Battery Backup question

[GCouture]

Matt, 
    I wanted to add a couple of thoughts for you to consider:

• Xcel energy is giving an upfront rebate for whole house battery installations ~$5000
  
• Colorado has a tax rebate of 10%
  
• Federal rebate is 20%
  
• Whole house batteries can be set up to store energy when the energy costs are the cheapest. You can set them up to use battery power when demand is the highest.  This will save you money on your monthly power bill.  
  
• If you already have solar, they will charge from your rooftop generated power as well.  During multiple day off grid situations like we experienced recently, your panels will charge your batteries provided they aren't covered with snow.
  
• Most battery companies are providing a 10 year warranty where the capacities are guaranteed to be 70%.  Ten years from now, battery replacement costs could be a lot cheaper and maybe even better energy density.
  
• A whole house generac generator with a clean sine (utility grade) output can run $7k
  

Generators lose about ~28% at Bar K altitude(~24.5% in JT) so a 10KW generator is already running at 7KW.  Additionally, as you have mentioned, marginally sinusoidal outputs will lower the RMS power of your generator (if the waveform is more triangular) as well as the previously mentioned issues with ac motors that are designed to run on a clean sine wave. Our generator runs closer to 50Hz. Your motors will draw more current and run slower if the frequency is off like ours. Our pellet stove wails like a dying cat when we run it on our propane generator. (Minor exaggeration here but you get the point)  

It's a bit of an upfront cost but if you consider the rebates, the utility costs savings over a 10 year period, and the cost of a comparable whole house gas generator, the whole house battery is pretty attractive, regardless of the manufacturer.  The advantages of the propane generator are  they will run as long as you have available propane.  They do require service and maintenance.