sun power use

[hans]

Hello all,
I don't want to reinvent the wheel.

 Until now I have always used 5 volts supply voltage, but because of a solar panel I would like to work on 3 volts. Which processors should I use and what should I pay attention to?
Thank you in advance,
greetings Hans

[vsurducan]

You may continue to use it at 5V if the energy extracted from the PV is drawn via a MPPT ( maximum power point tracking) IC and your solar panel assures the current needed for your electronics. Many panels have 6V open at 0.3A or 0.5A short circuit current

Actually any actual PICmicro will run on 3.3V ( including those rated for 5V) if the internal oscillator is set to maximum frequency intended only for 3.3V. Most of the low power PICs ( LF series) will run down to 2.2V ( some down to 1.8V) so you may connect the solar panel directly on your LDO without MPPT or PWM.

best wishes

--
You received this message because you are subscribed to the Google Groups "jallib" group.
To unsubscribe from this group and stop receiving emails from it, send an email to jallib+un...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/3220a563-f63f-435b-b0a6-c088cc777aaen%40googlegroups.com.

[Rob CJ]

Hi Hans,

Most PICs can operate at 3 Volt, below a screenshot from the datasheet. I only use F versions.

Just check the datasheet for the PICs that you have. 

I have done several projects using a PIC that is supplied by batteries so operating at 3 Volt or lower.

What I do not know for sure if when you program the PIC if it should be at 5 Volt, maybe only if you use Low Voltage Programming, so I  normally program the PIC when it is connected to a 5 Volt power supply but in the application it can run even on a supply voltage as low as 2 Volt.

If you have peripherals that work at 5 Volt you could always use a step-up converter to step-up the power supply from 3 Volt to 5 Volt.

Kind regards,

Rob

---

Van: jal...@googlegroups.com <jal...@googlegroups.com> namens vsurducan <vsur...@gmail.com>
Verzonden: woensdag 29 juni 2022 09:11
Aan: jal...@googlegroups.com <jal...@googlegroups.com>
Onderwerp: Re: [jallib] sun power use

 

To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/CAM%2Bj4quz-mvFLM7nuWmPg0YBcQCGNLDqw09bJMr%3DbKpmALa9TQ%40mail.gmail.com.

[hans]

Such a prompt response! I bought a solar charger with a built-in 5000mAh battery. It delivers a beautiful 5 Volt but with a minimum load of 150 mA. Opened the case and the lipo delivers 3.5 Volts. So I soldered a few more wires to it. Hence my question. It's still so much fun.

Now i have to discover what a  MPPT is.

regards

Hans

Op woensdag 29 juni 2022 om 09:59:30 UTC+2 schreef rob...@hotmail.com:

[Rob CJ]

Hi Hans,

Don't make it more complex than it is. An MPPT (Maximum Power Point Tracking) is used on solar panels to get the most out of it but you do not have to add such a device.

If I am right a Lipo battery needs a certain way of charging and so you need a special Lipo battery charger.

I made a Cat repellent some time ago using a small solar panel. And since I am using three NiMh batteries (so 3.6 Volt) I use a small charging current for keeping the batteries charged. The batteries are connected to the solar panel only via a diode (Shottkey in this case because it has a low voltage drop).

For your info. You can find the schematic diagram here: https://www.instructables.com/Cat-Repellent/

Kind regards,

Rob

---

Van: jal...@googlegroups.com <jal...@googlegroups.com> namens hans <hanz...@zeelandnet.nl>
Verzonden: woensdag 29 juni 2022 11:22
Aan: jallib <jal...@googlegroups.com>

To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/b59b60f5-848e-4d33-b9d9-a6bc2b872dabn%40googlegroups.com.

[hans]

Hi Rob,
The set has both a solar panel and a lipo battery, so I don't have to worry about charging. I'm just curious if the solar panel can keep up with the consumption. I can also charge it via USB.
By the way very nice to see a project, most of the contributions are very abstract.

Kind regards

Hans

Op woensdag 29 juni 2022 om 11:44:28 UTC+2 schreef rob...@hotmail.com:

[vsurducan]

It depends, Rob. With a MPPT you may use a smaller PV surface, older technology, cheapest, with much better efficiency in the morning and in the evening when there is only light and no direct sun. I'm very sensitive to this because I've just finished my 2Kw real solar supply for the house and this is crystal clear...(at least for me). :)

For Hans: A MPPT is a circuit which continuously measures both the voltage and the current drawn from the PV. At each moment when light varies there are a few pairs of voltage/current at the PV output which produces maximum energy. These can be seen on the PV output characteristics and heavily depends on load and amount of sunlight.  If you do not use the best pair, you may lose as much as 20% to 30% of what PV can offer.

On the other hand, when the PV goes hot, it decreases its output energy with an usual rate of 0.3% to 0.4% per each celsius degree above 25C. In summer, a PV can easily reach 60-70C. The best monocrystalline PV technology has today a power decrease around 0.27%/C

Of course if your load is 0.3W ( 3V/100mA) then it does not count too much, only if your PV cell delivers enough power.

I hope this clarifies your questions about if worth or not.

best wishes,

To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/GVXP195MB1637E6A59B7619F80BB4F423E6BB9%40GVXP195MB1637.EURP195.PROD.OUTLOOK.COM.

[vsurducan]

Such solar kits usually have PWM charging, they need PV voltage higher than the battery voltage.

To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/16197ba2-f8db-441f-865b-3acd184f4d7en%40googlegroups.com.

[Oliver Seitz]

Hi Hans,

it's true, you don't need to worry about charging, but you do need to worry about stopping discharging. LiPos may explode if overcharged or over-discharged. The device you've bought has both- charge and discharge controller. But, with your extra wires, you're discharging the LiPo directly without the discharge controller. That is ok, if you're really sure the LiPo will never go empty. If you're not so sure about that, you would need a way to stop discharging at a certain voltage, like 2.6V. Really switching electronics off to only keep drawing few nanoamperes is possible, but not always easy.

Greets,

Kiste

Am Mittwoch, 29. Juni 2022, 12:34:35 MESZ hat hans <hanz...@zeelandnet.nl> Folgendes geschrieben:

https://groups.google.com/d/msgid/jallib/16197ba2-f8db-441f-865b-3acd184f4d7en%40googlegroups.com

.

[vsurducan]

About keeping up with consumption, PV has to (i) charge the battery and (ii) supply your board.

If you really want to try something new, then a two axis tracking system will improve your charging by about 40% with the same PV.

Why? Because the PV will stay oriented to the sun, except for minor clouds and heavy rain when everything will be disintegrated :)

https://www.banggood.com/Smart-Solar-Tracking-Equipment-Maker-Project-DIY-Kit-Technology-for-Arduino-p-1952195.html

To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/366793553.5677601.1656509982227%40mail.yahoo.com.

[hans]

Hello
  Kiste
I still have to come up with something to switch off in time due to too low voltage, but you did wake me up. Thank you.
Vasile
Years ago I had a larger solar panel rotate with the sun. I did the incline manually. However, the rotating construction must be very heavy and in a big storm I was only just able to save the case
Near us there is a park with 12 such panels, it was always surprising that they are never all in the right direction. A technician in this field told me that the added value in yield is almost lost at the cost price of the installation and that they now just use fixed panels.
And nevertheless it is very nice to be working on this. The application of the MPPT is again its news for me.
thanks everyone
regards
Hans

Op woensdag 29 juni 2022 om 16:22:16 UTC+2 schreef vasile:

[hans]

Hello all,

Here is the solar panel I will be using. I just went back to 12 volts and a small lead acid battery. One motor drives the axis that is parallel to the Earth's axis and follows the sun. Actually the screen should go 24 degrees up (June) and 24 degrees down (December) but I did some measurements and the gain is too small for me to do anything about it.

Anyway, Jal lets things run smoothly again and now we just have to wait and see if the weather gods accept this thing.

regards

Hans

Op woensdag 29 juni 2022 om 17:28:57 UTC+2 schreef hans:

[vsurducan]

Super! :) cool.

Maybe expand this stuff to a 1Kw system and two axes?  Then you will face many other issues like the voltage/current measuring errors existing in ALL chinese MPPT devices? 

best wishes,

To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/675be8f1-9300-4934-8467-1466f4faf675n%40googlegroups.com.

[Rob CJ]

Very nice Hans and good to see that it works.

You should start a solar farm 🙂

Kind regards,

Rob

---

Van: jal...@googlegroups.com <jal...@googlegroups.com> namens hans <hanz...@zeelandnet.nl>

Verzonden: zaterdag 9 juli 2022 17:35

To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/675be8f1-9300-4934-8467-1466f4faf675n%40googlegroups.com.

[hans]

Hi Vasille,
I completely agree with you that a control on two axes and an MPPT charger for the battery is the best, but the question is how much investment it entails compared to the yield. Here's a picture of the park near us where the panels have had irregular positions for years. Even this “professional” approach makes me raise my eyebrows. All in all, it's still fun and educational.
regards
Hans

Op zondag 10 juli 2022 om 09:43:45 UTC+2 schreef rob...@hotmail.com:

[hans]

Hi Rob,
My shadows are getting longer, but the sun is still shining.
regards
Hans

Op zondag 10 juli 2022 om 09:43:45 UTC+2 schreef rob...@hotmail.com:

Very nice Hans and good to see that it works.

[vsurducan]

:) :P

These have Chinese controllers for sure!

The time investment is equal to the know-how you will acquire, so it is invaluable.

The simplest way to do it is in a pure analog way, using a four quadrant analog detector with LDR of photodes. This is simple, being simple it works, the only issue you will have is to keep it dry. You still need a microcontroller to drive the motors at defined moments of time ( to avoid useless power consumption all the time) and to "park" easily your tracker on heavy rain and storms.

The most complex way is to do it in a pure digital way, input is the GPS coordinate, computing the sun trajectory for that coordinate and add a correction table for each day of the month. Such a device already made (EU product) is about 300 euro, I would say is not expensive for your capitalist world. :)

best wishes

BTW, after you tracker works you may propose to the owners of the neighborhood park to make them work too. :)

To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/dc051144-9ba0-414f-9009-e87515fdbe40n%40googlegroups.com.

[hans]

Hi Vasile,
Isn't something like this a challenge for the JAL world, isn't it much more fun to build yourself than to buy?
regards
Hans

Op zondag 10 juli 2022 om 11:26:02 UTC+2 schreef vasile:

[vsurducan]

Hans, yep, it's more fun. But you will not be able to reach the professionalism level of a product which has 10 years of experience behind.

Everything is ok until you have to climb on a roof of 8m height, in the winter, just because you've missed something on your design...

Hobby is fine, but there are some levels with other requirements.

best wishes,

To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/4496f499-5639-4934-b5a7-58abdc79126bn%40googlegroups.com.

[vsurducan]

Hans,

if you want a long life for the acid gel (VRLA hopefully, beter lead-carbon but I doubt you bought that one) you need to discharge it at max 50% ( better only to 80%) of it's maximum capacity. Deep discharge is the accumulator dead no matter the lies written on battery datasheet datasheet ( 800 cycles and deep discharge).

Also check carefully the floating voltage ( near zero consumption) to not exceed 13.3-13.6V.

Lead-acid gel has the ugly behaviour of slow voltage decrease during gel drying. At the same time the current decreases too. Serious charge-discharge cycles are better than float discharge.

Be happy. You have now sun power for the puppets!

On Wed, Jul 13, 2022 at 3:15 AM hans <hanz...@zeelandnet.nl> wrote:

Hello all,

Here is the solar panel I will be using. I just went back to 12 volts and a small lead acid battery.

 One motor drives the axis that is parallel to the Earth's axis and follows the sun. Actually the screen should go 24 degrees up (June) and 24 degrees down (December) but I did some measurements and the gain is too small for me to do anything about it.

Anyway, Jal lets things run smoothly again and now we just have to wait and see if the weather gods accept this thing.

regards

Hans

--

You received this message because you are subscribed to the Google Groups "jallib" group.
To unsubscribe from this group and stop receiving emails from it, send an email to jallib+un...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/jallib/1daba767-6631-47b2-aca7-8272c214a92bn%40googlegroups.com.

[hans]

Hi Vasile,

I already took your warning. The little black box on the left is an old regulator that both monitors the max voltage and shuts down when the battery is dead.

Op woensdag 13 juli 2022 om 05:00:41 UTC+2 schreef vasile: