I’m working on a small project where I can connect low voltage/watts equipment using an inverter connected directly to my solar panels. I know you can connect them directly to each other but what is the power ratio to run the inverter and its load….meaning. If i want to run a 100 watt 12V inverter, what solar panel(wattage/amps/voltage) do i need. How much amps/voltage do i need from the solar panels to make the inverter work, with and without load?
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3 Comments
Rob T
on 6th Jul, 10 07:07pm
If it’s a 12V inverter, the voltage required is, er, 12V. If you try to run it from a lower voltage it might not work at all, or you might get the wrong output voltage.
The inverter data sheet should tell you what current is needed for maximum output. You can get a rough idea from watts = volts x amps. So for a 12 volt supply, 100 watts needs 100/12 = 8.3 amps. Actually it will need a bit more, because inverters are not 100% efficient. A good one should be about 90% efficient at maximum load, so the current required would be about 8.3 / 0.9 = 9.2 amps.
The efficiency at low loads is worse, it might be as low as 50%. So if you only needed 12 watts (for a low power light or whatever) the theoretical current required would be 1 amp but in practice you might need 2 amps.
Ricky
on 6th Jul, 10 07:07pm
Normally it is not connected directly because the voltage and current output from the panel is fluctuating as it is entirely dependent on the sun’s rays.
So the solar panel is therefore connected via a “Charge Controller” to a 12V lead acid battery to charge it.
The battery is then connected to the inverter.
SolarBerg
on 6th Jul, 10 07:07pm
The other two answers are pretty accurate. With the expense of charge controllers, batteries, inverters tho, you may consider simply buying a different device that can take DC power. If you can match the device to the panel you wont need any of the intervening equipment. Many retailers sell high-efficiency DC lights, pumps, etc just for solar apps. What are you trying to power?