Photovoltaic Resistive Cost Effective

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izentrop
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Re: Photovoltaic Resistive Cost Effective




by izentrop » 12/03/18, 09:32

We find MPPT 20 A unless 7 roro, and 30 A less than 10, I wonder if there is no deception on the denomination.

There is talk of fake MPPT here, but I do not understand spoken English?
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Re: Photovoltaic Resistive Cost Effective




by Ahmed » 12/03/18, 10:40

You click on the left icon on the bottom right (symbolizing a text) and you have the faithful transcription * of the lyrics: it is a very interesting option.

* This is not a more than approximate translation, but an automatic voice recognition system; of course, there are some little hiccups with close words and also according to the pronunciation of the author of the videos, but it remains very, very readable and it is even fun to note the mistakes ...
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Re: Photovoltaic Resistive Cost Effective




by chatelot16 » 12/03/18, 14:02

10 000 μF and 7A a 1 khz makes a ripple a little lower than 1 V at the panel terminal

it is possible to increase the frequency to decrease the capacitor, but it is not a good way: it increases the losses in the transistor if the command is not fast enough

it is believed that a mos can be controlled with a low current, but we must be wary of the capacity grid drain which makes the miller effect ... and requires a sufficient control current for a fast switching
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Re: Photovoltaic Resistive Cost Effective




by lilian07 » 12/03/18, 14:15

It's nice to see that a subject is moving forward with active consultation of its experts.
Like what there is still a space of simplicity in this world.
It would be necessary to be able to validate its calculations by a passage to the act ... for that there is Pvresistif
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Re: Photovoltaic Resistive Cost Effective




by izentrop » 12/03/18, 14:49

Thank you Ahmed, but it's still incomprehensible and I found the answer, it's only PWM.
The notice reflects this http://diyprojects.eu/wp-content/upload ... manual.pdf and dismounted we do not see the indispensable self to the MPPT http://diyprojects.eu/cmtp02-disassembl ... ontroller/ A true MPPT it is necessary to count 100 eur with a margin of safety for a panel of 300 W
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Re: Photovoltaic Resistive Cost Effective




by chatelot16 » 12/03/18, 15:06

this kind of solar regulator is the worst PWM: a PWM without a choke or capacitor that only reduces the charging current when the battery is full

this kind of controller fails to provide the battery with a current per pulse, not at all favorable to the life of the battery

we could make a better PWM without MPPT with capacitor and self: even without MPPT a PWM could adapt the rated voltage of the panel to the nominal voltage of the battery ... but it would be necessary to make a setting to be made by the user according to the number panel cell

the big advantage of the MPPT is to adjust itself as long as the panel voltage is within the possible range
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Re: Photovoltaic Resistive Cost effective with diode




by PVresistif » 20/03/18, 13:03

Hello
to improve the recovery I think of an assembly with two resistors in parallel including 1 with a power diode that blocks below a threshold voltage such as 25 V; this would give the following operation:
- below 25V: only the resistance of 6 Ohm works, above both (6 and 14 ohm is 4.2 ohm) work and we return to the original diagram; I can easily wire two son on steatite but cons for the diode j have the following questions:
- or find a diode blocked below 25 V (and who will support maxi 32 V 2.5 A)?
- can we specify the blocking voltage? or must choose from a catalog
- what cost?
- Will it work or is there a wolf? I have no knowledge about electrotechnical power
attached the project with diode
thank you for your enlightened comments
Attachments
curve with diode.pdf
(139.53 KB) Downloaded times 554
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Re: Photovoltaic Resistive Cost Effective




by izentrop » 20/03/18, 14:57

Hello,
There are the zener diodes. They are not made to withstand a large current and can not be found above 20 V, it is necessary to pass a power transistor for switching.
A trigger circuit is also needed to avoid oscillation around the switching voltage.
We can do all this in analog, but it takes more components and less flexibility than a microcontroller.
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Re: Photovoltaic Resistive Cost Effective




by chatelot16 » 20/03/18, 18:36

a zener diode is useless to control a resistance ... what would be necessary is to replace the resistance by zener diodes

a zener diode heats as well as a resistor and has a constant voltage better adapted to a photovoltaic than a simple resistance

problem is too expensive ... other problem semiconductors do not support high temperatures ... if the goal is to heat water it would require a very good thermal contact between silicon and water, and not aproximative thermal contact as in steatite water heaters or red water heater resistance to make water less than 100 °

there is no need to wiggle the c .. to c ... right it takes an electronic regulator specially adapted to optimize the use of a photovoltaic by ordinary resistance
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Re: Photovoltaic Resistive Cost Effective




by izentrop » 21/03/18, 10:48

To bring the steatite resistance closer to the optimal resistance which varies from about 11 Ohm to 3.8 Ohm between 100 and 250 W, a trick not complicated and cheap to do is a switching of resistors with N type Mosftet.
2 voltage threshold is established on an analog input.
For example: if the voltage increases above 32 V, the resistance of a bearing is reduced and if it falls below 25 V one goes up a step.
All this can be programmed step by step with a microcontroller more loosely than discrete components.

When a sufficient positive voltage is sent to the input of a mosfet N, it behaves like a short circuit at the output.
Below 6 Ohms the resistors are in parallel to distribute the higher current.
Connections to the steatite resistance can be done with high temperature sheathed wire and dominoes without the plastic.

The order of the bearings:

switched input - resistance in Ohms
none - 11
1 - 8
2 - 6
3 - 5.2
4 - 4.4
4 + 1 - 4
3 + 2 - 3.75
4 + 2 - 3.4
Attachments
CommutResistances.gif
Schematic diagram
CommutResistances.gif (5.42 Kio) Viewed 9115 times
prod-PV 250 W.gif
prod-PV 250 W.gif (90.21 KB) Viewed 9115 times
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