diff --git a/README.md b/README.md
index 787a37c..5d4b7c0 100644
--- a/README.md
+++ b/README.md
@@ -25,11 +25,12 @@ Currently the tools use the CEC, in most cases this will match the NEC, but some
 
 # Future Features
 
-- [x] Web app (this is started at [Digital Power Systems Toolbox](http://toolbox.digitalpowersystems.net))
+- [x] Web app (this is started at [Digital Power Systems Toolbox](http://toolbox.digitalpowersystems.net)
 - [x] Installable package [The first releases are here](https://git.jmkengineering.com/JMK_Engineering_Inc/JMKTools/releases)
 - [ ] Add NEC to the calculations
-- [ ] Re-do and add PV functions to the package.
+- [x] Re-do and add PV functions to the package.
 - [ ] Detailed documentation (the source is started in this repo)
 - [ ] Electrical Safety Calculations
 - [ ] Basic Load flow tools
-- [ ] Basic Shortcircuit tools
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+- [ ] Basic Short circuit tools
+- [ ] Continue developing the DPS Toolbox
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diff --git a/src/jmktools/__init__.py b/src/jmktools/__init__.py
index 84e0c09..e6421ee 100644
--- a/src/jmktools/__init__.py
+++ b/src/jmktools/__init__.py
@@ -1,6 +1,7 @@
 from .circuits import *
 from .general import *
 from .grounding import *
+from .pvsolar import *
 from .tables import *
 
 def main() -> None:
diff --git a/src/jmktools/pvsolar.py b/src/jmktools/pvsolar.py
new file mode 100644
index 0000000..ac18660
--- /dev/null
+++ b/src/jmktools/pvsolar.py
@@ -0,0 +1,62 @@
+'''
+JMK Engineering Inc. Python Tools
+by: Jeff MacKinnon
+
+email: jeff@jmkengineering.com
+
+PV Design functions
+
+'''
+
+def temp_adj_Voc(Voc,temp,beta=-0.5,STCtemp = 25):
+
+    ''' 
+        The Voc of a panel will increase as the temperature decreases.
+        The datasheet Voc is typically at STC, or 25C. As the temperature decreases this Voc needs to be adjusted.
+        This adjustment is linear based on the beta value with the units %/C.
+        This beta value will be shown as a negative indicating that as the temperature increases, then the Voc will decrease.
+        This Voc decrease results in derating of power during temperature above 25C.
+
+        Voc = The STC panel open circuit voltage
+        temp = The min or max temperature for the PV plant.
+        beta = The panel temperature coefficient. default -0.5%/C, typical values will range from -0.2 to -0.45.
+
+        The adjusted Voc is Voc minus the voltage shift. When the outside temperature is above the STC value then the Vocadj will be lower.
+    '''
+
+    tempadj = STCtemp - temp #-
+
+    percent_shift = tempadj * beta/100 #+
+
+    
+    volt_shift = Voc * percent_shift
+
+    Vocadj = Voc - volt_shift # The voltage adjust is the 
+
+    return Vocadj
+
+
+def panels_per_string(Vmax,Voc,beta=-0.5,temp = 25,STCtemp = 25):
+
+    '''
+        This function calculates the maximum number of panels that a string can have.
+        It will automatically calculate the temperature shifted number when beta and temp are given.
+
+    '''
+    Vocadj = temp_adj_Voc(Voc, temp,beta, STCtemp = 25)
+
+    panels_per_string_max = Vmax // Vocadj
+
+    return int(panels_per_string_max)
+
+def voltage_per_string(panels,Voc,beta=-0.5,temp = 25,STCtemp = 25):
+    '''
+        This function calculates the temperature adjusted string voltage based on the number of panels, open-circuit voltage (Voc).
+        By default it assumes a beta of -0.5, tem of 25C and a tested STCtemp of 25C.
+    '''
+
+    vocadj = temp_adj_Voc(Voc, temp,beta, STCtemp = 25)
+
+    voltage = vocadj * panels
+
+    return round(voltage,4)
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