mppt

[lbdavis]

New (to me) 90W panel going on the boat this off season as part of an electrical upgrade. This will be mounted shade free off the pushpit and will be feeding the house bank of two group31's. I'm on a mooring and do not "plan" on adding another means of power, e.g., wind or shore, beyond the aux/solar arrangement I will now have.

It came with a standard three charge regulator on it, but I am contemplating a mppt controller for increased efficiency.

Are the Outback and Blue Sea the only two options for the marine environment?

Do these chargers really increase efficiency as well as they advertise?

[Cruisingdad]

Yes, they work as advertised and are worth the money. However, unless you plan on adding more panels, you would be better advised to go with a Blue Sky (IMHO). THe Outback is really better suited for larger systems. Also, a 90w panel will probably only put out 35.5ah/day on a good day. Refrigeration alone pulls over 50ah. I cannot imagine that small of a bank running much on your boat. At best, it will be a small supplement.

If cost is an issue, I would push you to a wind gen as I think you get the best bang for your buck. I just do not like them as much as solar and a good solar arrangement is better than a good wind arrangement (and quiter!!).

These are my opinions only, so take them for what they are worth.

Go here for good and knowledgeable people to purchase from. IT is also tax free and competitively priced:

Electricity from the sun since 1

PS Noticed you are in Portland. I would really push you towards wind unless you plan to head south.

[waltsn]

I have the Blue Sky MPPT Blue Sky Energy INC. - Solar Boost 2000E with 160 watt panel and used it for a few years - a few years back. The display will tell incomming current and outgoing current and I beleive I was getting about an average 15% - maybe a hair more - extra current over a conventional pulse width modulated controller. Not as much as the litererature said but not bad either. I think to get the literature numbers, you need to be charging very depleted batteries at cold temps with a panel closer to the max rated current.

Seems like it still works fine after about 4 years but this is not in a marine environment.

[camaraderie]

Walt...your numbers make sense with what has been reported elsewhere. A 90 watt panel will typically put in about 25amphours/day and with an mppt should get around 30-35 depending on the latitude.

[bobmcgov]

Yep -- MPPT is da bomb, but its benefits are much reduced above 40 degrees F. Higher ambient temps reduce panel overvoltage down to near-faceplate numbers -- and it's that overvoltage that MPPT controllers use to advantage.

I get 15% improvement in summer, but when it's minus ten and the (nominal 24V) panels are running 39VDC at the bus, the gains are immense: up to 35%. On a boat, dunno. Suspect more raw surface area and a dumb controller is the way to go if you have room for another panel. You may be looking at $400 cost increase for MPPT.

[sailingdog]

Of course, keeping the panels cool is key to keeping their output at reasonable levels...they get less efficient as they heat up.

[lbdavis]

Thanks, gang.

I had already ruled the outback out due to co$t. The blue sea may be worth it to me. I'll have to do the math and weigh the importance and need for the added efficiency for my application.

My two group31's are plenty for me. There about three times my daily consumption when cruising. But sadly the boat sits at mooring during most work weeks.

I mostly want this panel to keep this bank topped off during the week. I like the idea of taking 3 or 4 day-sails in a row without ever turning on that damn motor. It would also be nice to supplement the alternator while cruising for a couple of weeks.