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Community and Q&A

Solar Sump Pump

Michael Ritter | Posted in General Questions on

This isn’t really a green building question, but I know there plenty of informed commenters on this site so it’s worth asking here.  The World Wide Web didn’t have much to offer for viable solutions, so am turning to the expertise of this community.

We had 2 egress wells installed late summer and have come to realize with any amount of rain there might be several inches of standing water.  Not to a point where water rises to the bottom of the window and at risk of entering the basement, but enough to worry me about what it is doing to my foundation over time.  I just pumped about 45 gallons out of both of them so am looking forward to an engineered or mechanical solution that doesn’t involve me with a hand pump and a bucket.  I’ve talked to the installer and he can put in a sump pump, but his process has to penetrate my foundation for a power source, yet again, so I’d rather find a self-contained solution.  As a point of reference they dug a 12″ hole all the way to the footer and filled it with gravel when they were installed, so conceptually it should be finding it’s way to our interior drain tile system.  Part of the problem is there is a decent amount of groundwater where I live and we have very high clay content in our soil, so draining is a very slow process. 

This led me to believe there has to be a way to incorporate a smaller solar panel (110w?) with a 12v sump back up battery system.  The location is perfect on the southern facing side of my house and the sump batteries only use a trickle charge.  I was thinking I’d drill holes in the lid then bury a 5 gallon bucket as far down as I can, wrap it in a good fabric to keep sediment out, stick the pump in there, backfill with gravel, and then pump it to daylight.  If I was really ambitious I would trench a line between the two wells and plumb a drain from the pumpless pit to the one with the sump, but that is probably more work than just spending $400 on another pump and battery.  

So, am I overlooking anything or missing why this isn’t an obvious solution?  The wells will stay dry, so in theory I can store the battery in a case inside the well, maybe elevated on a platform I’d build just to be safe.  I’d have to penetrate the well cover to get power in and plumbing out, but should be able to make it waterproof enough.  

Thoughts on a simple setup for something like this?  Any recommendations on small standalone solar panels that will work for my situation?  Northern Tool has a 110w panel for less than $150, that will power 12v or can be used with a power inverter (included), so that seems like a decent deal.  So far the hardest item to locate has been a simple 12v backup that can be used as a standalone pump and that has the right kind of vertical float I need.  

If anyone has any comments, thoughts, or feedback they are warmly welcome.

Thanks!

Michael

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Replies

  1. Expert Member
    Akos | | #1

    110W is a big solar pump. You are not looking for a lot of GPM, just enough to empty out the well over a couple of hours. Something between 15W to 25W should do the trick.

    I doubt you'll find any specific solar sump pump but you can make one.

    I would look for solar pumps (meant for either pool heating of transferring water to storage tanks) that will run directly off a solar panel or solar fountain pumps. You can than add a float switch in between the panel and the pump to trigger it.

    Batteries are maintenance item, if you don't mind waiting a bit for the sun to come out, I would skip it.

    Properly detailed window well should not fill up. My guess is that the skipped the filter cloth and the gravel has become full of silt.

  2. Michael Ritter | | #2

    I will find out what they skipped when I get in there to dig it up but you could be correct. Honestly I'd rather find out that's the case and just correct it / bypass the need for a pump. There are also grading issues where they were installed that are soon to be corrected when we embark on an addition. I like your idea; however, if I find out the drain is working correctly and the water is simply up that high, I would like to have the pump buried as low as possible to remove as much water as I can.

  3. Paul Kuenn | | #3

    you first have to figure out the "head" which the pump has to overcome to get the water up and out. Those egress wells can be pretty deep. You can find a less expensive solar pump at 6 gallons/per minute and ask questions at Backwoods Solar. https://www.backwoodssolar.com/products/water-pumps?
    I use one for my stream but it's for a battery and I don't think most advise use directly from the PV panel unless specifically manufactured for such.

  4. Expert Member
    Malcolm Taylor | | #4

    Michael,

    As Akos said, Window wells are typically connected to the perimeter drains by an adequately large continuous layer of drain rock protected by some filter t0 stop clogging, or a floor drain directly connected to them. You want to do one of those two things properly before resorting to pumps. Relying on a pumped solution to keeping them from flooding, whatever the power source, seems like asking for trouble to me.

  5. Expert Member
    Zephyr7 | | #5

    +1 for trying to get things to drain without need for a pump.

    If you DO need a pump, I would recommend an electric backup-type sump pump, which runs on a 12 volt rechargeable battery (a marine deep cycle battery, which is similar in some ways to a large car battery). Wayne makes such a unit, and theirs has a good reputation. If you connect a solar battery charger intended for RVs with 12v electric systems (that means it will be a good-size solar panel and charger, probably at least 100 watts, and ideally more), that will keep the 12v battery charged. This type of sump pump will otherwise operate as a normal sump pump, even though such systems are typically used as backups for AC powered pumps when the power fails.

    If you have only very occassional pumping needs, a system like this should be sufficient. You need to BE SURE your solar panel can recharge the battery completely between pump cycles, and the battery has to be able to run enough pump cycles before the next time the sun can start charging again.

    I would think it would be easier to just run a conventional electric circuit to power a normal sump pump though.

    Bill

  6. Michael Ritter | | #6

    Thanks all. I'm still noodling on what I'm going to use for a solution. The more I've investigated and researched, the closer I become to agreeing with Bill and just running a circuit to the wells. Our exterior drain tile doesn't work or if it does it works poorly (1955 ranch with clay drain tile = clogged). There is an interior drain tile that was installed by the previous owner that does a great job of catching water. My foundation guy is coming by next week so I might just ask him to install an actual piped drain for both these wells to our interior tile. My issue with this is they have to bring the pipe in through the wall, so seems like a potential failure point in the future.

  7. C L | | #7

    Yes, a solar powered sump is sorely needed. Every time I search for one I'm shocked it does not exist. I'd like to collect rainwater and then use it to irrigate - I would control the irrigation pump via zwave so it irrigates only when it is not raining out, and want the pump to have a float or other device smart enough to not run when the collection container is dry.

  8. Michael Ritter | | #8

    I dug up enough to partially diagnose the issue. There is a drain, but it’s just black corrugated buried in the gravel that deposits at the base of my foundation Wall (not footer), where it’s clay. They also only filled about 18” of the rest of the well with gravel, then it returns to soil (again, clay in my case). So Akos was spot on in that the detail matters. I didn’t know at the time and the contractor seemed like he knew what he was doing with drainage, so I didn’t press him. I now realize the entire well and 12” around it should be gravel to footer depth. I guess when we put our addition on and have them here to dig that foundation, I will have them dig up this part of our wall too and correct this issue and hopefully waterproof the entire wall from the outside. Definitely going to want to waterproof and dimple mat as there is always hydrostatic pressure with the soil and water levels around here. I wonder if I can do all that with the egress wells attached or if I should pull them off? Looks like they’re fastened with Tapcons and rubber washers.

    In the meantime, spring is coming which means rain. Is it worth having my foundation guy pipe a drain from the well, through the wall, and tie into my interior drain tile on Monday? He is coming anyway to install a new hopper and do a few other things.

    We plan to start our addition in mid March so just need to make it to then and really don’t want to punch a hole in my foundation 12” from the footer - seems like a catastrophe waiting to happen. I guess I am wondering if swapping all the soil out for gravel is going to make a difference? Won’t groundwater still find its way into the gravel from the surrounding area?

  9. Tom May | | #9

    Go to a marine supply store and find a 12v bilge pump

    1. Michael Ritter | | #10

      Tom that is genius. The foundation repair guy is there today and he is going to properly plumb the drain line to my interior drain tile so that is our solution for now. We talked about addressing it from the outside, and that might be a future option but this is the fix I need for now to get me through the next couple months.

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