Hello Living in Florida = HOT SUN!!



I am a newbie to this forum, I have basic understanding of electronics and get terms like MOSFET, PNP, 5V rectifiers etc etc..

I would like to make a simple 12 DC ceiling fan using a 75w(+-) Solar Panel.

The tricky part, when the fan is switched ON, I want to maintain 75w from THE SUN or a DC power supply. My goal here is to when the sun CAN power the fan it does, but it's offset by the home AC=>DC Power adapter to maintain 75w..

A push in the right direction WOULD BE AWESOME!!

**an idea maybe to add some output to show the percentage of SUN POWER .vs HOUSE POWER.

 

I have a 6" 120V 0.17A (20W) fan that cools me off quite well (on low speed). I think a 75W solar panel will be able to run a fan and charge a battery so you would rarely need to use AC power.

 

The simplest possible solution is just a blocking diode to prevent current from flowing from the battery to the PV panel. Then the fan connects to the battery as normal.

The problem with this solution is that there is a risk of over-charging the battery, especially if the PV panel is "large" and the battery is "small". To prevent this, there are battery charger ICs designed for every battery chemistry. There are also simple, less featured solutions such as constant voltage for lead-acid, low constant current for Nicad and so on.

Oops, I missed the bit about the AC adapter.