"No Optimal Solution Found"

When you run a scenario, Keystone Designer evaluates the financial impact of purchasing and dispatching the equipment you have selected against your utility profile and utility rates to maximize the savings over the life of the project .  If Keystone Designer is not able find a way to increase cumulative savings by purchasing and dispatching the selected DERs, you will receive a notification after submitting your scenario that indicates "No Optimal Solution Found."  In other words, it is more cost-effective to continue using the utility rather than purchase, dispatch or replace the DERs with the chosen parameters.

This conclusion can happen for a number of different reasons:

1. The energy use profile and utility rates will not make any selection of DERs economically viable,
2. The specific fixed DER sizes or range of sizes are not a feasible solution for the given energy use profile and utility rates, or
3. The fixed DER sizes provided conflict with other constraints (e.g. asking for a minimum of X kW of solar but providing an available area that doesn't support that size installation).

Here are some ways you can adjust your DER selection or parameters in your next scenario to reach a more optimal solution:

Adjust the PV setting 

Orientations of PV systems matter.  Check the values you have chosen in your PV settings. If you are less experienced with PV systems, there are a some good starting points.

1. In Northern Hemisphere, azimuth should point face south.  An excellent place to start is 180 degrees (South). If you have orientation constraints, consider choosing an orientation between 90 and 270 degrees, as this will increases specific yield of PV system.
   

1. In Southern Hemisphere, Azimuth should point north. In this case, 0 (North) is an excellent place to start. If you have orientation constraints, any values between 0-90 degrees and 270-360 degrees will increases specific yield of PV system.
   

Adjusting the Battery Specifications

The two most important settings for the battery are duration and efficiency.

• Duration: Depending on your tariff, batteries with different durations may be optimal. For example, you would want a battery with at least a four-hour duration if your tariff contains a four-hour on-peak period. To calculate an approximate duration (hours) divide the capacity (kWh) of the battery by the discharging power (kW).
  
  
• Efficiency: Energy arbitrage via storage will not be cost-effective if the battery's efficiency is not comparable to the difference in energy charges. Since batteries are never 100% efficient, for every dollar spent to charge a battery, there will only be a fraction of that amount available to offset energy costs. 
  
  • Example 1 : Off-peak energy costs $0.08/kWh, and on-peak energy costs $0.09/kWh. A battery with a round trip efficiency of 0.75 will not perform arbitrage. The result is wasted energy and costs.
  • Example 2: Off-peak energy costs $0.08/kWh, and on-peak energy costs $0.09/kWh. A battery with a round trip efficiency of 0.98 will perform arbitrage because the savings by using the battery to cover the load during on-peak hours is greater than the amount lost to efficiency. The result is reduced costs.

Reduce the costs associated with the DER, if possible.

Lowering the unit cost (initial capital expenditure) increases the probability the given DER would be considered "optimal." If the asset unit cost is low enough and Keystone Designer still does not select it, you should consider this DER to be a non-viable option.