Solar panel sizing it will be charging a car battery.
 

My jet ski air lift uses a whole house vacuum to blow air in to lift it up.
http://ecorenovator.org/forum/billia...-pwc-lift.html

It is working great but I don’t think I want to wire my dock with power. Our lake is a hydro power lake so the dock follows the water as it gets lower and mover it back in as the water rises.

http://ecorenovator.org/forum/attach...1&d=1468948381

The vacuum uses 750 watts at startup then 629 watts running. It runs about 2 min. a busy day maybe four cycles for a total run time maybe 8 min. This is usually just two days of this maybe 3 days.
I bought a HF 750 watt inverter with a two year warranty. I did a test with my pontoon boat battery.
It was able to run the blower with this setup.

I have a 7 watt solar panel do you think that is enough to replenish the battery? It will have five days to do it.
Amorphous Solar Panel — 7 Watts | Amorphous Solar Panels| Northern Tool + Equipment

Using a round fudge factor number of 650W, at 8 min per day(0.13hours) gives 84.5 Whr usage per day. For two days about 169 Whrs. If the panel gives a full 7 Watts at maybe 90% efficiency(including charging the battery) and you average 5 hours of usable sun per day. Then 6.3 watts times 5 hrs returns 31.5 whrs per day or 157.5 for 5 days. This number doesn't include any charging time on the days that the blower is being used nor does it include any days where it is too cloudy to have useful full sun. Also charging a battery is normally less than 90% efficient but I gave you the benefit of the doubt.
Summer time probably gives a few more hours of good sun per day on average too but cloud cover can easily offset the extra sun time. I think I'd bump it up a bit to at least a 10 or 12 watt output.
JJ

Pinball,

I started with a 10 W panel to keep a deep cycle lead acid battery charged - and it was not enough. So I bought another cheapie 20W off Ebay and connected them in parallel.

Power used for 12 V DC pond aerator connected to a timer.

That works great!

Steve

Did you have to use a charge controller?

7 watts?
No.

Pinball,

Yes, I do use a small 10 A charge controller. I think $8 on Ebay.


Steve

Thanks guys I ordered a 20 watt solar panel off ebay and a cheap 10a charge controller.
53.38 shipped. Now I will just need to find a deep cycle battery. Then find stuff to mount it all to my dock.
http://ecorenovator.org/forum/attach...1&d=1469060929

http://ecorenovator.org/forum/attach...1&d=1469061043

The 7 watt panel I had I usually just use those to keep a float charge and keep on equipment that just sits. Like my boat.
I will have to build a mount for the solar panel so I just bought the one that should work for this setup.