how to read watts ?

[jackal]

I'm certain it has been asked before and I appologise for that but I not sure on how to read the potential production from my wind turbines and pv. Any advise appreciated.

j

[EccentricAnomaly]

Sorry, haven't a clue what you're asking about. Are you asking about how to get estimates of likely production or what such estimates mean or something else?

[dimengineer]

I'm certain it has been asked before and I appologise for that but I not sure on how to read the potential production from my wind turbines and pv. Any advise appreciated.

j

My PV inverter has a display. It displays instantaneous Watt, kWh today, and kWh total.
So look at your inverter 

[martin]

Sounds like you're starting from scratch, and you don't have an inverter with a display.......... Very roughly, your pv panel should be marked as being a number of watts - if it were 50 watts, then in bright sun, it should produce that wattage when (for instance) fed into a battery - most small wind turbines are marked as being of a number of watts, usually at a particular windspeed - (something like 500 watts at 8 metres per second)

[jackal]

Sounds like you're starting from scratch, and you don't have an inverter with a display.......... Very roughly, your pv panel should be marked as being a number of watts - if it were 50 watts, then in bright sun, it should produce that wattage when (for instance) fed into a battery - most small wind turbines are marked as being of a number of watts, usually at a particular windspeed - (something like 500 watts at 8 metres per second)

My inverter  only has leads and volts no measure of wattage. I  was wondering if there was a way I could measure the watts supplied by the turbines with a multimeter. I am DIY building my turbines  also the two navitron turbines I have are obvious chinese inports and the information is poor. I think they were 350 watt but I have my doubts so would like to measure the outputs.

Thank

j

[martin]

You'll need to take 2 measurements and multiply them  -you should never let a wind turbine run unless connected to a load of some sort, so you'll need a battery/ies of the correct nominal voltage to connect it to - just measure the voltage "across" the battery while it's trundling, and then measure the amperage, and multiply the two together.... (bearing in mind that in the case of the original small Navitron turbines they can produce considerably more than their rated wattage)

[Eleanor]

Assuming that the outputs are DC you can use a DC clamp meter and clamp it around the cable from the turbine to measure amps and volts and use these values to calculate watts. Useful for measuring at various points in a system but not cheap. We have this one :

http://uk.rs-online.com/web/p/clampmeters/6973967/

[EccentricAnomaly]

There are cheaper solutions than a DC current clamp.

The "proper" version has a small shunt resistor which which drops a few millivolts at the required currents so you can measure the current using a multimeter on the 200 mV range, or whatever.

If you're like Outtasight, of this forum, then you don't bother with a specific shunt but just stick pins in the cables you're using to carry the current around anyway. He linked to a description of how he does this on the Mr Sharkey site in his first post on this monster thread: https://www.navitron.org.uk/forum/index.php/topic,8368.0.html but unfortunately that's giving a 403 Forbidden error to me now.

Not knowing the resistance you have to calibrate it. That's probably best done by drawing a bit less than 10 amps measured with a normal multimeter on the 10 A range and, at the same time, measuring the voltage with another meter. Since the voltage is proportional to the current you can then use the setup (once you've removed the current measuring meter) to measure bigger currents.