Our case is slightly different from Todd's.

The piping was bored down to the first available porous layer (they basically kept going until the mud and sand they were squirting all over the yard turned into water).

The two options for a pump were then either a surface pump or a submerged pump. The latter is better, since it doesn't require any force to raise the water before the supply side - however we opted to use our previous surface pump to save money. Despite a 35 meter rise before the supply side we still get good pressure.

The pump itself generates the pressure for the domestic system. In our previous well we had a smaller borehole and thus on the supply side of the system we had a small pressure tank which evened out the pressure delay between a tap being opened and the pump bringing the system up to the correct pressure. In our new system, the borehole and pump can supply full pressure almost instantly so our installer suggested we didn't need a pressure tank.

Our water heater is a solar deposit system which uses a heat exchanger to step down the stored, heated water from 80C to domestic temperatures. A water heater doesn't provide pressure; that comes from the water pressure maintained by the pump or domestic supply.

The solar system is backed up by a propane deposit which cuts in automatically if solar supplies are insufficient over a few days. The entire system supplies domestic hot water and central heating. Mostly 7 months a year it is 100% solar energy. The rest of the year, depending on conditions, it can be 30-40% solar with the propane supplying the shortfall.

As I mentioned in the previous post we're still on grid for our electrical needs. If we have a long term power cut, the only solution at the moment is to plug in a generator which can supply all the essentials (water, solar system, some lighting) but we plan to invest in photovoltaic systems specifically sized to run the pump, the solar system and with enough reserve for some lighting and small electrical items which would mean that if the power went out .. forever ... we'd still be ticking over.