Solar Panels for Homes
and Why They Differ From Solar Panels for Camping
My purpose with this article is to discuss how I look at solar panels for home versus solar panels I would consider using on the road or off-grid camping. You may be thinking that solar panels, or PV Modules, are all basically the same. Sure, there are output differences, but really, if you've seen one, right?
Let me state for the record that there are differences, they are somewhat subtle, but they are important to be aware of and knowing what to look for when choosing PV Modules really depends on what your intended uses and goals are for your system. How much electrical power do you wish to produce? This question is a proverbial ‘can of worms', as you will see.
A big issue with residential solar power production is in the area of power loss. With multiple panels in an array located some distance away from the electrical service panel, and with wire resistance inherent in all circuits, power loss adds up and can become significant.
This problem is offset by using heavy gauge wire connecting the solar array to the inverter or charge regulator, and various solar module series and parallel wiring techniques, that manipulate the DC voltage coming from the panel (more than one PV module) or array (more than one panel).
This is because solar modules tend toward higher current production than they do pressure or voltage, but higher voltage travels better through electrical wiring, which means less loss to resistance than does lower pressure (voltage). Sounds confusing, but its really pretty simple. Doubling the voltage coming from the source, which is the solar panel, by wiring its modules in series instead of parallel, significantly reduces power loss as measured at the string inverter, or the controller.
When considering solar panels for home use, your main priority is to determine what is your average daily electrical power consumption, and whether you want to build enough solar power infrastructure on your property to replace all the power you are currently purchasing from the utility. You may ultimately find that due to space or economic limitations, reducing rather than eliminating your reliance on the national power grid makes more sense.
I think it is exciting that we get to make this choice!
But, generating 5 – 7 kilowatts of power ( 5,000 to 7,000 watts) from a roof mounted system, requires about 5 – 7, 250 watt solar panels, and 4 sun hours at a minimum.
Looking at my most recent power bill, my daily average power use was 69 KWH per day! So I would need 60 or so 250 watt PV modules to cover my power needs. Wow! Granted, this is typically my peak power usage month of the year, but then again, it is also the best month to use in planning a system.
This is where you begin to wrestle with concepts such as grid-tieing, battery banks, roof mounting, tracking and so forth.
The average residential solar panel is 65 by 39 inches, or 211.25 square feet. 60 panels would thus cover 12,675 square feet?! My first residential lot I owned was a quarter acre, which is only 10,890 square feet.
So I might want 360 watt or 400 watt panels, except that I would still need about 40, 400watt panels and, due to their larger size, approximately 267 square feet each, we are still talking 10,666 square feet of solar array.
The main point I keep bumping into with solar panels for home use are their large size and the logistical issues of stringing enough of them together to handle most power contingencies that occur in the residence throughout the month. This is part of why a whole house, off grid solar electrical system is a huge deal. It is, in fact, huge!
This is also why I am a big fan of the grid-tied concept where the goal is the reduction of the reliance on the national grid, not the elimination of it. The grid-tied system functions perfectly with a single solar panel, and as time and money permit, can be upgraded with additional PV modules for greater impact. But regardless of that, the grid-tied system can be built in proportion to available space and the need to overbuild total capacity as a contingency for cloudy days or seasons, is eliminated.
Solar Panels For Camping
Here, the logistics are obviously completely different from solar panels installed at my residence. My power requirements are dramatically reduced while on the road or at a remote camp site. I am acutely aware of my energy use, as I carefully monitor my battery bank condition and limit simultaneous use of electrical appliances etc.
Physically, I lack the room to store a huge solar array while traveling, and roof mounting is also limited by the relatively small open space on top of my camper. Aside from the fact that I am not a fan of roof mounting PV modules as I explain in another post which you can read here.
Power loss is another important difference between a portable solar panel setup and a residential system. When camping, I am much less concerned with power loss from wire resistance, simply because my panels are movable and are physically close to my solar charge controller. My wire is 20 feet long versus hundreds of feet my residential solar array requires.
Voltage is not a thing, Voltage is EVERYthing
The camper and tow vehicle contain 12 volt DC electrical systems, while my residence is 110/220 volt AC. PV modules produce direct current, and unless this is converted at the source by a MPPT inverter, the electricity flows into the charge controller or inverter also as DC or direct current. In a vehicle or camper already operating on 12 volts DC, this is a big advantage because no power is lost to the conversion of DC to AC.
Also, smart phones, tablets and many electrical appliances such as lighting that you might take along camping run on DC, so an off-grid camping system can be kept very simple and small, and still provide very useful and plentiful power for these electronics.
Unlike a home solar panel system with scores of PV modules, inverters and wiring schemes, and high voltage with long wire runs being the norm, solar panels for camping may consist of a single or double panel, single or double battery, charge controller and little else. Either system will likely employ an inverter to produce AC for larger appliances, compressors and AC motors, but the enterprising minimalist will likely find the 12 volt DC world quite full of adaptable motors and electrical appliances.
Check out Do It Yourself 12 Volt Solar Power at your library or from Amazon to see some amazing creativity employed by Daniek to live in a 12 volt DC world.
So, Are The Panels Themselves Different?
While you won't find PV modules labeled Home or Mobile, when you look at the products being sold today you will see definite distinctions between panel size, voltage, and materials that are just as important to the intended use of the module as is the electrical output rating.
My article What is the Best Type of Solar Panel, and Does That Even Matter? discusses many of the currently offered panel types and it becomes obvious that modules such as building-integrated photovoltaics are not intended for a camping application. Of course, this could change over time which is one of the many exciting things about the solar power industry.
So, yes! Solar panels for homes are larger, tend to be series-wired to produce higher pressure electrical output, and are increasingly being integrated into, rather than onto the supporting structure itself. (Building-integrated photovoltaics, window-integrated photovoltaics, etc). On balance, the more exotic, cutting edge solar technology lends itself to installation at a fixed site where the logistics of portability are not a concern.
Solar panels for camping share basic design concepts, but are usually smaller, more rugged and often more integrated as with the various suitcase systems and portable generators being sold today.
Whether you are considering a residential solar system or a small portable setup, the best advice is to start with a good idea of your power consumption requirements, determine the battery configuration sufficient to supply that, then build your solar power system that is adequate for the care and feeding of your batteries, without punishing them to an early death with heavy and frequent power cycling.
That's a tall order for sure! ….you're gonna want to stick around.