# What size panel should I use on a Shurflo pump?



## Sparticle (Nov 1, 2004)

Hey everybody. We have a 2088, 3.6 gpm, 24 volts. I bought it for PV direct pumping but the site is too shady so we'll use a battery. Do the panels need to be wired 24 volt? How about the battery? Because of money, we'd like to use a dual purpose Marine battery for this. Will that battery do the trick until we can get something else? Thanks.


----------



## Sparticle (Nov 1, 2004)

I forgot to mention that we have 4 120 watt panels, 4 77 watts, 2 50 watts, and 4 40 watt panels. Thanks.


----------



## wy_white_wolf (Oct 14, 2004)

If the site is too shady to run solar direct it is too shady for solar to charge the battery.

Yes, everything will have to be configured to 24VDC unless you have a DC to DC convertor.

We would also need to know the number of hours you want to run the pump daily.


----------



## Sparticle (Nov 1, 2004)

It has some Sun, just not all day. I'd say it has 2-4 hours a day. Is that enough to charge a battery? We use that dual purpose battery for all kinds of things and would rather not buy another battery to run the water pump. Thanks very much for the help.

Don't need to run the pump much, 1-2 hours a day.


----------



## kbabin (Aug 1, 2006)

Sparticle,

I found this pdf for the pump you are talking about. And it listed the max amps at 24volts would be 2.5 (http://www.shurflo.com/files/RV-Pro...mps/Standard Pump - pds-2088-473-143_443_.pdf)

So, it sounds like you are going to be using about 120 watts a day if you run the pump for 2 hours. Please check my math...

Kev


----------



## wy_white_wolf (Oct 14, 2004)

So it sounds more like an issue of not having the sun available when you want to run the pump.

Basic calculations:

So you usage is 2 hours max a day with a 24V pump that draws 2.5 amps.

2H * 24V * 2.5A = 120WH (kbabin had that right)

Add if system ineffeciencies:

120WH * 1.5 = 180WH a day you need to produce (this may be a little high as you don't have an inverter)

Now to size the array/panel. I'm going to use 2 hours average daily insolation since you did indicate that there is shade problems. I suspect these would mostly be in the morning and/or late afternoon.

180WH / 2H = 90W By the indication of what panels you have available I'd use either 2 of the 40 or 50 watt panels wired in series to achieve 24V.

For the batterys, You want to only run on the top 20% of the battery so they last and this gives you 4 days of usage before they hit the 80% dicharge mark that damage to them starts to happen quickly:

180WH / 24V * 5 days = 37.5AH at 24 volts

2 little marine batteries wired in series should be fine. They would also need to be wired in series for 24V. I would stay away from the dual purpose batteries. They are only slightly better than regular car starting battery. Making a battery that works for both starting and deep cycle is about like trying to make a running shoe that is also a logging boot. While you might be able to do both, it does niether very well.

They only other thing needed would be a charge controller. Make sure it is also has a 24V rating.

Optional items would be a Low voltage disconnect. Many smaller charge controllers have this built in. Another would be a timer. Finding a 24V one might be hard but it would save the batteries should you forget to turn the pump off and leave the hose on or spring a leak.

WWW


----------



## byexample (Aug 28, 2009)

I recommend that you get the optional heat-sync for your Shurflo pump. Using those pumps for irrigation requires them running for long periods of time. Shurflo pumps will eventually shut off due to over-heating in agricultural uses. The heat-syncs do a tremendous job of keeping the pump cooler and thereby extending the life of the pump.

Another thing to consider is that the pressure switch on those pumps are crap. They die very quickly. So you might want to have a replacement pressure switch on hand if you are going to be dependent on this pump for irrigation. We actually by-passed our pump's built-in pressure switch and used a regular SquareD well pump pressure switch instead. It's like having a whole new pump.

One more thing to consider is that you might want to add a small pressure tank to your system to keep the pump from "cycling" on and off quickly when using water at lower flow rates. Cycling the pump for long periods of time will reportedly shorten the lifespan of the pump.

The advice and calculations above on number and size of panels, batteries, etc. all looks good to me for your needs.

Good luck!


----------



## Jim-mi (May 15, 2002)

. . . "dual purpose batteries" . . . . .????


----------



## Sparticle (Nov 1, 2004)

Thanks everybody. I think I understand all this. Great advice, thanks!


----------

