Hi
I finally ordered some parts and got round to trying to get this set up in the first of the greenhouses, to be replicated in the others all being well.
So after a lot of trial and error and faffing around I set up a system of hosepipe attached to a long bamboo pole along the apex of the greenhouse. In this hosepipe I drilled small holes and attached "sprinkler" nozzles to create a spray kind of effect. The water is pumped out of the 180l rainwater butt to the hosepipe along the apex which is a height of around 2 metres. It is just an inexpensive 12v battery pump so the pressure is not great but it is ok and I will try and refine things a bit in the other greenhouses.
There is an electrical timer and 12v battery, the timer works ok, just need to wire it up properly so it will switch the pump on and off at the set times. The solar part I did not include to try and keep costs down.
I wanted to go with the spray effect instead of drip feeding since we have some pots in the greenhouses and felt that spraying gave a more thorough soaking all round the greenhouse although the reality is the water pressure means there are still dry spots, although the set up is a work in progress and will hopefully benefit from tweaking some more.
The timer is set up for 10 mins in the morning, this doesn't have to be up and working until May which is the target date when we all go away!
So in total for each "system" I use the following items: ~3 m hosepipe. Adaptor hosepipe to the pipe the pump comes with. 12v rechargeable battery. Electric timer. Battery charge indicator. Wire. Various electrical connectors, bulldog clips etc. Weatherproof box so that I can put all the electrical parts intio so the contents are not affected by the weather. 1 x 8 foot bamboo pole. Wire to attach hopepipe to pole. 12v water pump. Filtration bag to put pump in so it doesn't clog up with the rainwater from the barrel. PVC tape and wire to attach pipe to greenhouse on the way up. Misting fittings to attach onto hosepipe.
The only real complaint is the cost. I hope things like the pump are not going to break after only a few weeks etc. It is an interesting exercise and learning experience but not convinced it is really value for money... however it seems to be the cheapest way I can do it bearing in mind the limitations of the site I am doing it on.
I will keep posted after the end of the summer and report back whether it worked ok or not!