Changed solar kits to used DS3-S microinverters for better DC/AC ratio

Travis

Hey all,

After some feedback and consideration, I decided to make some changes to the design of the solar kits.

Previously, all kits were designed using the APSystems DS3-L microinverters which are 748W. The DS3-L, paired with two of the 410W panels, this resulted in a DC/AC ratio of 1.06.

I've now added the APSystems DS3-S microinverter to all solar kits (and made it the default). The DS3-S has an output of 640W, paired with two of the 410W panels results in a DC/AC ratio of 1.28.

Using this new system design with a DC/AC ratio of 1.28 is recommended. Undersizing the inverters like this (especially in northern latitudes) is an industry standard and benefits basically everyone. This will especially help folks in Alberta where their interconnection permit only allows a certain AC system size, and having a higher DC/AC ratio will allow them to produce more kWh for the year. This also helps folks in Ontario where the max AC system size is 10kW.

If you would prefer to order a solar kit with the DS3-L microinverters, I've made this possible - every solar kit can be modified and both microinverters are available to select from.

Let me know if you have any questions.

Travis

A couple more changes::

I changed the default panels for all solar kits to be the JA Solar JAM54D41-440/LB, 440W ones, since they're significantly cheaper than the Longi 410W and weigh about the same. This results in a DC/AC ratio of 1.38.

I also made some changes to the DIY Solar Guide:

Changed "Roughly Calculate Your System Size" section to calculate DC size instead of AC size.
Added a "Design Specifics – Which panels and microinverters to use, and what is a DC/AC ratio?" section to better explain DC/AC ratios.
Added a "Design Specifics – PVWatts Calculator" section which includes DC/AC ratio in calculating more accurate annual kWh production estimates (which can be used for micro-gen applications).