Solar Inverters are around 94 to 96 percent efficient when supplying power and converting DC power to AC.
There's a slight loss of power due to the wiring from the battery to the Inverter but if you use a proper and large enough wire from the battery to the inverter then there should not be much loss of power.
However a slight voltage drop from the battery to the inverter is normal.
The solar panels keep power supplied to the batteries so they stay charged while you are using electricity.
The only maintenance that a solar panel or solar panels need is removal of snow, dirt etc from the solar panels and sometimes wiping the solar panels down if they get too dirty.
Also maintaining the solar panel batteries and replacing the solar panel batteries when needed every 5 to 10 years or so is about all the solar panels need for maintenance.
Most Solar Panels will last 25 years without any issue.
You can get free solar panels through some rebates and incentives.
But you must sign an agreement and agree to there rules etc.
I've heard that getting solar panels for free through your county, city or Utility or other program can be a bad idea.
You have to stick to there rules and regulations and you may also have to pay a tax on the free solar panels in some cases which makes them not so free after all.
I would recommend just buying your own solar panels and batteries and inverters if you really want solar panels.
They can be costly but it's worth it to own the solar panels outright and they can save you some money on your utility bills after a year or two of owning and installing them.
There's also the peace of mind that you will have power when there's a power outage when you have solar panels.
That alone is worth the cost of the solar panels.
Solar Panels do work still when it's cloudy out.
Although when it's cloudy outside and the sun is not shining enough the solar panels may charge the batteries a bit slower than the would if it were sunny out.
Solar Panels work best when it's sunny outside and you get more power and charge from sunny days than you do on cloudy days.
But even when it's cloudy outside your solar panels will work to charge your solar panel batteries and provide you with some power.
Solar Panels will work with either direct or indirect sunlight to generate power.
Solar Panels are most effective when you have direct sunlight but they also are still pretty effective when the light is reflected or partially blocked by clouds.