boat that something should be an MPPT charge controller.
"MPPT" is maximum power point tracking. Every panel has one spot on its voltage-and-current curve where it produces the most watts, and that spot moves all day — with the sun angle, with cloud, with how hot the panel is. An MPPT controller hunts for it continuously and converts the surplus voltage into extra charging current instead of throwing it away.
It keeps the surplus
Panel voltage above what the battery needs is not wasted — it comes back as amps into the bank.
It charges in poor light
Hazy mornings, low sun and shoulder-season days are where an MPPT pulls furthest ahead.
It protects the bank
The right charge profile for your battery chemistry, set against the maker’s data sheet, not a default.
The Real Difference
MPPT vs PWM — where the missing 30% goes.
A PWM controller is a switch. It connects the panel straight to the battery and pulses that connection on and off to hold the right voltage. Simple and cheap — but it drags the panel down to battery voltage to do it. Your 20-volt panel gets operated at 13 volts, and the difference is simply lost.
An MPPT controller is a converter. It runs the panel at its best point, takes the power, then steps the voltage down and the current up on the way to the battery. Nothing is thrown away.
- Typical gain: 20–30% more harvest from the same panels
- Weak light and cold: the gap widens — the times you most want the amps
- Long cable runs: MPPT lets you wire in series and run smaller cable
- Where PWM is still fine: one small panel trickling a 12-volt start battery
Put plainly: on anything above a single trickle panel, the controller is the cheapest place on the whole system to buy yourself more power. Bigger panels cost more and need more roof. A better controller costs a little and needs none.
Choosing The Unit
SmartSolar or BlueSolar — the one difference that matters.
Victron’s two ranges share the same charging engine. SmartSolar has Bluetooth built in; BlueSolar does not. That sounds minor until the first time something is not charging the way you expected and you have no way to look inside the controller.
With SmartSolar you open VictronConnect on your phone at the dock and see today’s yield, the history for the last 30 days, what the panels are doing right now and every setting. If something is off, we can often tell you what is wrong before we drive out. On a BlueSolar you are adding a dongle or a panel display to get the same view, which usually costs more than the difference did.
SmartSolar
Bluetooth built in. Live output, 30-day history and every setting from your phone. What we fit on nearly every boat.
BlueSolar
Same charging, no Bluetooth. Needs a dongle or display to see anything, which erases the saving.
With a Cerbo GX
Add a Cerbo and the controller reports to VRM, so you can see the panels from home — and so can we.
Getting It Right
How to size an MPPT charge controller for your boat.
Controllers are named for their two limits. A "150/70" handles up to 150 volts coming in from the panels and puts out up to 70 amps to the battery. Both numbers have to be right, and the voltage one catches people out.
1. The voltage side.
Add up the open-circuit voltage (Voc) of every panel wired in series. Then add headroom, because panel voltage rises as temperature falls — a string that reads 120 volts on a warm August afternoon can push past 145 on a cold clear morning in April. A controller taken over its PV limit does not warn you; it fails. We size against cold, not against today.
2. The current side.
Total panel watts divided by battery voltage gives you roughly the amps the controller has to pass. 600 watts on a 12-volt bank is about 50 amps. That fits a 150/70 with room to spare, and leaves you space to add a panel later without buying the controller twice.
3. The bank behind it.
A charge controller cannot make a tired battery bank hold charge. If the bank is at the end of its life, solar just hides the problem for a season. We check what you have before we quote panels.
Ready to talk? Or keep reading below.
Panel Wiring
Series or parallel — and why shade decides it.
Wire panels in series and the voltages add while the current stays low. That suits a long run from a hardtop down to the batteries, lets you use smaller cable, and gets the controller working earlier in the morning. Wire them in parallel and the voltage stays low while the current adds.
The deciding factor on a boat is usually shade. In a series string, the weakest panel sets the pace for the whole string — one panel under the shadow of a mast, a radar arch, an outrigger or a boom can pull the entire string down out of all proportion to the area covered. In parallel, that panel underperforms and the others carry on.
Boats move, and so do their shadows. We look at what actually falls across your panels through a day before we decide, and on a hardtop with a mast forward we will often run two strings on separate controller inputs rather than force everything into one.
The Workmanship
What a proper MPPT charge controller install looks like.
Most of the solar problems we get called out to are not the controller. They are how it was put in.
Fused on both sides
An inline fuse on the panel side and a correctly rated fuse close to the battery. The battery side is the one that starts fires, and the one most often missing.
A real isolation switch
You must be able to kill the array to work on anything. Panels are live whenever the sun is up — there is no off switch on a solar panel.
Cable sized for the run
Sized for the current and the distance, tinned marine cable, adhesive heat-shrink terminals, supported and chafe-protected the whole way.
Mounted to breathe
Controllers dump heat. Vertical, off the hull side, with clearance above and below — not buried face-up under a locker floor.
Set, then documented
Charge profile set to your battery’s data sheet, and the settings written down so the next person is not guessing.
Tested under load
We watch it charge before we leave, and check the whole run for voltage drop rather than assuming the cable is fine.
Charge Profiles
Lithium and AGM want different things from the controller.
A controller set to the wrong profile will charge your batteries. It will also quietly shorten their life, and on an expensive lithium bank that is a costly mistake to leave running for a season.
AGM wants a bulk and absorption stage at roughly 14.4 to 14.7 volts, a decent absorption time, then a float around 13.5 to hold it topped up. Leaving an AGM sat at float is fine — it is what it is designed for.
Lithium wants a lower absorption voltage, a much shorter absorption time, and ideally no float stage holding it full. A lithium bank stored at 100% all season ages faster than one cycled sensibly. The right numbers come from the battery maker, not from a generic "lithium" preset.
If you also charge from the engine, a DC-DC charger belongs in the picture too, so a lithium house bank cannot pull an alternator past what it was built for.
What It Costs
Time and materials — never a fixed price.
The first hour is a flat $280 for one installer. That covers travel to your boat up to 30 minutes each way, setup, and the first hour of work. After that it is
$140/hr, billed in 15-minute steps. There is no four-hour minimum and no separate trip or setup charge.
Swapping a controller and fusing it properly is usually two to three hours. Adding an array with new cable runs, isolation and monitoring is generally a day. Equipment is supplied by us at cost plus markup, itemized on your receipt — we do not install customer-supplied gear.
Everything is billed on the time actually worked. You pay for the job that got done, never a padded fixed quote.
ABYC Electrical Standards
Empire Wind NETP Approved Vendor
Fully Insured
$280 First Hour · $140/hr After
No Minimums
60-Day Labor Warranty
You Call, You Get The Installer
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FAQ
MPPT charge controllers on a boat — what owners ask.
What does an MPPT charge controller actually do on a boat?It sits between your solar panels and your batteries and does two jobs. It steps the panel voltage down to whatever the battery needs, and it constantly hunts for the point on the panel’s curve where it makes the most power — that is the "maximum power point" the letters stand for. On a boat that means the panels keep producing on a hazy morning or with the sun low, instead of falling off a cliff the way they do on a cheap controller.
It sits between your solar panels and your batteries and does two jobs. It steps the panel voltage down to whatever the battery needs, and it constantly hunts for the point on the panel’s curve where it makes the most power — that is the "maximum power point" the letters stand for. On a boat that means the panels keep producing on a hazy morning or with the sun low, instead of falling off a cliff the way they do on a cheap controller.
MPPT or PWM — is the extra money worth it?
On a boat, almost always yes. A PWM controller just connects the panel to the battery and throttles it, so a 36-volt panel charging a 12-volt bank throws away most of the difference. An MPPT converts that extra voltage into usable current instead. Real-world that is roughly 20 to 30 percent more harvest from the same panels, and more than that in weak light. The exception is a single small panel on a 12-volt trickle duty, where a PWM is fine and the price difference is not worth chasing.
SmartSolar or BlueSolar?
Same charging engine. SmartSolar has Bluetooth built in, so you see live solar output, history and settings on your phone through VictronConnect, and we can change the charge profile without pulling a panel off. BlueSolar has no Bluetooth and needs a dongle or a display to see anything. We fit SmartSolar on almost every boat — the price gap is small and the ability to look at what the panels are doing is the whole point of having them.
What size MPPT charge controller do I need?
Two numbers decide it. First, the controller’s maximum PV voltage has to be above your panel string’s open-circuit voltage in the cold, with headroom — panel voltage rises as temperature falls, and a controller that is fine in August can be over its limit on a cold clear April morning. Second, the output amps: panel watts divided by battery voltage. 600 watts of panel on a 12-volt bank is about 50 amps, so a 150/70 has room. We size with headroom on both, because a controller run at its ceiling runs hot and dies young.
Should my panels be wired in series or parallel?
Series adds the voltages and keeps current low, which suits long cable runs and lets an MPPT start earlier in the morning. Parallel keeps voltage low and is far more forgiving of shade, because one shaded panel does not drag the whole string down. On a boat with a mast, a radar arch or an outrigger throwing a moving shadow across the hardtop, parallel or a separate controller per string usually wins. We look at what actually shades your panels through the day before deciding.
Can you add solar and an MPPT to a boat that already has batteries?
Yes, and that is most of this work. The controller goes in near the batteries, the panels get a proper isolation switch and inline fusing on both the panel side and the battery side, and the charge profile is set to your existing bank. If the bank is tired, solar will not save it — we will tell you that before you spend money on panels.
Will an MPPT charge controller work with lithium batteries?
Yes, with the charge profile set to the battery maker’s specification, not the factory default. Lithium wants a different absorption voltage and a much shorter absorption time than AGM, and it does not want a float stage holding it full. Getting that wrong shortens the life of an expensive bank. We set it against the manufacturer’s data sheet and leave the settings documented.
What does an MPPT charge controller installation cost on Long Island?
Time and materials, never a fixed price. The first hour is a flat $280 for one installer, and that includes travel to your boat up to 30 minutes each way plus setup. After that it is $140/hr in 15-minute steps, with no four-hour minimum. A controller swap with proper fusing is usually two to three hours. A full array with new cable runs, isolation and monitoring is a day. Equipment is supplied by us at cost plus markup and itemized on the receipt.
Not sure which controller your panels need?
Send us the panel model and how many you have, plus a photo of the battery space. We will tell you what size controller fits, what it takes to wire it properly, and what it is likely to run.