ring current by interpolatign</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">np</span><span class="o">.</span><span class="n">interp</span><span class="p">(</span><span class="n">pvsys</span><span class="o">.</span><span class="n">Vmp</span><span class="p">,</span> <span class="n">pvsys</span><span class="o">.</span><span class="n">pvstrs</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">Vstring</span><span class="p">,</span> 