Tesla roofing tiles for 40kW solar roofs

Tesla's merger with Solarcity has now gone through and this will mean big solar on houses.  And when they mean big they mean upto 8 or 10 times what is being installed today.  From add on systems that are commonplace now Tesla in the new year will be offering solar tiling which covers the entire roof from ridge-lines to gutters, which would provide capacities in the range 20 - 40kW.

Solar systems sizes have been growing and growing. In Australia back in 2007 with newly introduced feed-in-tariffs coming into play one and one and a half kilowatt solar systems were the norm. They could contribute to the equivalent of about 25% of a household's annual energy on a net basis and might offer direct consumption of 50%.

In 2016 most customers where they've got the roof space for an easy install are opting for at least 5 or 6kW and many are choosing to go for a full 10kW. Though now the limitations don't seem to be householder motivation or price but willingness of grid operators - the owners of poles and wires to let the customers hook in larger systems. 

"It seems that grid operators are coming up with convenient excuses to limit grid systems, these limits are arbitrary but the grid operators try and claim some technical basis for them."  said Paul Szuster Executive Director of Pure Electric Solutions a company that aims to get customers to zero grid imports which includes installing big solar.

What solar roofs at 40kW means is that winter performance in clouds will be amazing filling up batteries and running daytime loads - and Tesla of course is primarily a battery company, big solar and fast electric cars drive battery sales.  This means that systems will be oversized so in summer we will actually throw excess power away.  This is so that too much money is not spent on grid capacity / grid access or on battery inverter capacity that will never be used. Oversizing means power is thrown away but only at a time when everybody across the grid has too much power.

A common configuration might be 266% oversizing of the inverter which will be about 15kW but the inverter itself will be grid limited to only send a maximum of 7.5 or 10kW to the grid. This is so that the grid doesn't have to be built any bigger for all the solar systems. We must be careful to note that 10kW of gird capacity as offered by Victorian distributors Jemena and United is completely doable or else they wouldn't be doing it. As part of this revolution our governments whether they be state or federal need to guarantee everyone 10kW of access to the grid.