VE6FI Amateur Radio
VE6fi is now 100 percent solar powered. We have no ties to any grid services. We are not connected to the electrical grid, the natural gas grid or the telephone network. We are not even connected by a road.
The solar panels shown here are 30 volt 7.5 amp panels. At the moment we connect seven of them in series for 210 volts. We plan to connect them as eight panels for 240 volts. We connect 16 of them in series for a set. This gives us +240 and a -240 rail which matches our batteries and UPS. The panels have an unrestricted view of the sky and are set at 30 degrees off of vertical to optimize them for winter operation. The panels deliver around 7.5 KW under sunny conditions and around 4 KW under cloudy conditions.
Below is shown the mounting for the solar panels. We used 24 inch tower sections that we had in stock which are held in position with four screw in anchors which are four feet long. The carpenter who put this package together was Evan, Ve6fi.
Below we are unloading a 40 KW UPS into our power module. We have real stories to tell about our purchase of UPS from the government auction. You can read more about them here.
Below is another UPS that we purchased. This one is a 3.3 KVA unit.
Read more about this UPS adventure here
Batteries - well they said the racks would support 2500 pounds per shelf. As you can see we had to add additional bracing so in reality they will support 2500 pounds over four shelves. These are located in our heated power module.
Below is our 'Charge Controller' which we custom designed. We did not want to use the traditionally PWM (pulse width modulation) method of controlling the charge on the batteries because of the noise they produce in the RF spectrum. In our amateur radio operation we wanted to receive low level signals and not have that masked over by PWM noise. Ian Burn ve6ob, our resident PIC designer took on the task and provided us with a noise free versatile controller. In the display below the battery voltage is shown as 223 volts. The level L3 of 221 is set as the level where we put extra load (heaters) on the UPS so that the battery charging current decreases as the voltage rises. As the voltage rises to the next level of L2=230 volts we had more heaters on the UPS to again reduce the current charging the batteries. If the level increases to 235 volts which would be 2.45 volts/cell we disconnect the solar panels. The settings on the display can be changed by another menu. Also the amount of time that the external loads or disconnects are active is selected by pin jumpers inside the cabinet. The unit is powered by a separate DC battery. Another nice feature of this controller is that it has a log built into it so that we can read how many times the different thresholds have been reached. When we turn the switch to summer we drop one set of panels or 3.75 KW as we just do not need the extra energy. This is when grid tie would come in handy. This controller works great.
The picture below on the left is the inside of the Charge Controller. It uses one main programmed microchip (PIC) for the main program and four smaller PICs for the timers. the box on the right is the relay interface box. The charge controllers drives the small relays that control larger relays which are in other locations. Note that we use ferrites quit liberally just in case there is some noise trying to sneak out. The relay interface box includes a fail save comparator such that if we loose the Charge Controller for any reason then when the voltage goes up to 250 volts DC the solar panels will be locked out until a manual reset is done at the site.
Below is the picture of the insides of the relay interface box. We sample the battery voltage of 240 volts and reduce it down to a zero to five volt level. The 250 volt comparator circuit is on the right.
The third UPS that we purchased was a 8 KVA APC unit and that is the unit we are using. However it did not have an internal transformer and just provided 240 volts two wire out. The transformers below convert the 240 volt 2 wire to a 240/120 volt 3 wire circuit that we require to feed our standard AC distribution boxes. See more on the UPS adventure here