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Date: 6 June 2014. Solar Regulators (Standard vs. MPPT)


Living off the grid often means making sacrifices, but I'm not into that nonsense. Not at my age. I want and expect to have my indulgences and power plays a part in my happiness quotient. Solar panels and the regulators that go with them make a difference.

A fellow asked what he should do to get rid of the generator on his boat and live life off the grid. I've been living on the hook for a while and am almost at a suitable level of decadence. Though not quite there yet, I am closing in. Because I do not live life tied to a dock it is imperative that I generate power.

The first thing I did was buy an Air-Breeze wind generator because on the east coast there were a lot of sea breezes starting at 10 a.m.  On the Gulf coast I'm finding my wind generator less useful than elsewhere. 

Still in all, I'm glad I have it. If the sun doesn't shine often the wind does blow. And in the night those winds are charging my battery bank. That is a good thing.

Next I added a 75 watt solar panel and a Morningstar10 solar regulator. I later upgraded to a Morningstar30 regulator. The small panel wasn't enough. This past year I added two more 100 watt panels and I'm closing in on perfection. I like this regulator far better because of the information provided on the screen.

Morningstar ProStar-30 solar regulator

I bought the ProStar-30 a few years back and it is still functioning perfectly. Though often folks stash these in the bilge I chose to mount mine in the galley by the dinette so I can read the figures.

That's a West Marine cigarette lighter outlet to the right of my regulator, in case you wondered.
I have a few of those onboard Seaweed. See
What Used Boat? article for proof positive.

  • The Morningstar ProStar-30 has three numbers that slowly cycle through. The first two interest me.

  • The initial shows my Battery Voltage. 

  • The second number that flashes is the incoming Solar Amps.  I like when that number goes double-digit.

  • The third is Load Amps, but nothing is hooked to that as of yet.

  • The bottom left corner has a green LED that indicates when power is incoming. It is surprising how little daylight is required for power to be generated.

  • At the bottom right are three lights, Green, Yellow, and Red.  Green is Good!


There are slight differences in the meaning of those Green-Yellow-Red lights when charging versus after dark but essentially this is what you need to know:

Green Flashing Solid Green Yellow Red
Absorption charge or
float stage (trickle charge)
70% to 100% charged  30% - 70% charged below 30% charge

For more information, visit http://morningstarcorp.com - they are the experts.


Though I like my Morningstar30, if I didn't have real estate and was limited to the number of panels I could fit up top, I'd have opted for an MPPT regulator. I still wish I had one.

Here's what I've seen/read regarding the differences between them:

Backing up a bit... My latitude is 30 degrees, give or take. Think FL and GA border. From my solar panels I get approximately 100 amp hours per day.

Take solar panel wattage, divide by 3 and call it amps -- you can get fancy, but that's the number with a standard regulator that I'm seeing this far from the equator. This was confirmed by an EE with a penchant for precision. I think all Electrical Engineers have that trait.

However, there's a fellow up in WA state and he's got the MPPT* regulator. He's getting the same figures as me (watts divided by 3 equals amp hours) at his latitude.

*MPPT: Maximum Power Point Tracking (a type of solar regulator)

That's the difference in a nutshell: He's getting the same amount of amp hours into his batteries as me, although he is over 1000 miles north of here.

Thus, if you have real estate (lots of flat space) you could do as I did and opt for the less expensive solar regulator. On the other hand, if space is limited, I believe you should buy the more expensive but better MPPT regulators.  If money were no object, I too would have an MPPT. They really are the best.

That said, if your boat has a generator already I would not be so quick to shut it down. I've been aboard a Manatee with the genny running and couldn't hear it over the sound of the ice cubes in my glass.

Don't be so focused on getting it all right power-wise that you forget to live the life. Get out here and play for a while and soon enough your desires will determine what is next to fix/upgrade or switch to.

But live with what you've got at first. There's a reason your boat was outfitted as she was. Perhaps it's not apparent today, but in six months you'll know for certain. In the meantime add batteries, a great charger, and live with your generator.

In my opinion that is.  

Do you have solar panels as part of your charging system?
And, what type of regulator did you choose?

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