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Net Billing: Credit expiry and same month credit application (Inflow/Outflow) #1200

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merged 4 commits into from
Aug 25, 2024
Merged

Net Billing: Credit expiry and same month credit application (Inflow/Outflow) #1200

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233a311
net billing: allow accrued net billing credits to expire at end of tr…
berg-michael Aug 7, 2024
db93f48
don't double count month excess credits
berg-michael Aug 9, 2024
7087104
Merge branch 'develop' of https://github.com/NREL/ssc into iowa_billing
brtietz Aug 23, 2024
996b687
Add tests for new net billing checkboxes
brtietz Aug 23, 2024
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2 changes: 2 additions & 0 deletions shared/lib_utility_rate_equations.h
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Original file line number Diff line number Diff line change
Expand Up @@ -144,6 +144,8 @@ class rate_data {
bool nm_credits_w_rollover; // rate option 0 only
int net_metering_credit_month;
double nm_credit_sell_rate;
bool nb_credit_expire; // For billing regimes in which credit can be accumulated and spent during a calendar year but cannot be redeemed for cash at the end of the year.
bool nb_apply_credit_current_month;

rate_data();
rate_data(const rate_data& tmp);
Expand Down
94 changes: 54 additions & 40 deletions ssc/cmod_utilityrate5.cpp
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Expand Up @@ -415,6 +415,8 @@ void rate_setup::setup(var_table* vt, int num_recs_yearly, size_t nyears, rate_d
rate.enable_nm = (metering_option == 0 || metering_option == 1);
rate.nm_credits_w_rollover = (vt->as_integer("ur_metering_option") == 0);
rate.net_metering_credit_month = (int)vt->as_number("ur_nm_credit_month");
rate.nb_credit_expire = vt->as_boolean("ur_nb_credit_expire");
rate.nb_apply_credit_current_month = vt->as_boolean("ur_nb_apply_credit_current_month");
rate.nm_credit_sell_rate = vt->as_number("ur_nm_yearend_sell_rate");

ssc_number_t* ratchet_matrix = NULL; ssc_number_t* bd_tou_matrix = NULL;
Expand Down Expand Up @@ -2235,6 +2237,10 @@ class cm_utilityrate5 : public compute_module
//int metering_option = as_integer("ur_metering_option");
bool excess_monthly_dollars = (as_integer("ur_metering_option") == 3);
int excess_dollars_credit_month = (int)as_number("ur_nm_credit_month");
// Do our credits expire at the end of year
bool nb_credit_expire = as_boolean("ur_nb_credit_expire");
// Do we wish to apply our credits in the month they are earned
bool nb_apply_credit_current_month = as_boolean("ur_nb_apply_credit_current_month");

rate.tou_demand_single_peak = (as_integer("TOU_demand_single_peak") == 1);

Expand Down Expand Up @@ -2321,48 +2327,48 @@ class cm_utilityrate5 : public compute_module
// main loop
c = 0; // hourly count
// process one timestep at a time
for (m = 0; m < 12; m++)
for (m = 0; m < 12; m++) // for each month
{
ur_month& curr_month = rate.m_month[m];
monthly_surplus_energy = 0;
ur_month& curr_month = rate.m_month[m];
monthly_surplus_energy = 0;
monthly_deficit_energy = 0;
if (ur_ec_hourly_acc_period == 1) {
surplus_tier = 0;
deficit_tier = 0;
}

for (d = 0; d<util::nday[m]; d++)
for (d = 0; d<util::nday[m]; d++) // for each day
{
daily_surplus_energy = 0;
daily_deficit_energy = 0;
if (ur_ec_hourly_acc_period == 2) {
if (ur_ec_hourly_acc_period == 2) { // This will never happen because we set it to 1 above
surplus_tier = 0;
deficit_tier = 0;
}
for (h = 0; h<24; h++)
for (h = 0; h<24; h++) // for each hour
{
for (s = 0; s < (int)steps_per_hour && c < (int)m_num_rec_yearly; s++)
for (s = 0; s < (int)steps_per_hour && c < (int)m_num_rec_yearly; s++) // as far as I can tell given an hour usage profile, etc, this should be a single iteration
{
// energy charge
if (ec_enabled)
if (ec_enabled) // Also always true, "energy charge enabled",
{
int row = rate.get_tou_row(c, m);

step_surplus_energy = 0.0;
step_deficit_energy = 0.0;

if (e_in[c] >= 0.0)
if (e_in[c] >= 0.0) // If we have money earned
{ // calculate income or credit
e_upper = curr_month.ec_tou_ub.at(row, surplus_tier); // Have to check this each step to swap between surplus and deficit
monthly_surplus_energy += e_in[c];
daily_surplus_energy += e_in[c];

// base period charge on units specified
ssc_number_t energy_surplus = e_in[c];
ssc_number_t energy_surplus = e_in[c];
ssc_number_t cumulative_energy = e_in[c];
if (ur_ec_hourly_acc_period == 1)
if (ur_ec_hourly_acc_period == 1) // Always 1
cumulative_energy = monthly_surplus_energy;
else if (ur_ec_hourly_acc_period == 2)
else if (ur_ec_hourly_acc_period == 2) // Never taken
cumulative_energy = daily_surplus_energy;


Expand All @@ -2381,15 +2387,15 @@ class cm_utilityrate5 : public compute_module
}

// Fall back to TOU rates if m_ec_ts_sell_rate.size() is too small
if (tier_credit == 0) {
if (cumulative_energy <= e_upper) {
tier_energy = energy_surplus;
if (tier_credit == 0) { // So AFAICT this is to make sure we don't compute both time step and TOU. Maybe better as an else?
if (cumulative_energy <= e_upper) { // If we are within the max usage for the tier, then it's a simple multiply
tier_energy = energy_surplus; // of our usage with that rate and the escalator
sr = curr_month.ec_tou_sr.at(row, surplus_tier);

tier_credit = tier_energy * sr * rate_esc;
curr_month.ec_energy_surplus.at(row, surplus_tier) += (ssc_number_t)tier_energy;
}
else {
else { // Otherwise, we need to handle that the electricity is being sold at different rates
bool break_tier_loop = false;
while (cumulative_energy > e_upper) {
step_surplus_energy = energy_surplus - (cumulative_energy - e_upper); // Subtract amount above the tier to find amount in this tier
Expand Down Expand Up @@ -2428,7 +2434,7 @@ class cm_utilityrate5 : public compute_module
credit_amt = tier_credit;


if (excess_monthly_dollars)
if (excess_monthly_dollars) // NB with carryover to next month
{
monthly_cumulative_excess_dollars[m] += credit_amt;
}
Expand All @@ -2447,10 +2453,10 @@ class cm_utilityrate5 : public compute_module
}
}
}
else
else // Same calc but with spending money
{ // calculate payment or charge
e_upper = curr_month.ec_tou_ub.at(row, deficit_tier); // Have to check this each step to swap between surplus and deficit
monthly_deficit_energy -= e_in[c];
monthly_deficit_energy -= e_in[c];
daily_deficit_energy -= e_in[c];
double charge_amt = 0;
double energy_deficit = -e_in[c];
Expand Down Expand Up @@ -2555,38 +2561,44 @@ class cm_utilityrate5 : public compute_module

// Calculate monthly bill (before minimums and fixed charges) and excess kwhs and rollover

monthly_bill[m] = monthly_ec_charges[m] + rate.monthly_dc_fixed[m] + rate.monthly_dc_tou[m];
monthly_bill[m] = monthly_ec_charges[m] + rate.monthly_dc_fixed[m] + rate.monthly_dc_tou[m]; // This code seems unnecessary, it is repeated verbatim below

excess_dollars_earned[m] = monthly_cumulative_excess_dollars[m];


ssc_number_t dollars_applied = 0;
// apply previous month rollover kwhs
if (excess_monthly_dollars)
if (excess_monthly_dollars) // If in net billing with carrover to next month
{
// Overwrite this to include the current month's charges
monthly_ec_charges_gross[m] = monthly_ec_charges[m];
if (m == 0 && excess_dollars_credit_month != 11) {
monthly_ec_charges[m] -= prev_excess_dollars;
if (m == 0 && excess_dollars_credit_month != 11) { // If start of the year and the rollover month not december
monthly_ec_charges[m] -= prev_excess_dollars; // prev_excess dollars is the value of the credit coming in from last year
payment[c - 1] -= prev_excess_dollars;
dollars_applied += prev_excess_dollars;
}
else if (m > 0 && m != excess_dollars_credit_month + 1)
else if (m > 0 && m != excess_dollars_credit_month + 1) // If during the middle of the year and the rollover month not the prior month
{
monthly_ec_charges[m] -= monthly_cumulative_excess_dollars[m - 1];
payment[c - 1] -= monthly_cumulative_excess_dollars[m - 1];
dollars_applied += monthly_cumulative_excess_dollars[m - 1];
}
if (nb_apply_credit_current_month) {
monthly_ec_charges[m] -= monthly_cumulative_excess_dollars[m];
payment[c - 1] -= monthly_cumulative_excess_dollars[m];
dollars_applied += monthly_cumulative_excess_dollars[m];
monthly_cumulative_excess_dollars[m] = 0;
}
// Rollover credits at end of true-up period are applied after annual minimums below this section

if (monthly_ec_charges[m] < 0)
if (monthly_ec_charges[m] < 0) // If this brings the monthly energy charges negative, then
{
payment[c - 1] -= monthly_ec_charges[m];
dollars_applied += monthly_ec_charges[m];
monthly_cumulative_excess_dollars[m] -= monthly_ec_charges[m];
payment[c - 1] -= monthly_ec_charges[m]; // Add the magnitude of the negative amount to the last hour of the month
dollars_applied += monthly_ec_charges[m];// Subtract the magnitude of the negative amount from the dollars applied
monthly_cumulative_excess_dollars[m] -= monthly_ec_charges[m]; //add in the magnitude of the negative amount to the cumulative excess for this month
monthly_ec_charges[m] = 0;
}

// I'm pretty sure this branch can't be taken.
if (monthly_ec_charges_gross[m] < dollars_applied) dollars_applied = monthly_ec_charges_gross[m];
net_billing_credits[m] = dollars_applied;
}
Expand Down Expand Up @@ -2645,17 +2657,19 @@ class cm_utilityrate5 : public compute_module
}
}
}

if (m == excess_dollars_credit_month)
{
// apply annual rollovers AFTER minimum calculations
if (excess_monthly_dollars && (monthly_cumulative_excess_dollars[m] > 0))
{
income[c] += monthly_cumulative_excess_dollars[m];
monthly_bill[m] -= monthly_cumulative_excess_dollars[m];
monthly_true_up_credits[m] = monthly_cumulative_excess_dollars[m];
}
}
if (!nb_credit_expire)
{
if (m == excess_dollars_credit_month)
{
// apply annual rollovers AFTER minimum calculations
if (excess_monthly_dollars && (monthly_cumulative_excess_dollars[m] > 0))
{
income[c] += monthly_cumulative_excess_dollars[m];
monthly_bill[m] -= monthly_cumulative_excess_dollars[m];
monthly_true_up_credits[m] = monthly_cumulative_excess_dollars[m];
}
}
}
monthly_bill[m] += monthly_fixed_charges[m] + monthly_minimum_charges[m];
}
revenue[c] = income[c] - payment[c];
Expand Down
3 changes: 2 additions & 1 deletion ssc/common.cpp
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Expand Up @@ -1010,7 +1010,8 @@ var_info vtab_utility_rate_common[] = {
{ SSC_INPUT, SSC_NUMBER, "ur_nm_credit_month", "Month of year end payout (true-up)", "mn", "", "Electricity Rates", "?=11", "INTEGER,MIN=0,MAX=11", "" },
{ SSC_INPUT, SSC_NUMBER, "ur_nm_credit_rollover", "Apply net metering true-up credits to future bills", "0/1", "0=disable,1=enable", "Electricity Rates", "?=0", "INTEGER,MIN=0,MAX=1", "" },
{ SSC_INPUT, SSC_NUMBER, "ur_monthly_fixed_charge", "Monthly fixed charge", "$", "", "Electricity Rates", "?=0.0", "", "" },

{ SSC_INPUT, SSC_NUMBER, "ur_nb_credit_expire", "Credit is lost upon end of year ", "0/1", "0=disable,1=enable", "Electricity Rates", "?=0", "INTEGER,MIN=0,MAX=1", "" },
{ SSC_INPUT, SSC_NUMBER, "ur_nb_apply_credit_current_month", "Apply earned credits to balance before rolling over excess ", "0/1", "0=disable,1=enable", "Electricity Rates", "?=0", "INTEGER,MIN=0,MAX=1", "" },

// optional input that allows sell rates to be overridden with buy rates - defaults to not override
{ SSC_INPUT, SSC_NUMBER, "ur_sell_eq_buy", "Set sell rate equal to buy rate", "0/1", "Optional override", "Electricity Rates", "?=0", "BOOLEAN", "" },
Expand Down
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