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:

> 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

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.

Here are some additional important articles:

• How to Turn Wind Into Electricity
• Heating Your Home with a Simple Solar Water Heater

Download pdf here  

This is a comprehensive but easy to understand technical guide to batteries which are specifically appropriate for solar power systems. The article covers the following topics:

• Battery types useful for solar power systems
• Understanding how batteries are rated
• How to size batteries to a solar system
• All about charging batteries
• What you have to know about battery storage
• How to do battery testing
• Procedures, rules and remedies for various situations and problems concerning batteries

To get the most out of this guide, it would be best to take this short, free and somewhat entertaining course first.

Solar electric power, like every other source of energy, has its advantages and disadvantages. The table below lists the major benefits and shortcomings, and how to get around the shortcomings.

In summary, keep this in mind:

• Do not depend on any single source of energy for your vital household functions. ALWAYS have a backup system for at least emergency use.
• Solar electric power is costly to install but pays for itself over time. The high initial cost can be greatly reduced if you build your own solar panels.

Inverters are used to change direct current (DC) from batteries to alternating current (AC) which is required by many household and shop devices.

Download pdf here  

This is a comprehensive but easy to understand technical guide to inverters appropriate for solar power systems. The article covers the following topics:

• Understanding the basics of inverters
• How inverters are different in terms of the quality of power output
• Which type of inverters are most appropriate for small, off-grid applications
• Guidelines for selecting an inverter
• How inverters vary in their capabilities
• How to size an inverter for your system

To get the most out of this guide, it would be best take this short, free (and somewhat entertaining) starter course first

An Explanation of Deep Electronic Wizardry For
Non-Wizards

In the world of off-the-grid home solar power systems, charge controllers make it possible for your solar panels to charge your batteries in the most efficient way possible. There are simple ways to do this – which are cheap but not very efficient – and there are sophisticated ways to do it – which are expensive and highly efficient. Let’s go over the different types, from simplest to most sophisticated.

Single Stage Charge Controller

This is a device which just dumps power in bulk into your batteries at a uniform rate until the charge controller’s internal detection device determines the battery has achieved a specified voltage.

This kind of charge controller could be an electrical device but it could also be YOU. You can hook up your solar cell directly to the battery, let it charge and test it periodically with your multi-meter every so often to that it doesn’t over- or undercharge. It’s cheap, it’s simple but it’s not good for the battery.

Lead-acid batteries, the kind most used in solar power systems, don’t like to be fed at the same rate all the time. Here’s why:

• As they get more full, they prefer to be fed more slowly.
• If they aren’t fed more slowly, they don’t ever get fully charged.
• If they don’t get fully charged, they begin to get more and more sulfate deposits on plates.
• As they collect more sulfate on the plates, they accept less and less charge.
• And so on until you have a very dead battery
• The other problem – which is even worse – is that if the voltage is too high, it will cook the battery!

So the wizards of electronics came up with the …

Two-Stage Charge Controller

This device divides the task of charging your battery into two sections:

Stage 1 – Bulk Charging: This is the same as the first stage above. It quickly fills the battery at a high voltage and high amperage except that it is also smart enough to know then it has filled the battery to only 90% capacity.

Just to review, using the analogy of a water hose, the voltage is like the water pressure; the amperage is like the amount of water passing through the hose in each second.

Stage 2 – Float Charging: What happens after the 90% full mark is reached, the charger lowers the feeding voltage to just above the maximum voltage of the battery (usually around 13.5 volts). It will also lower the amperage.

In this way battery cannot be over charged. And as mentioned before, the battery will get more fully charged if it is fed more slowly as it nears its maximum recharge state.

Three-Stage Charge Controller

This design is even more sophisticated. It can charge the battery faster than a two-stage yet still prevent it from overcharging. It can also keep the battery topped off. Here’s how it does it:

Stage 1 – Bulk Charging: This is the same as in the two-stage charger; it fills the battery quickly to 90% full.

Stage 2 – Absorption Charging: In this stage the charger maintains the same voltage as in Stage 1 but tapers off the amperage.

To taper off the amperage, the three-stage charge controller has a special circuit that detects how full the battery is and automatically adjusts the amperage to fill it quickly yet not overfill it.

Stage 3 – Float Charging: This is a way to keep the battery topped off even if it  has a constant load on it. In other words, if you have a battery that has been fully charged but is connected to a device that is constantly using some of its power, the float charging part of the charge controller will continue trickling power into the battery in order to compensate for the drain from the device as well as any “natural” discharge the battery experiences over time. (All batteries eventually discharge even if not connected to anything.)

Electrically, float charging involves sending the required amount of electrical charge (amperage) to the battery at a pressure (voltage) just slightly above the battery’s maximum voltage. This will keep the battery fully charged at all times without causing any damage.

Pulsing Width Modulation (PWM) Charge Controllers

While researching how to get the most charge possible into batteries, the electronic wizards discovered two very interesting phenomena:

1. In the final stages of charging, if they sent the electricity to the battery in tiny, short bursts instead of continuous chunks, the battery could take on more charge.
2. Pulsing also helps breakdown the sulfate crystals forming on the plates.

So a “PWM Charge Controller” is really a three-stage controller with this extra little twist. During the FLOAT stage of charging, the power is sent in extremely rapid pulses. There are special electronic circuits inside the device to check continuously how charged the battery is and adjust the length and strength of the pulses accordingly.

You can think of it as topping off your gas tank. As you near the top, you probably have discovered that you can squeeze more into tank if you slow down the flow. But also, if you are very careful to squeeze a little in and then stop and let it settle, over and over, you can fill it right to the top without it overflowing. This is a bit like what PWM does for your battery.

Incidentally, it might be important to know that the electrical pulsing of a PWM charge controller might interfere with very sensitive electronic equipment if you put them close together. When planning your setup, you might want to keep this in mind.

Maximum Power Point Tracking Charge Controller

The next level up in charge controller sophistication is called Maximum Power Point Tracking or MPPT. This feature has to do with not charging the battery but getting the most power out of the solar panel itself.

Most explanations of exactly how this works depends upon understanding something about electronic formulas and so forth. For the purpose of keeping this as non-technical as possible, envision it this way:

To produce the most electricity possible, the solar panel has to have two rules satisfied:

1. It has to have as much sun as possible. The more sun, the more electricity it can produce (up to its maximum). This is obvious.
2. It has to have a load attached to it. This is not so obvious. What does this mean?

Rule #2

“Load” is anything the electricity can make happen, something to resist it, something to push or some work to do. Like run a motor, a heater, or … charge a battery.

From the point of view of the electricity being generated by the panel, it wants to feel it has something to do. If the wires from the panel are not attached to anything, it has no where at all to go & nothing to do. The electrical geeks would say that there is an infinite resistance in the line, so of course nothing can flow.

Think of child wanting something to do. If she has no way to get out of the house; she just sits home and pouts.

On the other hand, if there is no resistance at all in the line, if the positive and negative wires are touching each other (shorted out), all the electricity made by the panel is just running around doing nothing.

This would be like our child running out the front door and returning through the back door without really having done anything. Sure, she is busy but not much of anything is really gets done.

Now, if you put some different levels of resistance between the negative and positive wires of the solar panel, all of a sudden something very interesting happens. There is going to be some amount of resistance that perfectly provokes the panel to generate the maximum amount of power it is capable of.

In our analogy, this would like the child having just the right amount of things to do without getting overwhelmed or too bored.

Of course we still have to remember that the maximum electricity production of the panel also depends upon how much light is hitting it, which leads us back to  …

Rule #1

This rule says the more sunshine, the better. So if the weather is nice, the child wants to keep as busy doing things outside. The cloudier it gets, the less energy she has, the more she wants to say in the house and not do too much.

So, as it gets cloudier and cloudier (or as night time comes), we have to adjust how much there is for her to do. If we don’t reduce the amount of things she feels she has to do outside – but doesn’t have the energy for – she’ll get frustrated.

In the case of solar panels, as it gets darker outside (maybe because a cloud just passed overhead), we have to reduce the amount of load or resistance between the positive and negative wires of the panel. As the cloud moves away, we again have to put more load on the line.

If we keep adjusting up and down the amount of resistance in the circuit as the clouds pass, we can get extract the maximum amount of power that the panel is capable of at whatever level of sunlight we happen to have at the moment.

That’s is why its called “tracking the maximum point of power” for a solar panel, or “Maximum Power Point Tracking” or MPPT. Having this kind of capability in a charge controller means that if the panel gets shaded because of clouds, leaves, dust, Uncle Jake sitting on it or whatever, the system will adjust for the change in light and keeping producing the maximum amount of power it possibly can.

Pretty neat, eh?

There is a lot of good information available on how to size solar power systems but very little of it applies directly to folks who are “going 12 volt”, looking for emergency home power, or “homesteading your home”. One of the stumbling blocks in building a inexpensive photovoltaic power system for your home is figuring out how much power you really need. People often get stuck right there and never get started.

When you do your homework and start to find out just how much energy you are really using and just how big a solar power system you would need, the numbers quickly become overwhelming. Electrical power from the grid is very cheap and most of us use far, far more of it than we ever imagined.

But the task of sizing become much easier if you:

• Focus on your existing critical power needs
• Gradually reduce your power needs by shifting to lower wattage equipment

Critical Power Needs

Your short-term critical power needs are often much less than you think. For someone already working toward local self-reliance, a power blackout lasting several hours to several days might mean keeping some minimal equipment operating.

(Note: 1 watt-hour is 1 watt being drawn over a period of 1 hour.)

Another article (Building Your Own Solar Panels versus Buying Them) discussed a low-cost 520 watt solar power system. If it were running at only 75% efficiency (due to clouds, shadows, etc.), it would very likely be capable of providing you with the power budget above.

(520 watts x 5 hours/day x 76% = 1,976 watt-hrs)

Of course “your mileage may vary” but this gives you some idea about how to size a simple system; one that you could quite easily build yourself.

Getting your entire home off the electrical grid can be very expensive. However, building a small system that uses solar power to give you to give you an alternative source of energy for some crucial equipment (laptop, cell phone, lights, 12 volt heating blanket, etc) in the event of a power blackout is not very costly at all. Making a solar power backup system is very practical and an easy first step in the direction of personal energy independence and security.

For most people, the cost of converting their entire home to run on solar power is likely to be overwhelming. While there may be families which could spend $20,000 to $25,000 for a complete, professional system, there are few “average” families that can even dream of doing this. One answer is to create your own alternative solar power system little-by-little.

To be practical, your first emergency power system should be:

• Easy to build
• Inexpensive
• Made from commonly available components
• Easy to operate and maintain

There is a great deal to know about solar power and solar power systems and for that reason, getting started is much easier if you keep it extremely simple and learn as you go without spending a lot of money on it to start with.

For this reason, we won’t worry about what is the “best” way to do it; instead, we’ll focus on something that works well enough and that can be improved upon later, if you wish.

This simple system will be good enough to operate your computer, monitor, some lights and perhaps a small battery charger in the event of a power blackout.

Creating Your First Solar Backup Power System

The materials you will need are:1. Heavy-duty 12 volt automotive battery, preferably, one used for a truck or other heavy equipment. (We’ll go over all about which batteries are best in another article.)
2. Inverter. This is a device that changes direct current (DC) – such as batteries store – to alternative current (AC) 120 volts that normal household appliances use. The really good ones can get expensive but for powering a laptop computer, recharging your phone, running a small TV or DVD player, running some lights, etc., an inexpensive one from Walmart or Radio Shack will do fine. A 375 watt inverter might cost you around $50; a 220 watt model might cost you as little as $17.	A typical low-cost inverter – this one is rated at 375 watts and costs $47 at Walmart.
3. Cables and any adapters to connect the inverter to the battery. Usually they come with cables and alligator clamps or a cigarette lighter adapter. You’ll have to check the model you buy to see what it needs.
4. DIY solar panel building demonstration video. There are several decent versions out there. A video is far better than any written instructions or even pictures, and makes the whole process very easy to understand.

Any of these popular educational kits will do:
GreenDIYEnergy	Earth4Energy
For reviews of these products, go to DIY Solar Video Training Kit Reviews.

5. Multi-meter. This is an electrical device for measuring volts and amps that will be used for a variety of purposes as you go along.

A $7 multi-meter

6. DIY solar panel components kit. If you are building your first panel, get a small kit that will enable you to build one 65 watt panel. This is all you will need to start with. After you build your first one, you will understand the whole process. For your first panel, I would recommend getting the 40-cell kit from MLSolar. Go to E-bay and for these search terms: “40 3×6 Solar Cell Kit with tabbing, bus, flux, diode”. Everything else you will need you should be able to get at a local hardware store.

A typical 36 to 40 solar cell kit available on E-bay A typical 36 to 40 solar cell kit available on E-bay

Using Your Basic Solar Emergency Power System

1. Attach your solar panels directly to your battery to recharge it as needed. HOWEVER! since this is a very basic system, there is no charge controller – which is a device that prevents your battery from getting overcharged. Instead, you are going to have to check your battery’s charge with your volt meter every few hours while it is charging. This is not hard to do but don’t forget! There is much more to know about this but the basic rule is do not let your battery charge to more than 12.6 to 13 volts.
2. The inverter should be attached directly to the battery, either during or after charging.
3. Plug your vital low-wattage AC appliances into the inverter or use any adapters necessary to power your DC equipment.
4. Your emergency power system is now ready to use.