diff --git a/docs/sphinx/source/whatsnew.rst b/docs/sphinx/source/whatsnew.rst
index 9c0089047c..dadc0ecaef 100644
--- a/docs/sphinx/source/whatsnew.rst
+++ b/docs/sphinx/source/whatsnew.rst
@@ -6,6 +6,7 @@ What's New
 
 These are new features and improvements of note in each release.
 
+.. include:: whatsnew/v0.2.2.txt
 .. include:: whatsnew/v0.2.1.txt
 .. include:: whatsnew/v0.2.0.txt
 .. include:: whatsnew/v0.1.0.txt
diff --git a/docs/sphinx/source/whatsnew/v0.2.2.txt b/docs/sphinx/source/whatsnew/v0.2.2.txt
new file mode 100644
index 0000000000..f3d9ea2040
--- /dev/null
+++ b/docs/sphinx/source/whatsnew/v0.2.2.txt
@@ -0,0 +1,27 @@
+.. _whatsnew_0220:
+
+v0.2.2 (November, 2015)
+-----------------------
+
+This is a minor release from 0.2.1.
+We recommend that all users upgrade to this version.
+
+Enhancements
+~~~~~~~~~~~~
+
+* Adds Python 3.5 compatibility (:issue:`87`)
+
+
+Bug fixes
+~~~~~~~~~
+
+* Uses the ``logging`` module properly by replacing ``format``
+  calls with ``args``. This results in a 5x speed increase for
+  ``tracking.singleaxis`` (:issue:`89`).
+* Adds a link to the 2015 PVSC paper (:issue:`81`)
+
+Contributors
+~~~~~~~~~~~~
+
+* Will Holmgren
+* dacoex
diff --git a/pvlib/atmosphere.py b/pvlib/atmosphere.py
index 4e6b4ae624..0ba96bf855 100644
--- a/pvlib/atmosphere.py
+++ b/pvlib/atmosphere.py
@@ -237,8 +237,8 @@ def relativeairmass(zenith, model='kastenyoung1989'):
         AM = ( 1.0 / (np.cos(zenith_rad) +
             0.00176759*(z)*((94.37515 - z) ** - 1.21563)) )
     else:
-        pvl_logger.warning("{} is not a valid model type for relative airmass. The 'kastenyoung1989' model was used."
-                           .format(model))
+        pvl_logger.warning("%s is not a valid model type for relative airmass. The 'kastenyoung1989' model was used.",
+                           model)
         AM = ( 1.0 / (np.cos(zenith_rad) +
             0.50572*(((6.07995 + (90 - z)) ** - 1.6364))) )
     
diff --git a/pvlib/clearsky.py b/pvlib/clearsky.py
index f1c9fe0f2f..cd16284d21 100644
--- a/pvlib/clearsky.py
+++ b/pvlib/clearsky.py
@@ -135,7 +135,7 @@ def ineichen(time, location, linke_turbidity=None,
         
         # consider putting this code at module level
         this_path = os.path.dirname(os.path.abspath(__file__))
-        logger.debug('this_path={}'.format(this_path))
+        logger.debug('this_path=%s', this_path)
         
         mat = scipy.io.loadmat(os.path.join(this_path, 'data', 'LinkeTurbidities.mat'))
         linke_turbidity = mat['LinkeTurbidity']
@@ -153,7 +153,7 @@ def ineichen(time, location, linke_turbidity=None,
             LT = pd.DataFrame(time.month, index=time)
             LT = LT.apply(ApplyMonth, axis=1)
         TL = LT / 20.
-        logger.info('using TL=\n{}'.format(TL))
+        logger.info('using TL=\n%s', TL)
     else:
         TL = linke_turbidity
 
@@ -170,7 +170,7 @@ def ineichen(time, location, linke_turbidity=None,
     fh2 = np.exp(-location.altitude/1250.)
     cg1 = 5.09e-05 * location.altitude + 0.868
     cg2 = 3.92e-05 * location.altitude + 0.0387
-    logger.debug('fh1={}, fh2={}, cg1={}, cg2={}'.format(fh1, fh2, cg1, cg2))
+    logger.debug('fh1=%s, fh2=%s, cg1=%s, cg2=%s', fh1, fh2, cg1, cg2)
 
     #  Dan's note on the TL correction: By my reading of the publication on
     #  pages 151-157, Ineichen and Perez introduce (among other things) three
@@ -203,7 +203,7 @@ def ineichen(time, location, linke_turbidity=None,
     # BncI == "normal beam clear sky radiation"
     b = 0.664 + 0.163/fh1
     BncI = b * I0 * np.exp( -0.09 * AMabsolute * (TL - 1) )
-    logger.debug('b={}'.format(b))
+    logger.debug('b=%s', b)
     
     # "empirical correction" SE 73, 157 & SE 73, 312.
     BncI_2 = ( clearsky_GHI *
diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 7fc7d6b92d..4c03e16ba5 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -513,8 +513,8 @@ def grounddiffuse(surface_tilt, ghi, albedo=.25, surface_type=None):
 
     if surface_type is not None:
         albedo = SURFACE_ALBEDOS[surface_type]
-        pvl_logger.info('surface_type={} mapped to albedo={}'
-                        .format(surface_type, albedo))
+        pvl_logger.info('surface_type=%s mapped to albedo=%s',
+                        surface_type, albedo)
 
     diffuse_irrad = ghi * albedo * (1 - np.cos(np.radians(surface_tilt))) * 0.5
 
@@ -1489,7 +1489,7 @@ def dirint(ghi, zenith, times, pressure=101325, use_delta_kt_prime=True,
     kt_prime = kt / (1.031 * np.exp(-1.4/(0.9+9.4/airmass)) + 0.1)
     kt_prime[kt_prime > 0.82] = 0.82 # From SRRL code. consider np.NaN
     kt_prime.fillna(0, inplace=True)
-    pvl_logger.debug('kt_prime:\n{}'.format(kt_prime))
+    pvl_logger.debug('kt_prime:\n%s', kt_prime)
     
     # wholmgren: 
     # the use_delta_kt_prime statement is a port of the MATLAB code.
@@ -1519,7 +1519,7 @@ def dirint(ghi, zenith, times, pressure=101325, use_delta_kt_prime=True,
     kt_prime_bin[(kt_prime>=0.56) & (kt_prime<0.7)] = 4
     kt_prime_bin[(kt_prime>=0.7) & (kt_prime<0.8)] = 5
     kt_prime_bin[(kt_prime>=0.8) & (kt_prime<=1)] = 6
-    pvl_logger.debug('kt_prime_bin:\n{}'.format(kt_prime_bin))
+    pvl_logger.debug('kt_prime_bin:\n%s', kt_prime_bin)
     
     # Create zenith angle bins
     zenith_bin = pd.Series(index=times)
@@ -1529,7 +1529,7 @@ def dirint(ghi, zenith, times, pressure=101325, use_delta_kt_prime=True,
     zenith_bin[(zenith>=55) & (zenith<70)] = 4
     zenith_bin[(zenith>=70) & (zenith<80)] = 5
     zenith_bin[(zenith>=80)] = 6
-    pvl_logger.debug('zenith_bin:\n{}'.format(zenith_bin))
+    pvl_logger.debug('zenith_bin:\n%s', zenith_bin)
     
     # Create the bins for w based on dew point temperature
     w_bin = pd.Series(index=times)
@@ -1538,7 +1538,7 @@ def dirint(ghi, zenith, times, pressure=101325, use_delta_kt_prime=True,
     w_bin[(w>=2) & (w<3)] = 3
     w_bin[(w>=3)] = 4
     w_bin[(w == -1)] = 5
-    pvl_logger.debug('w_bin:\n{}'.format(w_bin))
+    pvl_logger.debug('w_bin:\n%s', w_bin)
 
     # Create delta_kt_prime binning.
     delta_kt_prime_bin = pd.Series(index=times)
@@ -1549,7 +1549,7 @@ def dirint(ghi, zenith, times, pressure=101325, use_delta_kt_prime=True,
     delta_kt_prime_bin[(delta_kt_prime>=0.15) & (delta_kt_prime<0.3)] = 5
     delta_kt_prime_bin[(delta_kt_prime>=0.3) & (delta_kt_prime<=1)] = 6
     delta_kt_prime_bin[delta_kt_prime == -1] = 7
-    pvl_logger.debug('delta_kt_prime_bin:\n{}'.format(delta_kt_prime_bin))
+    pvl_logger.debug('delta_kt_prime_bin:\n%s', delta_kt_prime_bin)
     
     # subtract 1 to account for difference between MATLAB-style bin
     # assignment and Python-style array lookup.
diff --git a/pvlib/pvsystem.py b/pvlib/pvsystem.py
index c055b2d8b2..66bff02a1f 100644
--- a/pvlib/pvsystem.py
+++ b/pvlib/pvsystem.py
@@ -547,7 +547,7 @@ def retrieve_sam(name=None, samfile=None):
         raise ValueError('must supply name or samfile')
 
     if samfile is None:
-        pvl_logger.info('retrieving {} from {}'.format(name, url))
+        pvl_logger.info('retrieving %s from %s', name, url)
         response = urlopen(url)
         csvdata = io.StringIO(response.read().decode(errors='ignore'))
     elif samfile == 'select':
@@ -1115,7 +1115,6 @@ def i_from_v(resistance_shunt, resistance_series, nNsVth, voltage,
             np.exp( Rsh*(Rs*(IL+I0)+V) / (nNsVth*(Rs+Rsh)) ) /
             (nNsVth*(Rs + Rsh)) )
     lambertwterm = lambertw(argW)
-    pvl_logger.debug('argW: {}, lambertwterm{}'.format(argW, lambertwterm))
 
     # Eqn. 4 in Jain and Kapoor, 2004
     I = -V/(Rs + Rsh) - (nNsVth/Rs)*lambertwterm + Rsh*(IL + I0)/(Rs + Rsh)
diff --git a/pvlib/solarposition.py b/pvlib/solarposition.py
index 00eccd9cd1..1420cf92e8 100644
--- a/pvlib/solarposition.py
+++ b/pvlib/solarposition.py
@@ -536,8 +536,8 @@ def ephemeris(time, location, pressure=101325, temperature=12):
     # This helps a little bit:
     # http://www.cv.nrao.edu/~rfisher/Ephemerides/times.html
 
-    pvl_logger.debug('location={}, temperature={}, pressure={}'.format(
-        location, temperature, pressure))
+    pvl_logger.debug('location=%s, temperature=%s, pressure=%s',
+                     location, temperature, pressure)
 
     # the inversion of longitude is due to the fact that this code was
     # originally written for the convention that positive longitude were for
diff --git a/pvlib/spa.py b/pvlib/spa.py
index c7dac9fb17..b6a2962d8d 100644
--- a/pvlib/spa.py
+++ b/pvlib/spa.py
@@ -983,8 +983,8 @@ def solar_position_numba(unixtime, lat, lon, elev, pressure, temp, delta_t,
 
     if ulength < numthreads:
         pvl_logger.warning('The number of threads is more than the length of' +
-                           ' the time array. Only using {} threads.'.format(
-                               ulength))
+                           ' the time array. Only using %s threads.',
+                            ulength)
         numthreads = ulength
 
     if numthreads <= 1:
diff --git a/pvlib/tmy.py b/pvlib/tmy.py
index be70caa633..9e5d1678de 100644
--- a/pvlib/tmy.py
+++ b/pvlib/tmy.py
@@ -428,7 +428,7 @@ def _parsemeta_tmy2(columns, line):
     meta.append(float(rawmeta[10]))	
     
     meta_dict = dict(zip(columns.split(','),meta)) #Creates a dictionary of metadata
-    pvl_logger.debug('meta: {}'.format(meta_dict))
+    pvl_logger.debug('meta: %s', meta_dict)
     
     return meta_dict
 
diff --git a/pvlib/tools.py b/pvlib/tools.py
index 90b188b007..b1637a2fb7 100644
--- a/pvlib/tools.py
+++ b/pvlib/tools.py
@@ -130,8 +130,8 @@ def localize_to_utc(time, location):
             pvl_logger.debug('tz_convert to UTC')
         except TypeError:
             time_utc = time.tz_localize(location.tz).tz_convert('UTC')
-            pvl_logger.debug('tz_localize to {} and then tz_convert to UTC'
-                             .format(location.tz))
+            pvl_logger.debug('tz_localize to %s and then tz_convert to UTC',
+                             location.tz)
         
         
     return time_utc
diff --git a/pvlib/tracking.py b/pvlib/tracking.py
index 033b578084..0c49f17c2d 100644
--- a/pvlib/tracking.py
+++ b/pvlib/tracking.py
@@ -93,13 +93,12 @@ def singleaxis(apparent_zenith, apparent_azimuth,
     
     pvl_logger.debug('tracking.singleaxis')
     
-    pvl_logger.debug(('axis_tilt={}, axis_azimuth={}, max_angle={}, ' +
-                      'backtrack={}, gcr={:.3f}')
-                     .format(axis_tilt, axis_azimuth, max_angle, backtrack,
-                             gcr))
+    pvl_logger.debug('axis_tilt=%s, axis_azimuth=%s, max_angle=%s, ' +
+                     'backtrack=%s, gcr=%.3f',
+                     axis_tilt, axis_azimuth, max_angle, backtrack, gcr)
                              
-    pvl_logger.debug('\napparent_zenith=\n{}\napparent_azimuth=\n{}'
-                     .format(apparent_zenith.head(), apparent_azimuth.head()))
+    pvl_logger.debug('\napparent_zenith=\n%s\napparent_azimuth=\n%s',
+                     apparent_zenith.head(), apparent_azimuth.head())
     
     # MATLAB to Python conversion by 
     # Will Holmgren (@wholmgren), U. Arizona. March, 2015.
@@ -139,7 +138,7 @@ def singleaxis(apparent_zenith, apparent_azimuth,
     # wholmgren: strange to see axis_azimuth calculated differently from az,
     # (not that it matters, or at least it shouldn't...).
     axis_azimuth_south = axis_azimuth - 180
-    pvl_logger.debug('axis_azimuth_south={}'.format(axis_azimuth_south))
+    pvl_logger.debug('axis_azimuth_south=%s', axis_azimuth_south)
 
     # translate input array tilt angle axis_tilt to [1] coordinate system.
     
@@ -254,34 +253,34 @@ def singleaxis(apparent_zenith, apparent_azimuth,
     rot_x = np.array([[1, 0, 0], 
                       [0, cosd(-axis_tilt), -sind(-axis_tilt)], 
                       [0, sind(-axis_tilt), cosd(-axis_tilt)]])
-    pvl_logger.debug('rot_x=\n{}'.format(rot_x))
+    pvl_logger.debug('rot_x=\n%s', rot_x)
     
     # panel_norm_earth contains the normal vector
     # expressed in earth-surface coordinates
     # (z normal to surface, y aligned with tracker axis parallel to earth)
     panel_norm_earth = np.dot(rot_x, panel_norm).T
-    pvl_logger.debug('panel_norm_earth={}'.format(panel_norm_earth))
+    pvl_logger.debug('panel_norm_earth=%s', panel_norm_earth)
     
     # projection to plane tangent to earth surface,
     # in earth surface coordinates
     projected_normal = np.array([panel_norm_earth[:,0], 
                                  panel_norm_earth[:,1], 
                                  panel_norm_earth[:,2]*0]).T
-    pvl_logger.debug('projected_normal={}'.format(projected_normal))
+    pvl_logger.debug('projected_normal=%s', projected_normal)
     
     # calculate vector magnitudes
     panel_norm_earth_mag = np.sqrt(np.nansum(panel_norm_earth**2, axis=1))
     projected_normal_mag = np.sqrt(np.nansum(projected_normal**2, axis=1))
-    pvl_logger.debug('panel_norm_earth_mag={}, projected_normal_mag={}'
-                     .format(panel_norm_earth_mag, projected_normal_mag))
+    pvl_logger.debug('panel_norm_earth_mag=%s, projected_normal_mag=%s',
+                     panel_norm_earth_mag, projected_normal_mag)
 
     # renormalize the projected vector
     # avoid creating nan values.
     non_zeros = projected_normal_mag != 0
     projected_normal[non_zeros] = (projected_normal[non_zeros].T / 
                                    projected_normal_mag[non_zeros]).T
-    pvl_logger.debug('renormalized projected_normal={}'
-                     .format(projected_normal))
+    pvl_logger.debug('renormalized projected_normal=%s',
+                     projected_normal)
 
     # calculation of surface_azimuth
     # 1. Find the angle.