Solar charger for 12v battery running shurflo

[NJG]

So glad to have found this thread. I've been looking into solar for my remote 4048 pump as well. I'm only around on the weekends so I need a set up to last all week without supplemental charging or swapping out a battery. The more I look into solar the more confused I get. This is what I'm thinking so far.....if I'm wrong I hope someone can let me know!

My 4048 pulls 3 amps when pumping water and 1.6 amps when running dry. Since it seems that the pump pulls both sap and air when on the mainline, I'm averaging this out to be 2.3 amps (27.6 Watts) over the course of a week. I'll also be running a temp controller this year and expect the pump to run an average of 12 hours a day.

I ran a test on the 120 ah battery I have and while running water through it (3 amps) the battery lasted 41 hours before dropping to 10.3 volts and the pump shut off. If I'm doing the math right, at an average of 2.3 amps (27.6 Watts) I would likely get 52 hours off one battery.

Here is where I get fuzzy on real life expectations of solar. Assuming I have a 150 watt panel and 4 hours of sun a day here in northern Wisconsin, if that panel puts out 50% of its actual rating, I would gain 300 Watts each day. Does that sound correct? My biggest worry at this point is how much the diffused shadows of the trees in the woods will reduce the efficiency of the panel.

If I'm gaining 300 Watts a day and loosing 331.2 watts by running the pump for 12 hours a day, I have a loss of 31.2 Watts every day. If I start the week at noon on Sunday with a fresh (1440 Watt, 120 ah) battery and loose 31.2 watts a day, I should have 1248 watts left over at noon on Sunday. This should give me plenty of wiggle room for those stretches of cloudy days.

How does this crazy plan sound so far? I'll take all the help I can get!

Thanks

[Biz]

There are so many variables, you could spend a lot of time trying to get everything right.... But I think the 150W panel will be more than adequate. No need to over think it. I know some who use 100W panels and never have to charge the battery during a season. Battery charge current varies according to battery charge state and will be less as battery nears full charged. so the watt-hours calculation isn't simple. And solar charging has a lot of factors like sun angle, panel angle, shading, type of panel, etc. I would just hook it up and see how it works out. My guess is 150W will be more than enough. I am going to try a 100W panel this year. My 70W panel wasn't quite enough last year for those extended sap runs. Neither was the 40W panel that I tried before that

Pump current draw will probably be on the lower end of the range since I believe the high power is only for high pressure/flow, not vacuum and pumping it a short distance downhill to the tank. My 4008 12-volt pumps draw less than 1.5A on a vacuum line regardless of flow, even though it is rated at 7.5A max. Yours would draw a little more.

Dave

[NJG]

Thanks for the info, I appreciate all the help I can get. Any thoughts on Poly vs Mono vs Amorphous?

Nick

[Biz]

I like the polycrystalline panels. They are cheaper and perform better if it is cloudy. Cloudy weather is when you need charging the most, because cloudy usually means sap (and the pump) is running overnight and you need charging the most. There are articles online that discuss pros and cons of the panels.

Dave