PV Gap

Jerry Said:

I need to connect a solar panel to a 400watt Inverter. What size, watt, amp solar panel do i need?

We Answered:

A panel labeled as 12V, 150mA has a practical output of 1 watt, so probably far less than needed to even start up your inverter. I'm guessing that the inverter is the type that normally plugs into a car? Those are not especially efficient, because they know the car's battery can supply ample current, and they want to be low-cost.

What you could do is charge a car battery over a period of weeks with your panel, then connect the inverter to the car battery.

Another experiment, if you can get an ammeter, is to measure how much the inverter is drawing from the car battery when you have your desired device plugged into it. That will tell you what current you need from your solar panel.

My wild guess is that you would want at least 80 to 100 watts of panel, unless you wanted to power something that's several hundred watts, in which case, you would buy a panel (say) 40% bigger than your load. This is because the cheap inverter will waste a lot of energy as heat.

Donna Said:

Can a solar panel work with an inverter?

We Answered:

Solar panels output a very small amount of current. Even though you're getting 12V from the panels, you aren't getting enough amperage to power even the inverter itself, let alone anything plugged into the inverter.

Car batteries are able to be used with inverters because they can crank out enough amps to power the inverter and whatever is plugged into it. Inverters only step up voltages and change DC to AC. They do not increase power (wattage) potential. If you want to plug in a 20W appliance into the inverter, the 12V source must be able to deliver 20W of power regardless of voltage.

In pretty much everything solar powered, the panels are used in conjunction with batteries. The solar panels slowly recharge the batteries. The batteries are where most of the power comes from. Nothing is driven directly from the solar panels themselves unless the power requirement is low enough, such as a calculator.

Solar panels will have an output rating in watts (W). If the wattage of your inverter plus whatever you plug into it is lower than the panel's output rating, then it can power it directly, provided you have 100% light input into the panel.

Oscar Said:

What size power inverter can a 80w solar panel supply power to.?

We Answered:

The 80 watts is what the panel can provide at any instant. If over a period of time it supplied enough power to charge a storage battery to over 1200 watts then the answer is yes. By itself the answer is always no.

That charging will take 15 hours to give 1200 watt hours to the battery. And of course if you pull out the 1200 watt hours from the battery using the inverter then you will need more recharging, so in the long run you can only put about an 80 watt load onto the inverter.