Use a capacitor to supply the peak current during the transient period. That's what they;re used for even on motor drivers with mains or battery sources. But make note about whether the wattage (and hence current rating) of your solar panels are for peak conditiosn and so your motor may still not operate unless in direct, full sunlight.

It seems like a fairly heavy continuous load to run off of solar panels though...

Hiya Amitraj,
A good unit to use to drive pumps, motors etc directly off a solar panel is a device called a maxi-maximizer. I did notice in a renew magazine they sell a kit for them or you could try and find the schematic on the net.

Here is link to the mini-maximiser and by simply upgrading some of the parts should give you the required current draw.
http://www.voltscommissar.net/minimax/minimax.htm

Cheers Bryan

Originally Posted by amitraj

Hello,

Bryan - thanks for this effort!

I am not sure if this maxi-minimiser is available in India (of course I can import that).

I will too check out.

Thank you.

Amitraj

Just build it yourself using verboard. Page 2 of that website gives you all the details. To beef it up for more amps put some bigger fets and caps on and a few other tweaks

Cheers Bryan

I'm not sure that Maximizer makes any sense at all. PWM'ing the stalled motor will only lower the current which will not assist in starting it AFAIK.

Starting the motor with a capacitor may require a very large capacitor. It is difficult to say what is required since it depends on the inertia of the rotor and many other factors. Let's say it's very fast and requires 16 amps for only 0.2 sec, and the solar panel produces 7 amps out of that so we only need 9 amps from the cap. But if the capacitor voltage drops below 8v before 0.2 sec then the motor will not start.

I get 0.45 Farads for that hypothetical spec. There are stereo system "boost" capacitors readily available in that range in the US, but elsewhere finding that much capacitance in this range may be difficult.

It would make more sense to install a battery on your solar panel. Not only does this solve your starting problem but you can better utilize your panel. For example there are going to be many hours where the panel produces electricity but it is too little current to run the pump so it is useless. If you charge a battery for 1 hour in weak sun you can run the pump off the battery+panel for 30 min you get output you otherwise could not use.

I agree, I don't see how PMing a motor can help start a motor, if anything, it'll only make it worse.

For the capacitor idea to work, you need to give the capacitor time to charge before the motor is switched on.

That maximiser circuit is sold over here in Oz as a kit and it's been around for donkeys ages AND WORKS. although I haven't made on as yet as I haven't had the need I do know many people who use it on a daily basis including several people who I put them onto it. The circuit is designed for the public domain by a guy from selectronic ( the mob who make sinewave inverters). As Amitraj has stated his need is for drip irrigation and this circuit would be perfect for the application.

Below is the link to buy the mini-maximiser kit from ATA.
http://shop.ata.org.au/cart.php?targ...ategory_id=251

Cheers Bryan