Journey to Solar - Part 1 - Understanding your usage and getting skinny

I manage a group of homes/ranches as a side hustle - and recently started down the path for one of my clients of researching the aspects of adding solar power to the home.

The solar market has really matured in the last 5 - 10 years.  Prices for PV Panels has dropped considerably and there are a wide range of both DIY and One-Stop shop companies to choose from.

For residential energy alternatives - especially here in AZ - solar seems to be the obvious choice and with the addition of storage capabilities like Tesla's PowerWall - you can seriously start to look at the potential of minimizing your reliance on the utility grid for energy.  To me the combination of Solar Generation plus battery storage is potentially very compelling.

With that said - there is a lot of due diligence and additional expenditures in preparing for solar that I learned and will discuss here

While you can go to many sites and just enter a monthly bill amount and have a tool spit out a system size and price quote - you really need to understand what you actually need, what can fit on your roof and what you can afford.

Let's first start with understanding what you actually need and where it may be best to invest first.  Your utility web site, billing history and usage tools are a great place to start.  By collecting this info and doing some basic math - you can get a clear understanding of your usage.  If your goal is to minimize your electric consumption from your utility you have to look at both your total kWh usage for any particular month or day as well as any one hour in that day.  From that you can begin to see usage patterns and time of day consumption that can really effect your current electric bill and that would influence your design decisions for a solar system.

But it also provides you with information that are opportunities to improve efficiency or "get skinny".  This is as important if not more so than putting in a solar system itself.  With every home there are typically systems that consume more energy than they should and need repair or replacement.  You can in most cases dramatically reduce the size of the solar system you need by investing in those repairs or replacements first.  This will both A) save you thousands on your solar system and B) improve your efficiency while maintaining the lifestyle you want.

Here in AZ the biggest single consumer of electricity is HVAC and heat pumps are a very common installation here.  In my case - my client had two nearly 20 year old systems that where rated at 10 SEER. By replacing those units - we saw a dramatic reduction in energy consumption.  Combining that with Smart Thermostats and joining the utilities remote energy control program - where they can control the thermostat for specific hrs in the day for a billing credit.  This change alone reduced the potential number of solar panels and therefore the cost and complexity of the solar solution.

But you don't have to go overboard on HVAC.  Today - many states - like here in AZ have a mandate for the minimum SEER rating for new systems which is 14.  The industry has been pushing well beyond that with many systems available @ 20 SEER or higher.  That improved efficiency comes with a pretty large premium in terms of cost with very long ROI cycles - often well beyond the system warranty window.  So buying the top of line SEER rated system may not be the best choice.  As you prep for solar you want to try and avoid massive spikes in energy usage - so for HVAC - features like constantly variable air handlers that use lower energy amounts but may run longer or all the time may be a better choice.

Once you've covered HVAC, then you need to drop down to the next level of electrical consumers - typically refrigeration and devices like pool pumps.  Again investments here in efficiency definitely are worth it.  The final level is typically around things like TV's, LED lighting, Ceiling Fans, etc.   An example of this is for my customer - I had the home in what I called shutdown mode - the home empty - HVAC, Water Heater, etc in Eco mode, etc.  So the only thing running in the home where things like Fridge(s), Ceiling Fans.  In this mode the home only consumed about 10 kWh total from 6A to 10P some many hours where at 400 - 500 watts for the hour.  But when the pool pumps came on @ 10P - the usage jumped to nearly 4kW and in the 8 hrs the pumps ran - the total energy usage nearly tripled - to 34kW.  So while 4kW is a relatively small draw - when you're thinking about - could I be running off a storage system instead of the grid - then it impact things.   By changing to a modern variable speed / variable flow pump - that number dropped to 350W.  Now does the pump have to run longer to meet the proper turn-over rate for a pool - yes - but now it's a much more manageable amount of power.

If you want to get really granular in understanding your energy usage - you can look at tools like Sense - which connect to your electrical panel and can actually tell you what each circuit is consuming and where you can potentially make changes to improve your efficiency.   

In addition you're starting to see new "Smart" Panels come to market by major electrical players like Leviton as well as new start-ups like Span.IO.  These devices give you granular monitoring and control over your electrical circuits and some are integrating components that you'd need for a solar/storage installation to reduce the complexity and footprint.

Bottom line - Get a very good understanding of what your current energy usage is and then make investments in your largest consumers to improve efficiency.  By doing that first - you can reduce the potential size of your solar solution and still achieve your alternative energy goals..

In Part 2 - I'll discuss panels, inverters, gateways & some of the more geeky stuff.

Cheers.