Can I add additional power source(s) to Victron MPPT controller?

dlochner · Tuesday at 9:15 AM

Do not connect it to the controller. The controller expects inputs that are high voltage and low current, high voltage meaning at least 5v higher than the battery. The OB output will be about 12v and 3-5a. A definite mismatch.

I'm not sure how the OB's electrical out put would do with LFP batteries. This probably not a regulated output and may charge the LFP battery an inappropriate voltage. Small outboard DC out puts are designed to run lights and charge lead acid batteries.

jssailem · Tuesday at 9:18 AM

Greg,
I am a neophyte solar sailor. I have been studying the various options and asking a lot of questions.

I have the same MPPT controller. I understand you can have 2 90W panels producing 12V output to the controller.
Note that the max charging amperage is 15 Amps. Check your battery specs to see if that will meet the battery's charging requirements.

Here is a handy calculator from Victron.

MPPT Calculator - Victron Energy

www.victronenergy.com

dlochner · Tuesday at 9:24 AM

To answer the second part of your question, yes you can add a third panel to the controller so long as you do not exceed 220 nominal watts of input at 75v.

Whether you add the extra panel in series or parallel to the existing panels is a longer answer.

colemj · Tuesday at 9:49 AM

There is no problem exceeding the 220W input limit, but the output will be limited to 15A maximum. It is often desirable to over-panel the input a bit.

You cannot exceed the voltage limit without damage.

Mark

Nichole340 · Tuesday at 10:26 AM

Gene Neill said:
I have also long considered a "spare" flexible solar panel which could be stored under a mattress, to be brought out in benign conditions, and plugged into the system somehow.

Great Question, you’re asking what I have been thinking. Suggestions for a lightweight 50-100 Watt Flexible Solar panel and charge controller. Never thought about storing it under the mattress until I need it, but great idea.
I’m on a mooring so I would like to add a flexible solar panel that I can use to keep my 2-Duracell Ultra | 230AH | 6V | Golf Cart batteries, wired in series to create 12V charge and a Duracell Ultra BCI Group 31 12V Flooded Dual Purpose 700 CCA batteries charged while I’m not on the boat. Usually a week or so duration.
I don’t run the refrigerator or cabin lights, just the bilge pump, fresh water pump and VHF radio as needed. So it really is just to keep batteries charged between visits….my “benign conditions”
Pretty bare bones operation, charging batteries now is strictly motoring on and off the mooring and back and forth to the harbor. And occasional motor sailing.
Keep the ideas coming please.

Stu Jackson · Tuesday at 10:51 AM

Nichole340 said:
my 2-Duracell Ultra | 230AH | 6V | Golf Cart batteries, wired in series to create 12V charge and a Duracell Ultra BCI Group 31 12V Flooded Dual Purpose 700 CCA batteries charged while I’m not on the boat. Usually a week or so duration.

You only need to keep your house bank charging during the week you're gone so they will be full when you return. Your reserve bank, usually used for engine starts and when motoring out, is almost always full and can take a week resting without further charging. Unless you have a combiner or echo charger already installed, you didn't say. KISS.

JoeWhite · Tuesday at 11:42 AM

I have similar setup. I installed one 100Watt flexible solar panel fastened to the top of the dodger and victron 30 amp controller/charger. It is always on and the switch is on All when at the slip and on 1 which is the house batteries when sailing. It provides all the current needed for the instruments and charge the battery.
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dlochner · Tuesday at 11:51 AM

Flexible panels are not all that flexible. They are designed to attached to a curved surface like a hard dodger, cabin top, or hard bimini.

The connections between each cell in the panel are very fragile and repeated bending will cause them to break significantly reducing the panels out put or rendering it landfill.

One option is to mount the flexible panel on something firm, like ¼" starboard, a fiberglass panel or some plywood. This keeps the connectors from breaking, however, it may increase the panel's temperature which will reduce output.

dlochner · Tuesday at 1:28 PM

Gene Neill said:
The Victron manual suggests that using different wattage panels may result in the controller "not achieving full output". It does not go into detail as to how much output might be lost.

Perhaps I should invest in a second controller. It's not like they weigh much. And the redundancy would be a plus.

It probably depends on how they are wired. If you wired the 2 30w panels in series for one controller and the second one on another controller and the out put of both controllers in parallel to the battery, you would have a pretty robust system.

Wiring the 2 small panels in series with double the Voc (open circuit voltage) which will help get around Victron's 5v threshold. The big advantage is the panels will start making power a lower light levels, such earlier on the morning and later in the afternoon.

Getting a larger panel, say 60-100w and using a second controller will give you redundancy and by careful placement of the panel you have as many issues with shading. The larger panel will likely have a higher Voc so, production will be enhanced.

For your energy budget, figure the panels will produce 3x their nominal wattage on average if used sun up to sun down. Some days will be better, some worse. Higher quality panels will do better than lower quality panels.

colemj · Tuesday at 3:01 PM

Get rid of the 30W panels. Are these hard panels permanently mounted? If so, a 100W panel to replace them is $35.
Grape Solar 100W Monocrystalline Solar Panel for RVs, Boats, and 12V Systems

Then if you want a storable panel, get a 100W flexible and use the solar controller you have for both.
ALLPOWERS SF100 Monocrystalline Flexible Solar Panel 100W

For <$150, you now have 200W of solar. Of course, to use a single controller, you would want both panels mostly without shading. If that isn't possible, then another controller may be worth it.

FWIW, if there is any way you can go with hard panels over flexible, do it. Those 100w hard panels are only 32"x28". Even if you can't mount it, it might be easy enough to store below when underway. Flexible panels are the road to heartache, and will never match output of hard panels. If you do go that way, find something stiff to mount them one permanently - like that honeycomb polycarbonate sold for greenhouse.

Mark

...3TacksontheWater · Tuesday at 4:40 PM

Well, as I’m a land locked sailor, there is no doubt that we use our boats in different ways. My outings on Waffle House so far, are only day sails and only once, have I motored back in with Steaming light, full navigation lights and then I proceeded to use the deck light to draw as much power as I could. I have the same battery as you do Gene, it handled the load with aplomb. Yes, we’re both missing out on a charging opportunity with our Tohatsus not contributing to the charging system, but then again, how much drain does your electronic usage put on your system?

George

BarryL · Wednesday at 7:28 AM

Hello,

My boat is also on a mooring and I wanted a simple way of keeping the "house" battery bank charged when I was away from the boat. My solution was this:

https://defender.com/en_us/go-power-portable-solar-panel-kit-90w-gp-psk-90

It's super easy to store when not in use, deploy when away from the boat, and it puts out plenty of power.

Some things to note:
The charge controller is mounted on the solar panel. The solar panel will be out in the sun (and RAIN, because sometimes it rains). The charge controller is NOT waterproof and will fail if exposed to rain. After mine broke from getting wet I called and complained. Go power sent me a new unit. I drilled out the rivets holding the controller to the panel and moved it below into an aft cabin where it stays dry.
I used ring terminals to permanently connect the controller to the house battery bank.

When I get onto my boat I disconnect the panel, and stow it below, in it's case.
When I am done sailing i put the panel on a cockpit seat and connect it.

My house bank is always charged.

For this year I wanted to generate power while I was on board and sailing. I have bought 2 panels that I will mount on my dodger and I have bought and installed a Victron solar controller. The Portable kit will come off the boat and go into storage.

Good luck,
Barry

Nichole340 said:
Great Question, you’re asking what I have been thinking. Suggestions for a lightweight 50-100 Watt Flexible Solar panel and charge controller. Never thought about storing it under the mattress until I need it, but great idea.
I’m on a mooring so I would like to add a flexible solar panel that I can use to keep my 2-Duracell Ultra | 230AH | 6V | Golf Cart batteries, wired in series to create 12V charge and a Duracell Ultra BCI Group 31 12V Flooded Dual Purpose 700 CCA batteries charged while I’m not on the boat. Usually a week or so duration.
I don’t run the refrigerator or cabin lights, just the bilge pump, fresh water pump and VHF radio as needed. So it really is just to keep batteries charged between visits….my “benign conditions”
Pretty bare bones operation, charging batteries now is strictly motoring on and off the mooring and back and forth to the harbor. And occasional motor sailing.
Keep the ideas coming please.

Johann · Thursday at 8:50 AM

Gene Neill said:
The Victron manual suggests that using different wattage panels may result in the controller "not achieving full output". It does not go into detail as to how much output might be lost.

Perhaps I should invest in a second controller. It's not like they weigh much. And the redundancy would be a plus.

The panels should have a max power voltage (Vmp) and a max power current (Imp) rating on the label or in documentation. Wattage is Vmp x Imp. You can parallel panels with the same Vmp, regardless of the wattage of the panels. If you parallel panels with different Vmp, even if the wattage rating is the same, that is when you lose production. For example, take two 50W panels. One with a Vmp of 18V and Imp of 2.8A, and one with a Vmp of 25V and Imp of 2A. If you parallel them then the MPPT will end up around 18V so the 18V panel will produce 50W but the 25V panel will only produce around 36W. Of course this isn’t exactly correct numbers, just to illustrate the reason there is a loss.

JBP-PA · Thursday at 9:42 AM

Gene Neill said:
So, it looks like I still have no use for the outboard alternator, other than perhaps in the event of a catastrophic battery failure. With a little fiddling, it could at least power the nav lights and such.

As to the spare panel, "RTFM" finally crossed my mind.

The Victron manual suggests that using different wattage panels may result in the controller "not achieving full output". It does not go into detail as to how much output might be lost.

Perhaps I should invest in a second controller. It's not like they weigh much. And the redundancy would be a plus.

The only safe way to use your outboard alternator is to add a lead acid battery (AGM or FLA) to the alternator and use a DC-DC charger to charge your LFP. This works fine, but it might not be worth the small amount of power you'll get.

Having a spare panel is fine, but it is best to use a separate controller. Mixing and matching panels of different sizes doesn't give the sum of all panels and it can cause some panels to overheat. If they are close in specs, maybe. I carry one of the camping fold up suitcase type panels and have an extra 75/10 controller for it. As a bonus, the camping panels also provide USB, USB-c pd, and direct dc for charging lead batteries.

Can I add additional power source(s) to Victron MPPT controller?

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SBO Weather and Forecasting Forum Jim & John

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