SOlar watering system for the allotment...

[chriscross1966]

Hopefully (and I've kind of got to even if I have to deal with downpours while I do) I'll be getting a sort of mesh sided polytunnel established on the plot this weekend for my melons... in order that I don't have to get up there every day (not practical) I knew I was going to need some form of autowatering.... as I've managed to pick up a cheap twin-zone unit for use at home on the greenhouse it frees my two older units up to use on the plot, so I've been acquiring bits to make it work.... central to this was an IBC tank, plus a central heating header tank and a hot water gravity system header tank... One of them is quite large, the other rather smaller....

The plan is that the IBC will be a bulk tank, the bigger header will be fed by a solar powered fountain pump, the overflow from that will go to the small header, the overflow from that will go back to the IBC, the header tanks will normally sit on top of the IBC, the fountain pump plugged into its outlet with an IBC to hoselock adapter on it... The fountain will be powered by a small solar panel rated to be plenty for the fairly small pump.... Did a test with a car battery this evening Adan the pump had no trouble shifting water up a metre and a half head, which is as high as it needs to and in an approximate timed test it shifted a gallon and a half or so in a minute.... With the big tank being 22 gallons I think that means that it will take around 15 minutes or so of sunshine in a day to fill the big header and another four (for the small one...)...

The idea is that during the days the watering timers are off and any sunshine causes the headers to fill. At night (I'll probably arrange for it to be a bit after sunset) the watering times will turn on. The polytunnel gets the big tank every day, the celeriac gets the small tank every other day... By putting the overflows in at sensible heights it's about 200 litres every two days, so average 100 litres per day... a full IBC gets me ten days, all I really need is to know it's OK if I'm off at a festival for a week or so .... also have got sneaky way to fill it ... the polytunnel will be guttered and the water will end up in a couple of 225 litre tanks, from there using a car battery and a bilge pump I can pump it into the IBC... also one of the 225 tanks is dropped into the ground so I can wheelbarrow using an liner tank in the barrow and take 80 litres at a time into the lower tank.... Bit OTT, but I want to get it to work properly.... I've schemed up some ideas using ballcock valves Adan ballcock controlled microswitches to link all the tanks together, it would have the advantage of giving me a 1700 litre watering system at the point I had to leave it, but I'm not sure I need the two weeks plus that would give me..... unless I add another tank to water something else...

[chriscross1966]

[caroline7758]

Good luck with getting some sunshine!  :(

[picman]

Chris  Interesting project, You have not mentioned any Solar charge controller ?  A PV panel will produce 19v in full sun . I pump from a large poly container ( enough for 4 days) for 10 sec every 3 hours between 11 am to 5 pm to 7 tomato plants,( my own electronics ).
 

[chriscross1966]

No need for a charge controller, the pump is enough resistance to stop it going too stupid and the thing will circulateall day happily, it's rated for continuous use.... I think I've worked out a purely switche and relay system that will allow me to control the rest of it.... I might put a xener in there for the relays, but then again, shouldn't need it....

[picman]

Chris, "No need for a charge controller,"   ???

You could still get 20v spikes across the 12v battery , a high wattage 14v zenner diode across the +/- could help...

[Deb P]

You are all speaking in tongues to me...
I tried using those drip type systems as I have.no  hope of ever organising anything more complex, but they have 1 lite bags dont last more than 24 hors At best,...sigh.  I do admire you Heath Robinson types! ;D

[chriscross1966]

Chris, "No need for a charge controller,"   ???

You could still get 20v spikes across the 12v battery , a high wattage 14v zenner diode across the +/- could help...

No battery in the system... the pump is designed for use with solar panels and will effectively be watercooled. I've got a massive filter in the water feed to the pump in there too... THe idea is that as long as it fills the header tanks during the courseof a day then the normal (fairly cheap) watering timers will turn on in the evening and empty the tanks.... with  a six foot head I don't think I'll need to worry about the valves not openingong on the one hand or needing pressure reducers on the other

[picman]

Chris .... Now I get it  ... Les