Design Project

[mrnewbie]

An un-educated guess on the water pump.

I have a similar 12V water pump..It's for the live well in the boat..old one died.

Its a 12V 7A pump made by par-max..it runs at 4.3GPM..which is a little more than this fellows 3.5GPM

So it requires 84 Watts. I think we can assume my pumps a little bigger than his..

I think you could safely use a min 80watts for his calculations.
You wanna be real safe go with 100w.

[Mike90250]

Pumps are all about flow rate and head. Change that, and the power requirements follow. A lightly loaded pump will draw a lot less power than then the same pump at it's full head limit.

[mrnewbie]

I can't argue with that.

My pump doesn't really have any other spec's
It is mounted below water level and does not have a head rating, it doesn't pump but a foot or so up. Its either made specificaly for boats live wells (or relabeled and sold as such with big price mark up)

I kinda assume his pond pump..is a submerged pump and realy just circulates the water..just like my replacement live-well pump

We won't know for sure..untill he provides the info..

[mrnewbie]

Why it costs so much.

Lets assume your pump is 12V 6A(not 60)=72w (call it 80watt)

An 80 watt panel now runs pump..when the sun is out..(solar isolation of 4hrs/day)

Now you wanna run it 24hrs a day, Ok

You need to GENERATE and STORE power!

GENERATE..24hrs or energy in just 4hrs(solar isolation), you now need 6 times the solar panel just to generate (6x4)..it cost about $3 per/watt at best....you have now increases your costs by a factor of 6. At $3 bucks a watt this is no big deal...but..keeping the power!

STORE.. not doing the math lets just throw out a number..lets call it 144.
Lets assume you need a 144amp battery to store 24hrs worth of GENERATED power. great you go buy a 144A battery ..think your all set...WRONG!

You can't use all 144amps from the battery..the battery will self destruct.
It is recomended by most here to not exceed 10% usage of battery..or battery will have a real short life..and self destruct

You now need 10 times the battery so as to not exceed the 10% usage

So you now need 6 times the panel and 10 times the battery ...for one day

What if you have no sun for a few days? (don't wanna fry battery). Well to compinsate for this you need to..increase the solar panel charging rate and battery storage ..just for a few day backup...

Gets real expensive..

[Huntington]

I had a death in the family and had to step away from this project this last week. Sorry for not providing more info earlier but I just got an update.


I got some clarification from #### ####. I still would like to stick to my original plan. Provide him power 24/7. But he is cutting you a slack if the cost is prohibited.

-----------------
Prof. ######

Hi #####,

Regarding the wattage, I don't think we established any kind of cap. If we have more, we can certainly use it. We are currently working on the assumption that at its peak, we can generate 65 watts from the existing panel. Our immediate needs:

(1) 12V/2.8 amp water pump that has about a 6 ft lift and move about 500GPH (can be daytime only, as it is now, unless surplus power can extend that into the evening--anything additional time is great, but not a project imperative if we have no additional time. We are close to having this level of performance now with the existing panel.
(2) An electric fan to move air through the large greenhouse (daytime only)
(3) Workbench lighting inside the greenhouse (night time only).
----------------------

We would like to make this system 24/7 but the priority is listed above.

1) The pond is about 3 feet deep. The pump is needed to provide mixing. The total vertical lift that the pump has to achieve is about 1.7 meters and maintain about at 500 GPH flow. Bilge pumps are 12V devices that pull about 2.8 or so amps.

* I am thinking about not using a battery to provide night time operation; instead maybe a gravity feed system. Pump pumps all day into a tank, the tank feeds the pound, the reserve water in the tank feeds the pound for part of the night.

Im working on numbers for the greenhouse and trying to estimate needed airflow for the fan. Like I said the current one is ac and not using an inverter would be nice.

[Jarod]

Im working on numbers for the greenhouse and trying to estimate needed airflow for the fan. Like I said the current one is ac and not using an inverter would be nice.

Do not considering the fan,
only pump need 360W solar panel and a 340 AH/12V battery to work 7*24.
consider the fan and lights at night,
may need a 500W solar panel and 500 ah/12V battery maybe.

[Mike90250]

A bilge pump may only run for a day or two before reaching it's end of life. They have (generally) brushed motors, and are only designed to run for a couple minuntes at a time, maybe a 5% duty cycle.
Another possibility is a "blower" that can deliver air to below the surface, and the rising bubbles stir the water. This is used in many filters to move water and the pump motor stays accessable and water free.