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Get Powered Up! Certified Energy Manager Jeff Yago answers your alternative energy questions

Wondering about a great new energy-saving device
you found on the Internet? Then CLICK HERE!

Sorry. Jeff no longer answers questions online.
This will remain as a searchable
resource for all BHM website visitors.


Solar-run water purification

Sunday, September 7th, 2008


I was wondering what batteries you believe would work best for a solar run water purification unit. Are there ion batteries available? They must be sealed and ranging from 160 to 200 amp.

Thank you

Devera Denker


Sorry, but not enough information to make an informed guess.

Sealed could mean AGM batteries which are better for “float” service where batteries are kept at full charge and only occasionally need to be discharged. Sealed gel batteries are better for daily cycling and cold temperatures.

You did not indicate voltage and amp load of purifier, if the battery will be charged each day, and if it will be deeply discharged each night. Will it provide power for several days with no sun and deeply discharge, or is the load small in comparison to battery capacity?

Batteries are usually sized based on their voltage and amp-hour rating. Saying 160 to 200 amp would normally mean the load is this big, but most water purification units that use ultra-violet light are usually a small power load so I assume you actually mean 160 to 200 amp-hour. I also assume this is a 12 volt DC system but you did not say and this would change the number of batteries in series or parallel.

Not sure what you mean by ion batteries unless you are talking about the small lithium-ion batteries. These do not like to by cycled very deeply and will only last about 2 years.

Hope this helps,

Jeff Yago


Pumping water in Brazil

Wednesday, September 3rd, 2008

I live in a semi rural area in Belo Horizonte, Brazil (lots of direct sun) and am interested in pumping my water from the closed reservoir to the holding tanks above by solar power.

The head is 105 feet at a distance of 350 feet through a two inch PVC pipe.

I see Northern Industrial Tools has these High Wattage Solar Panels – 15 Watt With these panels as a start, what else do I need?

Thank you for your help.

John D Martin


I realize you do not have easy access to many specialty suppliers, but unless you plan to buy a trailer truck load of these 15 watt modules, you need to re-think this project. Although you did not indicate the amount of pump flow you required, which determines the pump size and in turn the pump’s power requirements, you did indicate a fairly high pump head and large pipe size which tells me you will need a pump that will require far more power than you can achieve with these small modules.

First, determine the size pump you need and voltage. As a starting point, I am making a wild guess that you will need at least 150 to 200 watts of solar modules wired for a 24 volt pump, which would be better to use two modules at 75 watts each, or 4 modules at 50 watts each to reduce the wire and mounting issues of using many smaller modules.

There are many solar pump suppliers that can provide you with a complete packaged system with pump, controls, modules, and mounting if you can provide them with more details on the pumping requirements you have. Since you are pumping up to a storage tank, you may want to use a smaller flow high head pressure pump and smaller pipe and let it run all day than a larger pump that quickly fills the storage tank and shuts off, since this would require a smaller solar array and have a lower cost. Contact Dankoff Pumps

Good Luck!

Jeff Yago


Generator question

Monday, July 14th, 2008


I have a home with a year around stream running beside it. I am sure I would not be permitted to dam the channel, but I am wondering if I were to have a 3″ pipe with about 8′ of fall suspended in the flow, and a 1/2 hp deep well pump mounted on it and driven by the water flow, would it act as a generator? the lowest flow is probably about 10 gallons/sec.

Dave Mckee



You cannot make an AC well pump generate electrical power no matter how fast you run water through it. The reason would take me 4 pages to explain but its due to the basic theory of operation of any AC type motor. It is possible to cause a DC motor to generate electricity if you drive its shaft, but I really doubt you have a DC well pump since these are only used with battery and solar power systems. In addition, most modern pumps, regardless of AC or DC operation, use a magnetic shaft drive to allow sealing the pump section from the motor section, and I am not sure how well this magnetic drive will work in reverse.

Now for the good news – If I lived right next to any stream that flowed 10 gallons per second, you can bet I would have already purchased a water turbine generator. There are many manufacturers who make many different sizes and types of these generators. If your stream and land has lots of fall, most people extend the pipe upstream as far as possible to achieve any more flow, since a lower flow at a higher head pressure is usually more effective in generating power than a higher flow of a lower head pressure. Again, lots of technical reasons why this is so, but if your stream really is year round and you can extend a pipe to a higher upstream position you should do this.

Here are a few sources for more information:

Good luck!

Jeff Yago



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