Index: openacs-4/packages/accounts-finance/tcl/energy-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/accounts-finance/tcl/energy-procs.tcl,v
diff -u
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ openacs-4/packages/accounts-finance/tcl/energy-procs.tcl	28 May 2010 06:35:03 -0000	1.1
@@ -0,0 +1,39 @@
+ad_library {
+
+    energy based routines used for modeling cashflows etc
+    @creation-date 27 May 2010
+    @cvs-id $Id:
+}
+
+ad_proc -public acc_fin::energy_output {
+    base_system_performance
+    peak_power_output
+    annual_degredation
+    year
+    intervals_per_year
+} {
+    returns the system energy output within an interval
+    Unit returned is in kWh if these units are used:
+    base_system_performance (hours of available peak energy / year or kWh/kW )
+    peak_power_output ( kW )
+    annual_degredation ( percent expressed as a decimal number )  10% is 0.1
+} {
+    set energy_output [expr { $base_system_performance * $peak_power_output * ( 1. - (( $year - 1. ) * $annual_degredation ) ) / double($periods_per_year) } ]
+    return $energy_output
+} 
+
+ad_proc -public acc_fin::energy_ppa_revenue {
+    energy_output
+    ppa_rate
+    ppa_escalation
+    year
+} {
+    returns the revenue amount from selling the energy on a purchase power agreement (PPA) during the year specified. 
+    Unit returned is in currency of ppa_rate if these units are used:
+    energy_output (kWh)
+    ppa_rate (currency /kWh)
+    ppa_escalation ( percent expressed as a decimal number) 10% is 0.1
+} {
+    set revenue [expr { $energy_output * $ppa_rate * pow( 1. + $ppa_escalation , $year - 1. ) } ]
+    return $revenue
+} 
Index: openacs-4/packages/accounts-finance/tcl/modeling-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/accounts-finance/tcl/modeling-procs.tcl,v
diff -u -r1.3 -r1.4
--- openacs-4/packages/accounts-finance/tcl/modeling-procs.tcl	27 May 2010 20:21:34 -0000	1.3
+++ openacs-4/packages/accounts-finance/tcl/modeling-procs.tcl	28 May 2010 06:35:03 -0000	1.4
@@ -35,6 +35,17 @@
     return $sign
 }
 
+ad_proc -public acc_fin::inflation_factor {
+    annual_inflation_rate
+    intervals_per_year
+    year
+} {
+    Returns the factor to apply to a value to adjust for inflation.
+    Assumes inflationary factors occur once per year at end of year.
+} {
+    set inflationary_factor [expr { pow ( 1. + $annual_inflation_rate / double($intervals_per_year) , $year - 1. ) } ]
+}
+
 ad_proc -private acc_fin::template_model { 
     template_number
 } {
@@ -621,6 +632,20 @@
 }
 
 
-# create proc gl_tx that accepts pairs of account debit/credit, where debits = credits
-# create procs to mimmic AR/Transaction, AP/transaction, and other common transactions to reduce model complexity.
+
+# create procs for?
+# AR/
+# AR/sale  1000 x, 1200 -x, 1200 x, 4000 x
+# AP/vendor payment cash  1000 -x ,2100 x, 2100 -x, 5000 x
+# ..let's wait until we know if this is necessary. gl_tx seems adequate for now.
+
+# system energy output 
+# revenue from energy output
+
+# create procs to maintain a debt via interation (add interest, add payment, adjust balance for each)
+# monitor for payback period during iteration
+# 
 # create proce that shows balance sheet etc for any period or difference between two or more periods
+# proc profitability_index (PV of future cashflows over project life / initial investment)
+
+