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Solar Profiling

Solar Profiling. Interstate Renewable Energy Council presentation to the ERCOT Profiling Working Group Jan. 22, 2008. No one solar profile fits.

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Solar Profiling

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  1. Solar Profiling Interstate Renewable Energy Council presentation to the ERCOT Profiling Working Group Jan. 22, 2008

  2. No one solar profile fits • Example – customer in a class with a flat profile who averages 5 kW installs solar. Actual daily load shape depends on whether he installs a system with rated capacity of 2 kW (blue), 5 kW (green) or 8 kW (red) • In this example, there is no outflow for the 2 kW or 5 kW systems, so using the standard profile with the inflow data would just give a flat line profile. • For instance, a 5 kW system would generate 25 kWh in a day. Daily electricity use of 5 kW * 24 hours = 120 kWh would be met by 95 kWh from the grid and 25 kWh from the system. Profile would say customer used a flat 95/24 = 4 kW, which is inaccurate 5 kW 4 kW – inaccurate profile for customer with 5 kW system 0 kW 6am noon 6pm

  3. How to fix it • Recognize that metered data for inflow minus outflow is only part of customer’s electricity consumption • Inflow minus outflow plus generation is total electricity consumption by customer. It is appropriate to use the class profile for this total electricity consumption for the customer • It appears that there is problem: we don’t have metered generation data • To solve this, estimate generation based on system size. Add that amount to inflow minus outflow and apply the profile, then subtract the estimated generation using a solar profile (like the curves on the last slide) • Sounds complicated and hard to automate, but there’s an easy way to get to the same result

  4. The Easy Way • Apply the standard profile to inflow minus outflow then make an adjustment based on system size, either to the customer’s ID or to a new zero balance ID • For instance, from the first slide, the customer with a 5 kW system will reduce load about 25 kWh per day. Instead of seeing metered inflow of 3,600 kWh per month (5 KW * 24 hours * 30 days), metered data will be about 2,850 kWh (30 days * 95 kWh). Apply the daily profile based on that consumption and the daily system totals. The flat profile would come in at around 4 kW. • Then apply a solar adjustment (separate ID?) that adds 25 kWh flat and subtracts 25 kWh in the shape of the solar profile. • One adjustment methodology for all classes – reasonably accurate, very easy to implement, low cost

  5. Step–by–step for 5 kW system • Use standard flat profile for metered inflow minus outflow, which will be about 95 kWh - a flat line at just under 4 kW (minimal actual outflow in this example) • Add 25 kWh over all hours evenly – adds just over 1 kWh each hour, getting us to daily electricity use from the grid and the system at 5 kW • Subtract solar profile for 5 kW system – the green line below 5 kW 4 kW – profile based on inflow minus outflow data 0 kW 6am noon 6pm

  6. Step–by–step for 2 kW system • Use standard flat profile for metered inflow minus outflow, which will be about 110 kWh - a flat line at about 4.6 kW (no actual outflow in this example) (based on 2 kW times 5 hours equals 10 kWh of generation) • Add 10 kWh over all hours evenly – adds about 0.4 kWh each hour, getting us to daily electricity use from the grid and the system at 5 kW • Subtract solar profile for 2 kW system – the blue line below 5 kW 4.6 kW – profile based on inflow minus outflow data 0 kW 6am noon 6pm

  7. Step–by–step for 8 kW system • Use standard flat profile for metered inflow minus outflow, which will be about 80 kWh - a flat line at about 3.3 kW (no actual outflow in this example) (based on 8 kW times 5 hours equals 40 kWh of generation) • Add 40 kWh over all hours evenly – adds about 1.7 kWh each hour, getting us to daily electricity use from the grid and the system at 5 kW • Subtract solar profile for 8 kW system – the red line below 5 kW 3.3 kW – profile based on inflow minus outflow data 0 kW 6am noon 6pm

  8. Conclusion • No need for inflow and outflow data – just need the net figure (one meter reading) • Use standard profile for that net metered amount • Adjust that ID (or make a new ID) to add (system size * 5 hours / 24 hours) to each hour. • For 15 minute segments, divide by four and apply to each segment • Subtract solar profile times system size

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