Adjustible Solar PV Controllers

[daletournier]

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.

This is true. Although mine are adjustable to hit float upon reaching end amps the reality is I never quite get there, close but not quite. I get close to 1%.

[john61ct]

In sizing for solar-only, the relationship between AH capacity and total panel watts is not so critical.

The key is your average AH usage per day, which must be say half of your panels' output, with LFP they can be closer.

______
If you are sitting at Absorb all the way to sunset and still not hitting endAmps

your bank may be getting old, revise your definition of endAmps to something more realistic, and/or

you need to reduce usage, or

increase your panels, or

burn dino juice in the morning before solar starts producing.

[john61ct]

Originally Posted by Thumbs Up

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

This is true for every decent SC, much more common than with shore chargers.

Are people here trying to get away with decades-old designs or $20 PWM Chinese SCs off eBay or something?

Several units coordinate with an AH-counting SoC meter so only drop to Float based on a direct reading of endAmps.

Yes more expensive.

The algorithms for Absorb Hold Time and Absorb Return are worth looking at, straight egg-timers are pretty dumb these days.

Victron's SmartSolar series is great value.

[john61ct]

Originally Posted by rgleason

50 to 65 watt panels are being planned.

That is tiny, really only useful IMO for the tail end of the long tail required by lead, 90% of your actual energy production off-grid will need to be from fossil fuels.

To get more realistic wattages, you may need to invest in bigger mounting structures.

Or going to LFP will allow you to skip solar entirely, which may well make up the price difference, and keep the boat clean.

> They will have two booster Genasun 12vd. Controllers because the panel voltages are too low.

Choose the controller, then panels to match, not v/v. Wiring panels in series on the same side can get you to higher volts.

If going semi-flex, you can order custom sized, e.g. very long and thin, if necessary.

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

First off two completely different companies, both excellent.

Being fully adjustable is one thing, very common.

A shunt implies integration with a BM, pretty rare.

[newhaul]

I have installed these panels on a few customers smaller boats and they are very happy with their performance and I like the price.
https://www.amazon.com/HQST-Monocrys.../dp/B017TPHTLG
Hqst is the flex panel division of renogy solar.
Sometimes I get them off fleby for a buck a watt.
Their 24 inch size will fit considering your placement parameters

[newhaul]

Here is an example to give you an idea as to the actual size
This is a San Juan 24.

[noelex 77]

Originally Posted by john61ct

This is true for every decent SC, much more common than with shore chargers.

The Victron controllers are great value, but the larger advanced controllers from companies such as Outback and Midnite have more adjustable algorithms. The greatest difference is that they calculate absorption time correctly, making it easier to customise the program, but there are many other differences.

A simple example is the wake up parameter that at a fixed +5v for the Victron has been criticised as little slow for 12v panels. With the Outback the wake up volts and even the wake up time is adjustable. There are many other differences such as adjustable battery return amps, adjustable equalisation time, MPP range limits and auxillary output options.

One of the big advantages of the Victron controllers is a low self consumption, making it more viable to use one controller for a smaller panel size, but the lack of processing power does mean you sacrifice some adjustability.

[mvmojo]

Originally Posted by Thumbs Up

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

We use an Outback FLEXMax FM80 MPPT controller with 1,000 watts of panels. There are a ton of adjustments in the controller, a handful of which I don't have a clue about (and haven't needed to take the time to learn about). I just leave them at the default setting. We produce ~300 a/h per day into 10 golf cart batteries and are at float most days by 2 or 3 in the afternoon. Couldn't be more happy with the setup. The MPPT controller gave us another 20%+ in a/h/day vs the old PWM controller.

[rgleason]

Very interesting about Victron mppt controllers linking via bt to 712 for using batt data V etc.

Genasun GVB-8-WP specs here
https://genasun.com/products-store/m...t-controllers/

[john61ct]

Color Control GX + BMV-712

Use VE Direct for comms

Also connections to FOSS protocols, tie into rPi / Arduino

[mitiempo]

Originally Posted by rgleason

Very interesting about Victron mppt controllers linking via bt to 712 for using batt data V etc.

Genasun GVB-8-WP specs here
https://genasun.com/products-store/m...t-controllers/

What is the voltage of your solar panels? The Genasun boost for 12 volt nominal banks appears to have a maximum panel voltage of 13.

I don't understand how that can work. The Genasun boost controllers are really designed to charge 36 or 48 volt systems.

One thing to keep in mind though is that with a smaller solar installations the batteries will not get to absorption until they are over 90% charged, often as high as 95% charged. Absorption time is really not an issue in this situation.

Battery banks will typically be about 80 to 85% charged with a larger charger.

[daletournier]

Originally Posted by mvmojo

We use an Outback FLEXMax FM80 MPPT controller with 1,000 watts of panels. There are a ton of adjustments in the controller, a handful of which I don't have a clue about (and haven't needed to take the time to learn about). I just leave them at the default setting. We produce ~300 a/h per day into 10 golf cart batteries and are at float most days by 2 or 3 in the afternoon. Couldn't be more happy with the setup. The MPPT controller gave us another 20%+ in a/h/day vs the old PWM controller.

Hi, what is absorption voltage set at? What is amperage acceptance just prior to dropping into float?

[noelex 77]

Originally Posted by mitiempo

One thing to keep in mind though is that with a smaller solar installations the batteries will not get to absorption until they are over 90% charged, often as high as 95% charged. Absorption time is really not an issue in this situation.

It is not commonly appreciated that the lower charge level is, the shorter the absorption time needs to be. People often get this wrong and assume a lower charge level will need a longer absorption time.

Solar outputs, especially the net output into the batteries, even from larger arrays, are typically lower than battery chargers. It is therefore often incorrectly assumed the absorption time with the solar controller will need to be much longer than their battery charger. The opposite is true.

This is why so many solar installations are better with a quite short absorption time, rather than the very long, or even continuous absorption times that are frequently recommended in the forum (but take the time to measure the voltage end points over a few cycles). This is especially the case when aggressive voltage set points are chosen. The latter is beneficial (although I would stay within the battery manufacturer’s recommendations) if you want to cram the most power out of the solar array in as short a time as possible.

[noelex 77]

Originally Posted by mitiempo

One thing to keep in mind though is that with a smaller solar installations the batteries will not get to absorption until they are over 90% charged, often as high as 95% charged. Absorption time is really not an issue in this situation.

Good point. It is not commonly appreciated that the lower charge level is, the shorter the absorption time needs to be. People often get this wrong and assume a lower charge level will need a longer absorption time.

Solar outputs, especially the net output into the batteries, even from larger arrays, are typically lower than battery chargers. It is therefore often incorrectly assumed the absorption time with the solar controller will need to be much longer than their battery charger. The opposite is true.

This is why so many solar installations are better with a quite short absorption time, rather than the very long, or even continuous absorption times that are frequently recommended in the forum (but take the time to measure the voltage end points over a few cycles). This is especially the case when aggressive voltage set points are chosen. The latter is beneficial (although I would stay within the battery manufacturer’s recommendations) if you want to cram the most power out of the solar array in as short a time as possible.

[conachair]

Originally Posted by noelex 77

This is why so many solar installations are better with a quite short absorption time, rather than the very long, or even continuous absorption times that are frequently recommended in the forum (but take the time to measure the voltage end points over a few cycles).

Not so sure "so many" - add house loads and a few clouds and a bit of shadow I would guess "so many" actually struggle to get back to 100% every day even with no float. Some fairly accurate logging of volts/amps would be needed to know for sure. This is 300W going into 2 x T105 down to about 80% overnight - no clouds but still not a done deal to get back to 100%

https://imgur.com/t8Ra3jD