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, On Wed, Jun 29, 2022 at 12:44 PM Rob CJ <[email protected]> wrote: > 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:* [email protected] <[email protected]> namens hans < > [email protected]> > *Verzonden:* woensdag 29 juni 2022 11:22 > *Aan:* jallib <[email protected]> > *Onderwerp:* Re: [jallib] sun power use > > 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 [email protected]: > > 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:* [email protected] <[email protected]> namens vsurducan > <[email protected]> > *Verzonden:* woensdag 29 juni 2022 09:11 > *Aan:* [email protected] <[email protected]> > *Onderwerp:* Re: [jallib] sun power use > > 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 > > On Wed, Jun 29, 2022 at 9:57 AM hans <[email protected]> wrote: > > 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 > > -- > 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 [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/jallib/3220a563-f63f-435b-b0a6-c088cc777aaen%40googlegroups.com > <https://groups.google.com/d/msgid/jallib/3220a563-f63f-435b-b0a6-c088cc777aaen%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > -- > 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 [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/jallib/CAM%2Bj4quz-mvFLM7nuWmPg0YBcQCGNLDqw09bJMr%3DbKpmALa9TQ%40mail.gmail.com > <https://groups.google.com/d/msgid/jallib/CAM%2Bj4quz-mvFLM7nuWmPg0YBcQCGNLDqw09bJMr%3DbKpmALa9TQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > -- > 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 [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/jallib/b59b60f5-848e-4d33-b9d9-a6bc2b872dabn%40googlegroups.com > <https://groups.google.com/d/msgid/jallib/b59b60f5-848e-4d33-b9d9-a6bc2b872dabn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > -- > 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 [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/jallib/GVXP195MB1637E6A59B7619F80BB4F423E6BB9%40GVXP195MB1637.EURP195.PROD.OUTLOOK.COM > <https://groups.google.com/d/msgid/jallib/GVXP195MB1637E6A59B7619F80BB4F423E6BB9%40GVXP195MB1637.EURP195.PROD.OUTLOOK.COM?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "jallib" group. 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