Solution Services: Energy Efficiency Measures

About Energy Efficiency Measures

Energy efficiency measures are a third energy system type that can be modeled in SolarNexus, alongside PV and energy storage systems.  An efficiency measure is any type of work that will reduce the expected consumption of the customer's site.  An efficiency measure can be a the replacement of some equipment with a more efficient model, or can even be as simple as a change to the operational schedule of equipment.  A solution may contain one or more efficiency measures, but it does not have to have any.  Energy efficiency measures allow you to incorporate the energy savings of a given measure into your customer's overall solution and subsequently see its financial impacts included in the SolarNexus analysis.  These savings can apply to the electric, non-electric, or both energy services (for example, natural gas for winter heat, and electricity for summer cooling).  Because efficiency measures cover a very broad number of possible technologies, SolarNexus does not currently provide any tools for determining estimated savings from any specific efficiency measures. Those savings must be determined through the use of other tools or calculations, and then entered into SolarNexus for evaluation of their economic benefits for the customer.

About Base and Seasonal Heat/Cool Loads

“Base load” is defined as the portion of monthly energy that stays relatively constant throughout the year.  It includes loads like refrigeration, cooking, laundry, lighting, water heating, and plug loads.  Heating and cooling loads can be significant, but they vary by season.  Knowing the base load helps users to understand relative sizes of the clients’ monthly loads, and allows SolarNexus to determine percentage savings on seasonal heating and cooling loads.  For example, programmable thermostats can save a percentage of monthly heating/cooling loads.

Base Load + Seasonal Heating/Cooling Load = Total Load

SolarNexus uses a "rule of thumb" calculation recommended by the department of energy for separating customer energy use into base and seasonal loads.

NOTE: If you use the Monthly Average or Annual Average input option for customer loads, SolarNexus has no way to estimate differentiation of loads. So in this case, SolarNexus does not support a differentiation of base and seasonal loads. Therefore, seasonal load savings cannot be estimated when you use either of the Monthly or Annual Average input methods.

Add / Edit Efficiency Measures

Efficiency measures are managed in much the same way as PV systems.  Click the Add Efficiency Measure button at the top of the Systems screen below the Solutions’ summary. Each solution may contain more than one Efficiency Measure.

You may select a predefined efficiency measure service offering, or create one on an ad-hoc basis.

Efficiency Measure Editor

On creation of an Efficiency Measure service, SolarNexus will show the Efficiency Measure editor screen:

If you created an efficiency measure from a pre-defined Service Offering, the fields are prefilled in.

Otherwise, the Name field is required and it should be used to define the service your company provides.  The Description field is optional. Use the description field to describe the scope of your service offering. For example, in the case of a service to upgrade a customer's main service panel, your description might be "Contractor will provide labor and materials to remove and replace existing main electric service panel with a new one that can support solar and energy storage systems.")

The Energy Savings section has a column for each energy service defined.  If a second energy service (e.g. natural gas) is defined, a second column will also appear.

The first step is to indicate which component of the customer’s load (Base Load or Seasonal) will be affected by the defined measure for each of the energy services.  If Type of Load Affected by Measure is “None,” the energy service savings section controls are disabled (e.g. for measures that have no energy impact on that energy service).

The Calculate Savings Button

The Calculate Savings button provides a simple way to quickly calculate all twelve monthly savings values.  Users may choose to manually fill in monthly values instead, if desired.    Any blank values will be considered as zeroes, or no change to the energy consumption, although you must enter at least one monthly value (or use the Calculate Savings button to calculate all months).

View of Efficiency Measures on the Systems Screen

On saving an Efficiency Measure, you will be returned to the Systems screen.  Efficiency Measures are listed below the PV System and Solar Thermal System summary panes.

The Energy Efficiency pane shows the type of energy service, the type of load affected, the annual savings (units based on energy type), and that savings as a percentage of the historic total.

Efficiency services can have automatic cost item synchronizations between items in an Efficiency Measure and its associated cost item group. Assuming the measures you are specifying include additional materials or labor costs to the customer, you will likely want to include energy efficiency-related Products in the Cost Estimate. See Defining Service Offerings.

Analysis and Interactions with Other Systems

SolarNexus incorporates energy efficiency savings into post-project use and bill calculations for the electric energy service, as well as non-electric energy service, if defined.  Savings across all defined Efficiency Measures will be summed together.

SolarNexus supports hourly modeling of EE measures, but currently in a limited way. SolarNexus currently assumes the EE measures have the same hourly profile as the energy use. So if you define a measure that has 10% monthly savings, that will get reflected as 10% savings within each hour of the day. That’s obviously not entirely correct, but its a reasonable estimate for most client instances.

The benefits:
* We can show the hourly savings data in the graphs
* We can include efficiency savings in the battery simulation — we subtract the efficiency savings from the original load before passing it into the simulation, so the battery simulation is operating on post-EE load
* If the user selects something other than the "Typical for Location" load profile (OPenEI or a custom profile), the efficiency savings will align with the usage. Previously, this would have meant using one profile for usage but the Genability profile for savings. Theoretically, this could result in negative load in some hours.

NOTE: In the future, SolarNexus will allow the user to specify a custom hourly savings profile for each EE measure.

Current Limitations

Currently you can enter a % or kWh amount, but in the end we resolve it to a monthly kWh amount that is being applied to the hourly load profile. But let’s say you have an EE measure where all of the savings happens in the evening AND we let the user input a total kWh savings amount for the month and then apply the selected hourly profile to it that distributes the savings only between 4pm-9pm, what would happen if, for argument’s sake, they also chose a load profile that had almost no usage in the evening? If the load profile said there was 1 kWh of usage at 4pm but the efficiency profile said there was 2 kWh of savings, you end up with -1 kWh of usage, which is invalid.

In practice, it won’t usually be that stark, but you could still end up with unexpected results.

Another problematic scenario is when usage is defined by Green Button. In that case, the hourly usage profile and hourly EE profile won’t align. So you could have an hour in the day where the EE profile says there will be 0.4 kWh of savings but where the Green Button data says there was only 0.1 kWh of usage. (Maybe the customer was on vacation, so had no usage during an evening hour when they normally have high usage.)

In this case, we’ll treat this hour as having -0.3 kWh of usage, which will get counted as a credit in the bill calc. It’s not great, but should generally come out in the wash in the monthly bill calcs. (Some hours might have a bogus “credit” due to EE savings misalignment, but others will have less than expected savings, so it won’t generally be noticeable.) However, this scenario is more problematic for a battery simulation - where the battery simulation does not handle hours with negative usage. So for now, SolarNexus disallows you from adding both storage and EE when the client's use is defined using Green Button data.

How Efficiency Measures Affect Self Consumption

The self consumption % shown on the System screen is based on post-Energy Efficiency load.

So if you have:

• Original Load: 10000 kWh
• PV Production: 6000 kWh (50% of which is self consumed)
• Efficiency Savings: 2000 kWh

That means:

• Post-EE Load: 8000 kWh
• Self consumption: 3000 kWh (= 50% of 6000 kWh)

So you’ll get:

• Load Offset: 80%
• Self Consumption: 37.5% (3000 kWh / 8000 kWh)