Saturday, January 27, 2024

DIY Grid Down Solar Backup System

 Modern society, at least in the Western World, is highly dependent on cheap, available electricity. It is quite possible to live without it, the Amish community does just fine, but even they rely on electric to a small degree for their dairy farms and their retail outlets. It would be nearly impossible for a family in the West to go without it though, in reality. There are no ice ponds or ice warehouses to provide our ice boxes with cooling blocks of ice to keep our food and in many cases medicines from spoiling. One could buy just the food that they need for one day I suppose, but that would use a lot of time and a lot of gas to run to the store every day.

 There are plenty of folks that live off grid on homesteads and they use some electric, usually generated on site with a solar, wind, or micro-hydropower setup. They probably run their refrigerator on natural gas or propane, which anyone can do (though that comes with some daily chores to ensure the system is operating efficiently). 

 Short term, interior lighting can be done with batteries or oil lamps. Oil lamps were the way it was done for hundreds of years, but again, there are many daily chores involved with that such as wick trimming, chimney cleaning, pouring oil, cleaning the soot off the ceilings and walls, etc. Solar lights are effective and efficient but you have to take them outside during the day to charge and then bring them in to use.

 Anyway, I'm not here to give a lesson on homesteading. If you operate on the grid, like 99% of Americans do, then what you need is a short to medium term solution for when the grid goes down due to weather impacts, car accidents bringing down the lines, cyber attacks that shut down the grid, or intentional or unintentional damage to grid components such as sub-stations, transformers, transmission lines, or the power generating facilities. This interruption in power could be minutes, hours or days. Then what do you do? I have discussed that previously, a number of times, so we won't go into that here.

 This post is about how to build out a Do It Yourself backup power system incrementally as you have the funds to do it. As I have explained in previous posts, I started out with just a Marine Deep Discharge battery from my dad's boat hooked up to a 400 watt inverter to power some fans and recharge phones during a five-day black out. From that I upgraded to an Ecoflow Delta 1,300, which initially I was charging via a wall outlet and having it ready in case the power went out. I then hooked up 400 watts of solar panels to it so that I could recharge it if the power was out for an extended period. Luckily, that never happened. But we were ready. My next upgrade was to an Ecoflow Delta pro, which can hold 3,200 watt hours of power and can power up to 3,000 watts (though not for very long). I added a second battery, adding 3,200 more watt hours for a total of 7,400 watt hours. My latest upgrade is to add 1,280 watts of solar panels to this system.

 In a recent post, I described how I powered my home for 20 hours using the two Ecoflow units. At that time, I only had the 400 watts on solar panels hooked up and there was no sun for several days so there was no opportunity to see how well recharging would work. I was prepared to recharge both systems with my gas-powered generator if it was required.

 Over the past couple of days, when weather permitted, I have been building out the rack to hold my larger, 320 watt panels. I bought six, but initially I will only have four hooked up. Here is how that went.

 I did a good bit of research and decided to buy the EG4 BrightMount Solar Panel Ground Mount Rack Kit | 4 Panel Ground Mount | Adjustable Angle, by Signature Solar. I am not being paid by this company, it just happens to be the setup that I choose after considering what I wanted. Your situation will be different and another rack system might be more suitable. 

 I went with a ground mount for many reasons. In no particular order:

  • 1.  I can build it myself and save money. 
  • 2. I can move it if needed. 
  • 3. I can adjust the angle of the panels to compensate for the high sun in the summer and the low sun in winter. 
  • 4. Lastly, I can reach it to clear off snow and wash the panels.

 Most of the YouTube video reviews for the EG4 Bright Mount showed the rack mounted to the tops of either concrete or wood pillars. I didn't want such a permanent solution nor was it possible to do that kind of a build in the dead of winter; my ground is frozen. So I went with a timber platform, shown below.


 

I used 6x6x8 treated timbers, cut to four foot length. These are tied together with 2x6x12 with four inch construction screws. This weighs over two hundred pounds. Everything is square but the platform is not level yet.

 

The EG4 rack came very well boxed. All the hardware was in individual bags by type of connector. There were no damages. It only requires three tools to assemble the parts into their major components; two different Allen (Hex) wrenches and a 1/2 inch crescent wrench or socket. The box did not come with instructions but it did come with a parts list. I went online to download the instruction manual.

 


 I mounted the frame to the 6x6 timbers using five inch long, 3/8 inch Lag Bolts. There are four for each leg. The diagonal brace coming off the vertical leg is adjustable (three different positions) and allows the panel angle to be changed for the seasons.




  The long rails at the top and bottom are what the panels are attached to. Once I got to this point, I needed to turn the whole frame so that it was oriented south and then I had to level it with concrete pavers, which also gets it up off the soil so it lasts longer. I disassembled the 400 watt solar array and will think about where I can set that up to charge my Delta 1,300 unit.


  It was not easy putting the panels on by myself but I got it done. That is four 320 watt panels. Initially there will be two panels connected in series and then those two-panel groups will be connected in parallel to the solar generator. When I build a frame for the other two panels, there will be a set of three panels (connected in series) and each of those two sets will be connected in parallel to the Ecoflow. 

 One weakness of the Ecoflow system is the fairly low limits built into the charge controller. This system can take up to 1,600 watts of solar energy but you will never be able to accomplish that. This is because you are limited to only 15 amps and 150 volts of input power. My panels generate 48 volts each so you can only have three in series before you go over the 150 volt limit. To protect the system, the Ecoflow will not accept ANY current if the voltage exceeds the limit. Your panels can exceed the amperage, but the Ecoflow will only draw a maximum of 15 amps. So even though I will have over 1,800 watts of panels, it will be a rare day that I am charging with more than 1,400 watts of power. Therefore, it would take more than six hours of maximum sunlight to charge the unit if it was fully discharged. My goal is to never take it below 25% capacity.

 So, what was the cost? The Ecoflow solar generator and extra battery were on sale for $4,098 (they are much cheaper now due to a new model being released soon.). The six solar panels were $205 a piece (you can get used panels for half the price) for a total of $1,230. The aluminum panel frame was $279 and the wood was $56. The total was $5,384. I will get 30% of that back in green energy tax credits meaning that I paid $3,769. The next step is to wire this system into my house and I intend to run the kitchen, living room, bathroom, and one bedroom off this power system full-time, which will greatly reduce my monthly power bill. I have no idea what the payback period will be, probably a long time. But that wasn't the point. The point was to have a 100% independent source of electrical power at a reasonable price. 

 In the future, when power goes out, I will hardly even need to worry about it. The main rooms we use will already be powered and anything else I need to power, such as the well water pump, I can do with my gas generator.

28 Jan 24 update: Today it is raining with 100% overcast skies down to the ground. Not great conditions for solar power.

It is actually quite a bit darker than what this picture indicates.


 


 Even so, I am generating power with the three panels I currently have hooked up. It has been fluctuating between 82 and 120 watts, which isn't much but the 100 watt panel on my trailer roof manages to keep the single automotive battery fully charged. This trickle charge brought up the battery charge from 87% this morning to 97% when I took this screen shot. I will probably reach 100% before the day is over. These new, 320 watt panels really do a good job.

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