Many of our customers’ homes have flat roofs. For aesthetic reasons, the solar array is also expected to be flat, except with a small angle for rainwater to run off.

The problem with flat roofs at our Northern California latitudes is that solar production is very “peaky” in the summer: Solar production is 3 times higher in the middle of summer than in the depth of winter. At the same time, loads are typically higher in the winter in Northern California.

Northern California has too much solar energy in the summer and too little in the winter.

With California’s new net-metering scheme, exporting power to the grid makes little sense. Since exporting energy does not benefit the customer, why produce so much excess solar in the summer?

The YouSolar STEP™ Installation and Operating Manual shows how two panels can be connected to one STEP microconverter.

Therefore, we recommend that our customers with flat roofs use two solar panels on one YouSolar STEP™ DC-DC microconverter.

The “two-on-one” panel-to-STEP configuration saves money and cabling and produces nearly the same amount of solar energy the home can consume.

The graph below shows how much two 405 W solar panels of a flat solar array in Northern California would produce each month of the year and compares it to the solar production of two 405 W panels connected in parallel to one STEP micro-converter.

In Northern California, a solar array on a flat roof with two 405 W solar panels connected to one STEP™ microconverter only produces 15% less electricity annually, and most of that lower production is in the summer when the array produces more energy than the house can consume.

On an annual basis, the 2-on-1 array produces 15% less energy, but all that “lost” energy is in the summer when there is more solar energy than the house can consume. In the winter, both configurations produce pretty much the same amount of energy.

We use the STEP™ microconverter’s flexibility to create “smart” solar array designs that provide our customers with all the solar energy they need at the lowest possible cost.