Adjustible Solar PV Controllers

[rgleason]

Due to this thread below and the observation that Solar Controllers tend to cut out before batteries are fully charged, we need to determine if some new controllers will be suitable and have adjustment of settings.

The dodger is small and two separate 50 to 65 watt panels are being planned. They will have two booster Genasun 12vd. Controllers because the panel voltages are too low. I dont believe these are adjustible however and I have not found any specifics about charging routine.

I understand Victron Bluesky controllers are fully adjustible with a shunt. Do they boost for 12v?

Depth of Discharge Myth? - Cruisers & Sailing Forums

[a64pilot]

I think you will find that you don’t need adjustable controllers.
I think you will find that even if locked into absorption voltage, the bank won’t quite reach fully charged by the end of the day.
I’d be so bold as to say that even reaching absorption voltage is rare, on a boat that is being actively used and not on a mooring.

[noelex 77]

Originally Posted by rgleason

Due to this thread below and the observation that Solar Controllers tend to cut out before batteries are fully charged

In my view, this is not accurate, if looking at absorption time, which seems to be the focus.

The absorption time is best set with reference to end amps. Assuming very long absorption times are appropriate for most (or all) solar systems is not correct.

Today was an example. We reached end amps at the very start of the absorption cycle. The ideal absorption time for this cycle was close to zero.

The charge voltage set points are often a little low, but these can adjusted on most regulators.

[Suijin]

Originally Posted by rgleason

I understand Victron Bluesky controllers are fully adjustible with a shunt. Do they boost for 12v?

They are adjustable in that they have presets for different types of batteries and the values for those are adjustable. Not sure what you mean by asking if they boost.

a64, I think it depends entirely on the setup. On a good sunny day I get to float by early afternoon. I have fewer watts solar than I do amp hours but don’t have a lot of load either.

[Paul L]

Originally Posted by a64pilot

I think you will find that you don’t need adjustable controllers.
I think you will find that even if locked into absorption voltage, the bank won’t quite reach fully charged by the end of the day.
I’d be so bold as to say that even reaching absorption voltage is rare, on a boat that is being actively used and not on a mooring.

It may be rare within the boats that you see, but it isn't among the cruising boats that I run across.

In your case with a 1000watts of solar I don't see how you couldn't reach absorption voltage.

On the OP, I think the Genasun controllers are the only boost controllers available. Maybe you should choose different solar panels so you can.use a standard MPPT controller.

[a64pilot]

It’s based on energy consumption, mine runs high as we don’t cut back or do much to try to conserve, within limits I have been determined to increase output as opposed to cutting back. Results are similar.
I, we watch too much TV I guess, and I’ve been recording everything for a year or two that we like to watch, just to have a movie library.
I expect when we do finally go to LFP, I won’t have any issues, and won’t have to run a generator for charging.
But running a generator twice a week for a couple of hours isn’t egregious to me anyway. To some it is.
As I have said, I hear seemingly the same people running their little Honda’s every day trying to get enough charge to get through the night. That would get old I think.
If we had been cruising for decades I’m sure we would act differently.
Same with water, we don’t conserve, we aren’t ignorant about it letting the water run while we brush our teeth or similar, but I even fresh water rinse our anchor chain as it comes up, and we flush with it too.

The thing about using a timer to determine when to drop to float is that is hit and miss, as even if your usage pattern is identical, many days are not.
The only ways I have seen work well are you watching amps and ending charge manually or having a system that will drop to float based on end amps at absorption.

Many days I will charge all day, and get quite a good deal of charge in, and never make it to absorption voltage. In fact I’d say that it’s not usual for us to spends hours at absorption voltage off of Solar.
If you are, well then you are using very little energy, have a large array or a small bank I would think, or some combination.

[newhaul]

Originally Posted by rgleason

Due to this thread below and the observation that Solar Controllers tend to cut out before batteries are fully charged, we need to determine if some new controllers will be suitable and have adjustment of settings.

The dodger is small and two separate 50 to 65 watt panels are being planned. They will have two booster Genasun 12vd. Controllers because the panel voltages are too low. I dont believe these are adjustible however and I have not found any specifics about charging routine.

I understand Victron Bluesky controllers are fully adjustible with a shunt. Do they boost for 12v?

Depth of Discharge Myth? - Cruisers & Sailing Forums

unless mounting area is really that small go with 100 watt panels .
I have never had a customer say they had to much power on the boat.
Pm me and we will see what we can put together that will serve you best.

[Paul L]

A64
Certainly better to use a controller that will drop out of absorption based on amps in. Our two controllers are older Blue sky and are easily programmable.

From the sounds of it we probably use a fair less juice than you do and we don't skimp. That's why I questioned you taking your experience and generalizing it to most cruisers. We have an approx 600ah AGM bank and 500 watts of solar. In good weather it handles most of our needs. On passages we run the genset an hour or so a day.

[rgleason]

On the OP, I think the Genasun controllers are the only boost controllers available. Maybe you should choose different solar panels so you can.use a standard MPPT controller.

Would like to but the best way is to have two panels port and starboard on the dodger, each to a boost MPPT controller such as Genasun boost, as I understand it.

unless mounting area is really that small go with 100 watt panels

. Yes, measuring from the centerline of dodger the size that fits nicely is 24"x23" but by going over the aft leather and sewing the velcro between/avoiding the zippers underneath, the two panels could be 24"x 24" or 24" x 25" or perhaps 24"x26".

I think you will find that you don’t need adjustable controllers.
I think you will find that even if locked into absorption voltage, the bank won’t quite reach fully charged by the end of the day.

I don't expect it to become fully charged typically until the 2nd day on the mooring. 225ah batts x 1.00-.85soc= 34amps. Say 70 watts (for both panels) /14.4v =4.86 amps. 34a/4.86a x 4.5 hour/day=21.8 amps/day.
34a/21.8a=1.55 days.

Bluesky - They are adjustable in that they have presets for different types of batteries and the values for those are adjustable. Not sure what you mean by asking if they boost.

Evidently, Genasun makes a GVboost controller that will also boost up voltage for the times when the small panel is not producing enough for higher voltages than 14+v so that the batteries can still be charged. These are more expensive but allow the use of the smaller panels.

The dodger panels are the first solar pv phase, then second stage would mount 2 bigger panels above the wheel on either side of the backstay similar to a bimini, on two carbon fiber 20mm tube frames that are adjustable angle in one dimension. I need to draw this up.

I also need learn more about how both genasun and bluesky controllers actually work and are adjustable.

Thanks, everyone all very good points.

I do get it that adjusting time is not a good way to do it, because our use varies and battery state also varies, so actually monitoring trailing amps with an accurate meter is probably best, but when I am not on the boat (when it is on the mooring) I need controls that will work well, fully charging the batteries to 0.05C trailing amps (less than 1.12 amps) for some time period (say 6 minutes) and then drop into float mode. That is important to not damage the batts.

[newhaul]

Originally Posted by rgleason

Would like to but the best way is to have two panels port and starboard on the dodger, each to a boost MPPT controller such as Genasun boost, as I understand it.

. Yes, measuring from the centerline of dodger the size that fits nicely is 24"x23" but by going over the aft leather and sewing the velcro between/avoiding the zippers underneath, the two panels could be 24"x 24" or 24" x 25" or perhaps 24"x26".

I don't expect it to become fully charged typically until the 2nd day on the mooring. 225ah batts x 1.00-.85soc= 34amps. Say 70 watts (for both panels) /14.4v =4.86 amps. 34a/4.86a x 4.5 hour/day=21.8 amps/day.
34a/21.8a=1.55 days.

Evidently, Genasun makes a GVboost controller that will also boost up voltage for the times when the small panel is not producing enough for higher voltages than 14+v so that the batteries can still be charged. These are more expensive but allow the use of the smaller panels.

The dodger panels are the first solar pv phase, then second stage would mount 2 bigger panels above the wheel on either side of the backstay similar to a bimini, on two carbon fiber 20mm tube frames that are adjustable angle in one dimension. I need to draw this up.

I also need learn more about how both genasun and bluesky controllers actually work and are adjustable.

Thanks, everyone all very good points.

I do get it that adjusting time is not a good way to do it, because our use varies and battery state also varies, so actually monitoring trailing amps with an accurate meter is probably best, but when I am not on the boat (when it is on the mooring) I need controls that will work well, fully charging the batteries to 0.05C trailing amps (less than 1.12 amps) for some time period (say 6 minutes) and then drop into float mode. That is important to not damage the batts.

with your listed size constraints the 5o watt flex panels are about your only options .

And considering your plans I would recommend getting controllers that can handle the expansion.

[Paul L]

There are many flex solar panels that are 18v and don't need a boost. Renogy for example.

[thomm225]

Originally Posted by rgleason

Due to this thread below and the observation that Solar Controllers tend to cut out before batteries are fully charged, we need to determine if some new controllers will be suitable and have adjustment of settings.

I plan to do an experiment.

Since I have installed my Victron MPPT Controller, my system is rarely at float in the morning whereas with my $18.00 PWM Controller it was still at 13.8 or so when I stopped by in the am after the voltage on the panel side read near VOC the day before

I now have both hooked up. A PWM controller and an MPPT. It will take a while for me to collect the data, but it should be interesting

My PWM is now only hooked up to one 20 watt panel but since I just received my Renogy 50 Watt Panel, I may have to hook that to the PWM controller soon

[newhaul]

My p30l doesn't have a float it just goes up to the voltage that is programmed and stops charging until I draw more power than the panels are putting out. Its a PWM controller I have not felt the need to change to an mppt yet it made more sense to buy more panels as long as there is real estate available . Batts are always charged by noon . ( I don't use diddly for power. )
heck this time of year at anchor I'm likely charged by 0900.

[Thumbs Up]

With an Outback mppt controller you can adjust every parameter and probably then some.

[noelex 77]

Originally Posted by rgleason

Evidently, Genasun makes a GVboost controller that will also boost up voltage for the times when the small panel is not producing enough for higher voltages than 14+v so that the batteries can still be charged. These are more expensive but allow the use of the smaller panels.

There are only a very small number of MPPT controllers that will boost voltage (and Genasun make one of these). They are designed to allow “6v” panels to be used in 12v systems or “12v” panels to be used with 24v systems.

Unless you have a special application where lower than battery voltage panels are needed, a conventional buck MPPT controller will be more efficient and is a better choice. As Paul has indicated, there are plenty of physically small “12v” panels to choose from.