• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Low current, high output voltage?

Status
Not open for further replies.

Nick'

New Member
Hi, i am working on solar energy. I have seen a solar energy cell generates about 10 micro ampere of current. We have this formula, V = Ir . Therefore I could produce a 9v worth of energy source. What i have to do is connect the energy source (10uA) to a 1 megaohm resistor. It will produce about 10V, which is what i want. Is this possible? If yes, i would like to implement it in such a way.
 

AllVol

New Member
Is this possible? If yes, i would like to implement it in such a way.
Solving for I*R doesn't produce a voltage, it merely determines the amount of potential necessary for that I to pass through that R.
 

Nick'

New Member
Impossible. You mean the formula is wrong? No way!!. My teacher taught me this since when I was in secondary school.
 

georgetwo

Member
ya that teacher really needs to go back to school.

the best way u can go about this is by adding other solar panels and connecting them in parallel because when they are connected in parallel, the current will be added together while the voltage remain almost constant.
 

dknguyen

Well-Known Member
Most Helpful Member
In theory that would be true for a perfect current source (one that can force a certain current through ANY resistance no matter how large. This is the same as saying the current source can produce an infinite voltage difference). In reality, there are limits. A solar cell, for example, might produce 10uA in short-circuit (at 0V) and produce 3V at open circuit (0A). Anything in between is less than 10uA and less than 3V.
 

Nick'

New Member
I dont get what you guys are saying. Come on, the formula is v=ir. where v is voltage, i is current and r is resistance. So, R is directly proportional to v. If R is increased, then V is also increased.
 
Last edited:

PatM

Member
I dont get what you guys are saying. Come on, the formula is v=ir. where v is voltage, i is current and r is resistance. So, R is directly proportional to v. If R is increased, then V is also increased.
Read post #2 again.
 

smanches

New Member
I dont get what you guys are saying. Come on, the formula is v=ir. where v is voltage, i is current and r is resistance. So, R is directly proportional to v. If R is increased, then V is also increased.
You are thinking about it backwards. What you solved is how much voltage the solar panel would have to produce to push 10uA through a 1MΩ
resistor.

Only active components produce power, which is the solar cell itself. The resistor is a passive component which can only dissipate power, not enhance it. If R is increased, then V MUST increase from the ACTIVE source to push the same current.
 

Nick'

New Member
MM.. Things tend to get obvious now. By the way, how can i increase the voltage to 10V? Can I use a transformer or something?
 

blueroomelectronics

Well-Known Member
What are you connecting that needs 10V? 10ma is not much current and that's probably only available in full sunlight at noon near the equator. What's the model of the panel you're using?
 

rmn_tech

Member
Sorry Blueroom but From what the OP was saying the "panel" is producing 10µA not 10mA

Nick If you are having difficulty think about it this way.

In your mind replace your panel with a 1.5v battery that can supply 10µA. OK

Now it does not matter what size resistor you connect in the circuit you can not have more than 1.5v

Basically what we are saying is that yes V=IR R=V/I I=V/R but in your case V is a constant. Change R and I will change but unless R is low or short circuit V remains constant. (Purists I know allow for light on the solar cell) but basically this is correct.
 
Last edited:

Nick'

New Member
I dont have a solar panel yet. I read online on how to make one. So, it produces about 10uA. Transformer cannot change the voltage too, can it? I want to change the voltage because i want to use it with my circuit which requires 10V.
 

tcmtech

Banned
Most Helpful Member
At ten millionths of an amp your not going to even have enough power to light up a high brightness LED even to a dim state.
Sorry but the ambient static electricity you generate when walking over carpet has more power available.
 

bountyhunter

Well-Known Member
Hi, i am working on solar energy. I have seen a solar energy cell generates about 10 micro ampere of current. We have this formula, V = Ir . Therefore I could produce a 9v worth of energy source. What i have to do is connect the energy source (10uA) to a 1 megaohm resistor. It will produce about 10V, which is what i want. Is this possible? If yes, i would like to implement it in such a way.
None of the terms in your paragraph refer to energy which is measured in Joules.
 

bountyhunter

Well-Known Member
Impossible. You mean the formula is wrong? No way!!. My teacher taught me this since when I was in secondary school.
Considering the fact you are mixing terms for electromotive force (volts) and current (Amps) and calling them energy, I think you need to go back and ask the teacher some questions about electricity.
 

Nick'

New Member
Ok. I am studying more now. I have a question. Lets say i have a 3v and 0.5A solar panel. How can i increase the voltage. Won't a transformer work for this? I know voltage is essential in maximising the efficiency of a device (motor). I don't want to increase the current as it will negatively affect the efficiency of the device (motor).
 

rmn_tech

Member
If you increase the the voltage then the current will decrease (you can't get anything for nothing).

You will also need to convert the DC from the panel to AC to work a transformer. this conversion will also use some of your power.

It would be simpler to run more panels in series to increase both voltage and current.

P.S. A device will only use the current it needs.

You really need to study more about Ohms Law.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top