I doubt that you'll get enough energy to run a pump which
is as powerful as you want without spending more than
you figured.

But here's some figures.

A 15 watt panel costs about $50. Typically they come as
'12' volt meaning they're made to charge 12 volt batteries.

However they put out 15 volts (About) in full sun. And will
put out about 1 amp. In real life meaning less than
perfect conditions you can expect to run a motor which
requires 10 watts to it's full potential.

But you'll need a motor that is a voltage requirement of
12 volts to 15 volts. And to compound the electronics
part of the problem.. only a certain pump and panel
combination will get the most out of the 2 sq meters (about) that your panel covers. Get a motor that needs
slightly higher voltage and the panel won't match well
enough to give full performance.

Ask around and learn what you can. It's not all that hard
make the pump spin. But when you get to where you're
expecting certain results that's when the problems will
begin to show up as lack of performance.

Now that I've scared you a bit. What about the mounting
for the panel? It's glass with metal frame. You must put it
into another frame to keep it safe. ie you can't just screw
into the panel's frame or the glass might crack.

Battery backup? You could help the situation if you used
a battery in that the battery would suck up all of the power
the panel had available and the battery would also 'fix'
the voltage to about 13.4 volts. Get a pump for 13.4 volts
and your match will be better than a panel and pump only.
But you've added some cost. You don't need any
electronics between the panel and battery (if you use a car
type lead / acid battery) but if you use NiMH or especially
Lithium you must have some electronics to regulate the
current and voltage.

Let's put it this way. If you can find what you want already
as a product for the price you want to pay except that it's
30% higher than you expected.. You probably can't
do any better than that unless:

A. You have a background in electronics and know what
kind of products , pumps/panels/voltage converters are
available off the shelf. That usually requires someone
working in the field daily.

B1. You have a friend who's done it and will help you.
B2. You have a reputable site which tells you what to buy
and tells you how well it worked.

I wish you luck. If you want to mention how much water
per minute / hour / day you want to move and how high
it has to spray and if it's moving something with the water
pressure .. mention what itis and how much it weighs and
how far it has to move.. I can look back in a week and give
you more accurate power requirements.

Andre

thanks for such a detailed explanation

I went to local garden store that advertises itself as "natural" so thought it would have better quality solar pumps but they had none--just conventional electric and they had posted the cost to operate pump based on the KWH of .15--

thinking we would get a pot that is about 3 ft high--
and would not want powerful spray--more like a bubbler--
not sure exactly what power for the pump
but remember thinking from the flow rates on the pumps there it would cost maybe 125 a yr -- which is not that bad--we probably would not pump at times during the winter..and could put timer on it to stop at night...

it is not so much the cost but the fact that the closest electric connection is on the porch and would mean either running the cord across the porch's floor which would be trip hazard or running the cord up the wall/across the roof--and this porch has a high roof--maybe 20 ft--so that would be difficult and just ugly IMO

guess I need to check for exterior electric outlet that might be on outside wall --but don't think there really is one beside the porch's

what do you think would be the best solution if that porch extension is the only one available--

this link is to solar pump that has 18 v -- and it seems to be more powerful lift factor than we probably need so we would be paying more than we would need...

but it would cost less than 2 yrs of electricity

Here is a link that might be useful: fountain pump site