Solar power is a wonderful way to generate electricity, but sometimes you need more than you have installed. If you already have solar on your roof or don’t have additional space, a ground-mounted solar panel array might be a good choice. Today, we are taking a look at ground-based solar panels and sharing how we built ours.
What Is a Ground-Mounted Solar Panel Array?
Solar panels are often installed on a roof as a convenient location to capture the sun. But there are situations when this doesn’t work. Ground-mounted solar panels are sets of panels installed on a rack or pole mounted on the ground. You will commonly see this in solar power farms, but smaller setups can be used on private property.
Why You Might Want Ground-Mounted Solar Panels
When building an off-grid or mobile solar power system, there may be situations when expanding the solar array is ideal. For an RV or a camp, a ground-based solar array may be a cost-effective way to quietly generate additional electricity for all of your power needs.
Ground-mounted solar panels also have a few advantages over rooftop solar. First, they allow for a lot more space for larger setups if you have the property. Second, they can be positioned and angled to get the most sun and least shading. Lastly, having ground access to the solar panels makes it much easier to clean and maintain them if necessary.
While our RV has a substantial solar system built on it, we like to plug into a bit more power when at our camp. To do this, we built a cost-effective external temporary ground-based solar system to plug our RV into. This expands our solar generation capability by 1200 watts, providing all the extra power we need.
Need a refresher on RV solar systems? Check out our Beginner’s Complete Guide to RV Solar Battery Chargers
How to Build a Ground-Mounted Solar Array
There are two primary types of ground-mounted solar panel setups: temporary and permanent. You will want to determine which type you need to install prior to beginning.
A temporary setup will be used for a camp or RV spot not used full-time, while a permanent setup will be for a home or cabin used year-round. This article is focusing on temporary arrays for expanding solar systems. However, you can scroll down for some things to think about with permanent installations as well.
DIY Temporary Ground Solar Array
We built a 1200 watt temporary ground solar array that we plug into when we take our RV to our property. This article addresses many of the questions we receive about our setup. To build a ground-mounted solar panel array, the following needs to be considered:
What Panels Are You Using?
We built our ground array with cost-effective residential glass solar panels. These panels are 300 watts and cost us $150 apiece. Knowing your panel size is an important first step in building a ground-based array.
Determine Your Solar Panel Angle
When building your ground-mounted solar panel array, you need to determine the angle for best performance. If this is a temporary system that will only be used part of the year, you should optimize for that time of year. A few tools can help you do this.
First, Suncalc.org is an easy way to select the time of year and move the sun through the day at your location. This will give you the sun angle. Secondly, you can use PVWatts to figure your actual solar output based on month and panel tilt. Our sizing article walks through how to use this tool.
Building the Array
For a temporary array, you usually want it to be cost-effective, easy to build and disassemble, and portable. Stary by drawing out what you think your design might look like.
While your needs may be different than ours, we found that a simple set of triangles built from 2×4 timber was a great solution.
After a bit of geometry, we determined that we needed two 8 foot sections for the back 90-degree pieces. One 10-foot piece of wood supported the panels. We moved our primary angled piece around until we got the right angle using an angle finder. Then, we screwed the wood together with two wood screws per joint and replicated the triangles by laying the next set on top and building out all of them.
With two people, we stood up the triangles and installed a cross member to hold them together. This cross member also served to hold the bottom of the panel up while we secured them. Simple rafter ties mounted to the wood and bolts secured the panels to the triangles.
We built two sets of 2 panels with 3 triangles each. Once complete, we were able to drag the array into position. Then we secured them together with cross members and a few screws.
The forest shelters our location from high winds, so we did not anchor our ground-mounted solar panels down. However, you may want to anchor your array if you expect the wind to be an issue.
After we installed our panels, we built a junction box on the back of the array. Since our array was about 100 feet from the charge controller, we wired our panels in a set of series-parallel to get around 80 volts.
We used a simple electrical junction box and terminal block to make the wiring connections. We also used cable glands for all wiring penetrations. Then we made sure to leave an MC4 set of connections on the panels so that we could make the final connections with the connectors and would not have to work in a hot electrical box.
Solar Panel Junction Box
Here are the components we used to build our junction Box
We installed a disconnect and fuse at the charge controller end of our connection as well. Your array voltage and current will determine the size of your fuse.
WARNING: BE CAREFUL when working with live panels. Do not attempt to wire higher voltage panels like these if you are not confident in your electrical abilities. If you want to attempt it but are unsure of potential shock risks, cover the panels or make the connections at night. As a result, the panels will not be producing and will not pose a shock hazard.
How Well Does a Temporary Ground Array Work?
Overall, we have been very happy with our array’s performance. It expands our solar system to 4kw when we hook up. This enables us to run our AC and even slowly charge our electric car when we have excess power.
In the fall, when we are done using the array, we remove the ground-mounted solar panels and store them. However, we leave the junction box and framing intact for next year. Setup and takedown take about an hour, and the entire build took us about a day, including design and getting supplies.
What About Permanent Ground Solar Arrays?
First when designing a solar ground array for a permanent structure find out if you need to get a permit and inspection from your local authority. Be sure to know permitting and inspection requirements before embarking on this project, as you may need to have your design approved before beginning.
Permanent ground arrays come in two main types: pole mounts and rack mounts.
Pole mounts install panels on a single, tall pole affixed in the ground. This style gets the panels up higher and sometimes is adjustable to account for different sun angles through the year.
Rack mounts are typically lower to the ground. They consist of multiple ground mounts and the panels are mounted to a rack.
Both pole and rack mounts are installed in a permanent location, so deciding where they should go is critical. Choosing a location with the best sun exposure and least shading is ideal.
Permanent ground-mounted solar panels can be built out of wood or metal and will usually have a conduit running between the panels and junction box. Some permanent arrays have outdoor grid-tie inverters mounted underneath them or utilize micro inverters on each panel if they are grid-tied panels. If the permanent array is used for an off-grid application, array voltage and electrical run length are critical requirements in the design.
When designing a permanent ground-based system, selecting the correct angle is once again critical. If the array is not adjustable, you will need to determine if you want to optimize for summer or winter performance. Using SunCalc and PVWatts, as mentioned before, will help you make the right decision.
A Great Way to Increase Solar Capacity
If you have space, a ground-based solar array can be a great way to increase your solar capacity, temporarily or permanently. With easy access to the panels, no holes to drill in your roof, and relatively easy construction, a ground-mounted solar panel array might be the right choice for you.
Start Your Solar Journey!
Thinking about adding solar to your RV? Start here with our solar calculator to get an idea of what might be right for you!
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Sunday 14th of February 2021
I am considering portable panels temporarily placed on the ground around various campsites. What I would appreciate is suggestions on how and where to carry the panels on travel days.
Tuesday 23rd of February 2021
Marty, If you have the boxes the panels came in just put them in those. I put a leg on each upper corner of my panels to prop them up when outside. The legs will fold up when you put them in the boxes. Be careful of what's in front of the panels in case they blow over and get smashed. A thick blanket or pad can be placed on the ground in front of each panel as extra protection if they do fall over. You can also stake each leg into the ground to hold them in place.
Sunday 7th of February 2021
Hi Tom, Thanks for the very informative blog. Where can one get the 300W residential solar panels that you used?
Mortons on the Move
Sunday 7th of February 2021
You can order them online but because of the cost to ship one large unit they are usually cheaper to get locally. We got ours off craigslist from a guy who had extras from a construction project and had ordered an entire pallet (Always cheaper by pallet) Some solar shops and installers will sell them too. I have heard good things about these guys online tho. https://a1solarstore.com/
Wednesday 3rd of February 2021
Tom I once spoke with you when John and Peter introduced you a few years ago. I think you were playing with a Telsa battery plant. Sure love these toys. I am on my forth PV system (home & RVs) and I have been thinking about a supplemental ground system as we camp on our property in the trees near Lake Tahoe. Panels are dirt cheap these days, so why not.
In your system you mentioned running your 80 VDC (max) for about 100 feet into your MPPT 100 /50. Yet, I did not see any mentioned of wiring size consideration. From your picture it looks like you are using 12g wiring. If so that is about a 16% V-drop. I ask as I estimate I would need a 200' run and have been think about efficiency.
With 6G wiring, this is an 8% loss. So I started thinking about placing microinverters on the panels as this is what I did at home.
My AC based system at home is very efficient for running home loads directly. But that is not the case most of the time in an RV, as the batteries source most of the load when dry camping.
What are your thoughts?
Mortons on the Move
Thursday 4th of February 2021
Good question and something I should write an article about. That is 10 gauge wire to the RV we used. You right voltage drop is a bit more significant but the benefit of the MPPT and the higher voltage is that it doesn't really have an impact. In our case line losses are only resistive. The MPPT will run the voltage on the panels to whatever is most efficient so even tho the panel voltage and MPPT voltage are different it will still optimize. On the backside of the MPPT there will be no impact on battery charge performance. The voltage drop of course still becomes an issue if your voltage is not significantly higher than the batteries as the dip could cut charging early. This is even mitigated somewhat by the fact that early and late in the day current is so much lower and thus the voltage drop as well. This is why higher voltages are so much more beneficial for longer runs and using an MPPT is critical. If I were building your setup I would get a 250V MPPT and run the panels at 200-210 OC. From there you can calculate resistive line losses and not worry much about voltage drop for wire sizing. I have seen so many systems where the wires are so crazy oversized for the panels because this is not thought out.
Wednesday 3rd of February 2021
You might want to look at 3/4" EMT instead of lumber. I have had my system for over 10 years.
Mortons on the Move
Thursday 4th of February 2021
That's a great idea! would sure hold up better over time!