Imagine energy as water, voltage as pressure and current as water current and you relize that when you have a water pump at the end of the distribution line it will supply pressure higher than in the line. Water will flow from your little pump to your tap if you open it. If you keep it close it will flow to your neighbour or even farther if he is not there using it.
So wind turbine is your 6kW max pump, solar system is your 3.5kW max power pump. Problem is when both pumps do not run (no wind at night ) – then you need energy from grid. But if you can store few units of energy (imagine buffer tank ) you can stay independent for some time.
Below example from Gerrard’s setup co.Denegal. 4x160Ah lithium storage and power diverter dumping surplus energy to hot water tank (after battery is full and export begins ). Windspot wind turbine on 6kW SMA inverter and 1.5kW solar system (fronius inverter).
Energy consumption last 30 days (note is highier during high generation due power diverter):
Solar energy generation:
Wind energy generation (note scaled):
Actual exchange with national grid (ESB in this case):
Those are 30 days graphs, notice how little power is imported from grid. Gerard is not high energy consumer. Here you can explore this system on VRM.
Yesterday James in co.Sligo was swithced to hub2 v3 where system stays OFF GRID till battery level drops to 5% or load is higher than 5.5kW. Victron multiplus is connecting to grid then using his internal contactor. It can support grid aswell but that function if off at the minute as grid is very weak there and problems occuring. System goes back OFF GRID whenever battery gets to 30% or load drops below 2kW for 30sec.
From this morning turbine and solar were generating well so James started charging his nissan leaf (3.7kW charger). As you can see below consumption of 4kW over 5 hours equals 20kWh where 10kWh is battery capacity and rest was suppied directly from wind and solar. At the end of the day wind dropped (also no sun ) so system switched to grid.
Hourly consumption break down:
30kWh is capacity of Nissan Leaf battery so almost almost full independent charge I could remotely oberve today. Here is wind turbine monitoring from ABB vsn300 card (every 15min data). Here you can explore this system yourself.
Last example is Barry in co.Meath. 9kW solar system, 2.5kW skystream wind turbine and another 2kW of solar seems planty but what if you have 1.5kW swimming pool pump running exery 2h for 1h.
Consumption graph for last 7 days shows high energy consumption (40kWh per day !) but even this during windy sunny period is not a problem for this system as you can see exchange with grid is very minimal. Here is VRM for this system.
Last 7 days system consumption (note usage close to 10kW some days):
Exchange with grid:
Consumption break down:
All those 3 examples have same 5kW victron multiplus inverter charger (48V 70A max charge current).