Building vs Buying Solar Systems

Building Your Own Solar Panels versus Buying Them

Just as you should know how to grow your own food – but may not ever grow all of it – you should also know how to make your own photovoltaic panels. It’s not hard, at least not any harder than making beef stroganoff. Building solar panels for your home can cut your per-watt cost in half, but it is not always the best choice for every situation.

There is a time to buy and a time to build. Failure to understand the trade-offs involved can be expensive either way.

Commercially-made panels are made to highly exacting standards in a very competitive marketplace. It is this market-driven competition that forces them to be made with increasing quality. For example, almost uniformly they are:

  • Well-sealed against moisture – which could corrode the electrical connections and limit the amount of light able to pass through the glazing
  • Machine soldered – which generally produces a high level of standardized quality to the electrical connections
  • Appropriately framed, providing the rigidity required where fragile but efficient “mono-crystalline” solar cells are used.

As a consequence, these panels can usually be counted on to serve for 20-25 years.

Homemade panels cannot benefit from such highly standardized commercial methods. If you don’t make them carefully, moisture will enter and, in some environments, cause them to rapidly degrade. On the other hand,

  • if they get damaged they can be rebuilt … by you … because you know how and because you remembered to stash away some spare parts
  • You can also buy a stock of the parts inexpensively and build the panels a few at a time as you can
  • They will cost far less per watt.

Assumptions

Let’s look at this in more detail using an example with a typical 65 watt panel Let’s also assume:

  • You want to make a system capable of producing about 520 watts-hours of power. (1 watt-hours is 1 watt being drawn over a period of 1 hour.)
  • On any given day you might have only 5 hours of useful sun because of clouds, shade or whatever else many interfere. (If you are living in a very foggy or cloudy area, obviously the number of hours could be much less.)
  • 520 watts-hours x 5 hours = 2,600 watt-hours per day, more or less. This is probably quite a bit less than you typically use in your home per day; however, it is still quite a bit of power if
    • You want emergency backup to keep basic, crucial equipment operating (refrigerator/freezer, computer, some lights, etc.) operating during a power black-out
    • You are optimizing your living situation to a “12 volt lifestyle” (similar energy-wise to how someone might live in an RV or on a boat)  It should be enough power to operate in 12 volt lifestyle  “maintenance mode”, that is, not running much in the way of 120 volt shop equipment.

This means you will need eight (8) 65 watt panels.

Costs: Commercially Manufactured Solar Panels

As of August 2010, a broad survey solar panels commonly available in the U.S. shows them to be costing from $2.44 up to $15.60 per watt.

Let’s assume:

  • You’ve done your homework and found a deal on panels at $2.44 per watt.
    (Divide the cost of 1 panel by the number of watts it is rated for.)
  • You will need 8 panels of 65 watts each.
    (8 x 65 watts = 520 watts)
  • At this rate, each panel of 65 watts will cost $158.60
    ($2.44/watt x 65 watts = $158.60 per panel)
  • Eight panels will cost $1,268.80
    ($158.60 x 8 = $1,268.80)
  • Unless your best deal happens to be very local, you’ll pay an estimated $30 per panel for shipping. Of course this amount will vary depending upon where it is shipped from, where you are, etc. But $30 per panel is a fairly reasonable estimate from my research. So total shipping will come to about $180 for the lot of them.
    ($30 x 8 panels = $240)
  • Total cost for 8 panels including shipping = $1,508.80
    ($1,268.80 product cost + $240 shipping = $1,508.80)
  • So with shipping, your REAL cost per watt is $2.90
    ($1,508.80/520 watts = $2.90/watt)

Costs: DIY / Home-built Solar Panels

There are a number of different ways to build solar panels. Some methods produce more robust results than others, and this topic is covered in another article.

Let’s assume:

  • You use one of the least expensive methods out there (utilizing wood framing and a clear, untreated acrylic face.)
  • You do the construction labor yourself
  • Materials for panel construction should cost about $92.16 – so let’s call it $100. This includes shipping for the items you probably won’t be able to get locally at the right price. Details on this calculation will appear in a separate article.
    (Materials cost = $100)
  • At $100 per panel, the per-watt cost is
    ($100/ 65 watts = $1.54)
  • An array of 8 panels will cost about $800, maybe less if you do your homework
    ($100 x 8 panels = $800)

Now we can put the figures in a table and run a cost comparison:

Costs Commercially Manufactured Solar Panels Homemade Solar Panels
Real cost per watt $2.90 $1.54
Real cost per 65 watt panel approx $189 approx $100
Real cost for a 520 watt array approx $1,509 approx $800

> Important! We are only examining here the per-watt cost of panels, not of an entire solar power system. Keep in mind there is more to the system than just the panels. <

Service Life: Commercial vs Homemade Panels

If well-protected, the high-efficiency mono-crystalline solar cells have a service life of 25 to 30 years. However, the big question is: How well are the cells protected during use?

What can go wrong?

Panels can be damaged by weather, animals and people.

  • The clear protective front covering can be punctured which may:
    • Speed up the weathering of the electrical connections
    • Crack the very fragile solar cells
  • Caulking can leak – which is not usually a problem with commercial models since they are usually very well sealed. How well your DIY panels pass this test depends upon how well you make them.
  • Some panels (commercial or homemade) can easily be damaged if dropped or twisted during handling. Again, the cells can be shattered and the weather seals broken, admitting corrosive elements.

What can be done if a panel gets damaged?

  • For commercial panels, repair is possible but can be very problematic because they are basically not designed to be repaired. They are permanently sealed and getting into the enclosed elements is almost always quite difficult. And re-sealing it after repair is done can be even more difficult.
  • Repairing a commercial panel requires the same (or even more!) skill required to build one yourself.
  • Homemade panels can be built in various ways that anticipate the possibility of damage, thus making repair much easier.

In Summary

Commercial panels DIY Panels
Construction None required Can require a bit of time to build depending upon the size of the system; involves a learning curve
Cost Varies, but typically 2x or greater than homemade About 1/2 the cost of the cheapest commercial panels
Quality Uniformly excellent Highly variable; depends upon the design and the workmanship of the builder
Service Life 25-30 years if undamaged Depends upon the design. Some could last as little as a few months.
Damage resistance to impacts Varies greatly Depends upon the design. Can be adapted to local hazards.
Damage resistance to natural elements (sun, moisture) Depends upon the design but generally constructed in a robust manner, driven by market demands. Depends upon the design. Can be adapted to local conditions.
Maintainability Uniformly very difficult Depends upon design. Can be made quite easy to maintain.

Building your own solar panels isn’t for everybody, but then neither is “Going Solar” or getting off the grid. Those who are ready to build solar panels will find the process is far easier with the help of a good video training system; see our reviews of diy solar video training kits here.