Solar Panel Regulator Advice

newly anonymous · Jan 9, 2009

what Practical Sailor has to say

http://www.blueskyenergyinc.com/pdf/Practical Sailor PDF - Blue Sky Energy.pdf

Benny · Jan 9, 2009

Don't look at a gift horse in the mouth, but how old are those panels? As you probably know they loose the ability to convert sunlight to electricity over time. It would indeed make a difference if they were used or brand new. With the 3 panels you will need a controller to prevent overcharging on idle days. I did some rough calculations and came up with an average daily output of 75 amps. You may only get 5-6 hours a day of maximum intensity and not all days will be sunny so you should measure your ouput over a week's period and then average it to a daily figure. With your proposed budget you will still be running a deficit of at least 50 amps a day on an average day. You may still need that wind generator. I encourage you to do your homework and verify the actual output figures as well as your power budget so you will know exactly what to add or where to conserve. The price was right and with a relatively inexpensive controller of around 25 amps you will get some cheap amps.

John Nantz · Jan 9, 2009

Blue Sky Solar Boost 200E

The SB200E has been an excellent controller based on over 2 years of experience (since 2006).

My setup is with two Kyocera 130W panels for a total of 260W fed through the SB2000E into four golf carts and one Group 27 deep-cycle "start" battery. The battery monitor is a Link 2000.

The panels are rail mounted and hinged so they can fold down or be raised to about 25-degrees above horizontal.

SB2000E comments:

1. Digital readout is to 0.01 V or Amps which is very nice to see what is going into the system.

2. The unit is mounted below deck.

3. Low panel output: Output of panels is greatly improved over a direct solar panel connection because the controller increases the DC amperage when the panel output is greater than charging voltage, and just as important, when the charging voltage is BELOW the charging voltage.

Actually, in the Northwest, the latter advantage is MORE important because there can be so many days with rain, clouds, or overcast.

On one day when the rain was coming down steady and there were solid dark clouds overhead, the panels were still cranking out nearly 3 amps continuously, enough to actually keep the batteries from being discharged by the refrigeration.

4. Motor starting voltage: Motors like high voltage when they are started and batteries connected to solar panels really help provide the necessary high voltage to start them. This includes things like refrigeration, water pump, autopilot, and the forced air heater (this is the Northwest!). A high starting voltage with good amperage means the motors will last much longer.

Bottom line - there is no tough decision (unless there is a newer model as this one is 3 years old now), get the SB2000E.

The picture shows my mounting setup. The panels are adjustable for angle from -90 to ~+25

Bill Roosa · Jan 10, 2009

Solar considerations

Hi Nice-N-Easy
A couple of things to consider:
Count the number of "cells" on each panel. Make sure they are the same. If the gods are with you, you got the 36 cell type panel. If not then you are going to have trouble with heat in the summer (or down south) reducing the output to where it is not entirely useful. I know this is a problem for cruising where the electrical consumption is higher. There are controllers (yup the expensive ones) that can take a less than 36 cell panel and make it work through some of that electrical engineering magic. Something to do with pulses and duty cycles.
Make sure the charge controller can handle the FULL bright sun output of all the panels or buy multiple controllers. At 240 watts that would be 240/12=20 amps. 12 is the conservative figure 240/15=16 amps is more realistic but still over the 15 amps that most controllers are rated to. Don't you just hate it when the engineers get involved?

If you aimed the panels so the full output of all of them never occurred at the same time but you did get morning from one, noon from another, and afternoon from the third this may increase the net solar intake AND reduce the need for a greater than 15 amp controller. See, we engineers can be handy.:dance: For that to work at the dock you need to account for the "southern exposure" of the slip. An East-West bow-stern orientation being worst and North-South bow-stern being best or at least pleasantly aesthetic. That is a theory on my part so you have been warned.:Liar:
Check to see if the panels already have the diodes installed and if not get some to prevent them from sucking any AH they put into the batteries back out at night.
Also, I have an excel spread sheet that will do all the math for you energy usage on the boat. While not ready for prime time (I built it for me) it does let you play with the numbers without much fuss. william-roosa@us.army.mil

sailingdog · Jan 10, 2009

If you're not looking to go past these three panels, the BlueSky 2000E is probably a good choice of charge controllers. Best price I've seen on the controller is just a bit below $200, here. The BlueSky 2000E is a MPPT (Maximum Power Point Tracking) type charge controller and as such will generally give you about 20% more efficiency out of the panels by trading voltage for amperage when the panels are higher voltage than needed and amperage for voltage when they're lower than required for charging.

The really cheap charge controllers are going to waste a lot of the energy being created by the solar panels, and aren't worth the money IMHO in the long run.

If you're looking to get more panels later on, I wouldn't go with the BlueSky 2000E, since it is pretty much maxed out at 240 Watts of panels on a 12 VDC system. However, the next size up charge controller, something like the Outback MX60, is a good chunk of change. Another option is to parallel two BlueSky 2512i controllers (about $165 ea.), since they can communicate with each other and essentially act as a single charge controller.

A good compromise, if you don't want to pony up for the BlueSky 2000E, is a FlexCharge NC25A. While it is not a MPPT-type charge controller, it is a very good Pulse Width Modulation type controller.

BTW, I have two 130 Watt panels on my boat and the BlueSky 2000E.

Stu Jackson · Jan 10, 2009

Nice N Easy said:
I haven't completely finished a power budget yet, but am thinking between 50 & 75 ah per day, without a fridge. The fridge will more than double this I would think.

I can't comment on the controllers, Nice, what do you have on your boat that'd develop that daily load BEFORE refrigeration? It osunds altogether much too high. We run 80 ah a day with a fridge @ 60 ah a day, 5 amps when running, 24 hrs a day, 50% duty cycle once the food in the box is cold.

Good luck with your panels, a great way to go.

tsmwebb · Jan 10, 2009

This is a particularly interesting conversation to me. I'm waiting for customs to clear some replacements for faulty 80 watt panels on my boat. I've had four 80 watt panels and am using a simple controller (Ample Power). The useful output varies quite a bit but 4*80 seems to produce ~100 ah/day. That's a guess to be sure.

I'd far rather have more solar than a wind generator. But, if I were you I would test the panels you have before mounting them or buying an expensive controller. In my case, Kyocera is replacing my 80 watt panels with 85 watt panels. They no longer make the 80 watt panels.

The BlueSky controllers sound almost magical. Has anyone who does a bit of HF/HAM work lived with one? How horrid are they noise wise?

--Tom.