Added solar controller blog post

input/blog/2018/2018_10_06_solar.md

@@ -0,0 +1,88 @@
+title: Blog
+post: Photovoltaics Sun-Direction Controller
+date: 2018-10-06
+comments: true
+---
+
+## {{ page["post"] }}
+<!--%
+from datetime import datetime
+date = datetime.strptime(page["date"], "%Y-%m-%d").strftime("%B %d, %Y")
+print "*Posted at %s.*" % date
+%-->
+
+For about 30 years my Grandfather has been using Photovoltaics to generate electricity.
+First for his small electric car that stored the energy in dozens of 12V lead batteries, later for feeding into the general electrical grid with an inverter.
+
+The solar panels are mounted on a mast, about 5m high, in the garden.
+They can be rotated to follow the sun. A simple (pre-bought) PCB uses two LDRs to sense
+the suns direction in relation to the solar panels, moving the motor accordingly to balance their signals.
+
+Last week I had to take a look at this system because the solar panels were no longer rotating.
+Luckily, only the old Bosch 12V 2.6A power supply for the logic circuit and the motor was broken.
+I simply replaced it with a cheap wall-wart.
+
+<div class="lightgallery">
+    <a href="img/solar_1.jpg">
+        <img src="img/solar_1_small.jpg" alt="Overview of controller box">
+    </a>
+    <a href="img/solar_2.jpg">
+        <img src="img/solar_2_small.jpg" alt="Closeup of PCB">
+    </a>
+    <a href="img/solar_3.jpg">
+        <img src="img/solar_3_small.jpg" alt="All electonics on the mast">
+    </a>
+    <a href="img/solar_4.jpg">
+        <img src="img/solar_4_small.jpg" alt="Full mast view">
+    </a>
+    <a href="img/solar_5.jpg">
+        <img src="img/solar_5_small.jpg" alt="Closeup of rubber clutch">
+    </a>
+    <a href="img/solar_6.jpg">
+        <img src="img/solar_6_small.jpg" alt="Motor and gearbox">
+    </a>
+    <a href="img/solar_7.jpg">
+        <img src="img/solar_7_small.jpg" alt="Endstop switches and mechanical lock">
+    </a>
+    <a href="img/solar_8.jpg">
+        <img src="img/solar_8_small.jpg" alt="Closeup of endstop switches">
+    </a>
+    <a href="img/solar_9.jpg">
+        <img src="img/solar_9_small.jpg" alt="Full photovoltaics mast">
+    </a>
+    <a href="img/solar_10.jpg">
+        <img src="img/solar_10_small.jpg" alt="Photovoltaics inverter">
+    </a>
+    <a href="img/solar_11.jpg">
+        <img src="img/solar_11_small.jpg" alt="Power Supply for controller">
+    </a>
+</div>
+
+I was already thinking about replacing the whole circuit with an ESP32 or something similar.
+But it still seems to work fine, so this plan is on hold for now.
+
+Below you can find the original description as well as the schematic for the logic circuit.
+
+<div class="lightgallery">
+    <a href="img/solar_12.png">
+        <img src="img/solar_12_small.png" alt="Description, page 1">
+    </a>
+    <a href="img/solar_13.png">
+        <img src="img/solar_13_small.png" alt="Descrtiption, page 2">
+    </a>
+    <a href="img/solar_15.png">
+        <img src="img/solar_15_small.png" alt="Schematics">
+    </a>
+    <a href="img/solar_14.png">
+        <img src="img/solar_14_small.png" alt="Overview">
+    </a>
+</div>
+
+My Grandfather has modified this circuit.
+In its original form it was only using a third LDR on the PCB to move toward the east-endstop at night, to prepare for the next day-cycle.
+In cloudy weather, this has been causing problems because in the morning the light levels were not high enough for the motor to move.
+Then, at noon, the sun was shining brightly again but was already too far westwards to be sensed by the LDRs.
+So my Grandfather installed a time-switch in the cellar to output a signal everyday at noon.
+He added some circuitry to move the motor to a new south-endstop (rather a mid-stop) to avoid the problem described above.
+I was not yet able to find his notes about these modifications, and I was not motivated enough to reverse-engineer them, so maybe I will deliver in future on that...
+