This is the third and final part of the “Sizing Your Solar Energy Panels” series. Have you done some calculations for your future solar power system yet? If you have been doing those mini exercises, you’ll most likely find a suitable solar panel for your home by now.

The next step requires us to find an appropriate-sized battery bank, inverter and charge controller. Let’s look at each of these:

1. The Inverter

The inverter you choose has to be sized according to the demands of the alternating current (AC) side of the circuit. Therefore you will choose a specification according to the loads in your house (with a little buffer in case you increase your loads over time). Pretty straightforward.

2. The Charge Controller

You’ll at least need a basic charge controller to begin with. Until you get fussy about how advanced you want this component to be, more affordable models will do just fine. You’ll need to get a specification that fits the output current (Amps) of your solar panel arrays. If you intend to scale up your solar power generator, you’ll do better with a larger charge controller with room to accommodate more solar panels than with two smaller-sized ones.

3. The Battery Bank

The size of your battery bank depends on how you want to use your solar panels. You can size your battery banks such that it can get you through thick clouds that pass by, or you can size them so you can get through three solid days of solar eclipse and a power outage at the same time. It really depends on you. But take note that over-sizing isn’t always realistic. You have to take into consideration the space they occupy and the how much they’ll cost you.

If your home is grid-tied, provided there aren’t frequent power outages, the size of your battery bank isn’t critical. Just size it to take care of cloudy days will do. You can still maintain your lifestyle by drawing power from the grid.

When you design your battery bank, you’ll have less power loss (through wires) if the voltage is higher. If you are able to design a 48-volt system, you can conserve more power than when you use a 24-volt or 12-volt system.

Continue Reading:

1. DIY Solar Panels — Charge Controller Basics
2. Sizing Your Solar Energy Panels – Part 1
3. Sizing Your Solar Energy Panels – Part 2

Electric golf carts use 24 volt, 36 volt or 48 volt systems. Most of them have 6 batteries. Thus if the batteries are rated at 6 volts, yours is a 36-volt system. Similarly, if the batteries are rated at 8 volts, you have a 48-volt system.

Every golf cart can make use of solar power to charge its batteries. There are solar panels in the market that can supply between 190 to 380 Watts per solar panel with an output of up to 88 volts. Therefore solar panel technology nowadays is more than sufficient to power golf carts.

When batteries are constantly recharged while out in the sun, their lifespan can be extended by up to 30%. This can also increase a golf cart’s driving distance by up to 12 miles every day. This helps you reduce the maintenance cost of your golf cart. On top of this, when you use solar energy, you reduce your electricity bills.

Solar panels are eco-friendly and have zero carbon emissions while operating. Moreover they are easy to install and are even easier to maintain. All branded solar panels come with at least 10 years of warranty so you will not need to worry about defects.

And if you are not willing to pay the solar panel cost upfront, some manufacturers even have a customized leasing program for you to take advantage of.

Most contractors will be happy to convert your golf cart for you at a small price, included in the package. You can also do this yourself if you want.

All you have to do is to first understand how your golf cart batteries are charged.

Some golf carts have their own in-built battery charger. You only need to supply it with 110 VAC to charge the batteries. Others require an external battery charger.

If your golf cart takes in 110 VAC, you can either use a DC-to-AC converter or get a charge controller and wire it directly to the batteries.

After understanding how your golf cart batteries are charged, you can proceed to mount the solar panels on the golf cart’s roof. Do note that solar panels are heavy and you may need to change (or reinforce) the supports to the roof.

Once the solar panel(s) are secured, take a little drive. If your roof sways from side to side, you may need more support.

Most likely, you will need to fit a charge controller to your golf cart. Find a compact model that can fit into an empty space inside your golf cart. This location must be shielded from water and rain so your batteries do not get short-circuited.

After securing the charge controller, the final step is to connect the charging cables to their respective terminals and secure them properly.

Within a few hours, you’ll be using solar power to charge your golf cart batteries.

Continue Reading:

1. DIY Solar Panels — Charge Controller Basics
2. How To Build A Solar Panel Charge Controller
3. Making A DIY Solar Powered Reading Lamp

Small 6-volt Solar Panel

One of the easiest solar DIY projects to build is a reading lamp.

It requires very little technical skills to build this and you can involve your children in the whole process.

Since it takes less than two hours to put this project together, you can also reap the rewards of your labor very quickly.

Here are some components you have to buy before you begin:

1. Small 6-volt solar panel
2. Battery clip for 4 AA-size rechargeable batteries
3. 4 AA-size rechargeable batteries
4. Charge controller circuit (for 6 volts)
5. Project box
6. Low-powered white LEDs
7. Connecting wires
8. Single pole single throw (SPST) switch

You may want to buy a project box to fit all these components into, or you can make your own. The choice is yours. You can even stick the solar panel to the window and pull the wires over to where your study is…

…that’s provided you’re ok with some mess.

First, you have to cut an opening for the solar panel. Then you can fix the PV panel at its position using screws, super glue or epoxy.

Next, you have to drill holes on the other side of the project box for LEDs to go through. The number of LEDs depend on how bright you want your reading lamp to be. I’ll use 12 LEDs arranged in a 4 rows by 3 columns fashion. You can have more if you want.

You need to leave some space to paste the charge controller circuit on the same side of the project box as the LEDs. (I’ll use a little silicon caulk to do this.)

After the LEDs are glued into position, you can bend their legs (leads) and solder them according to the circuitry you designed.

It’ll be good to put a thin piece of sponge or rubber over the LED array to prevent short circuit.

Finally, solder the connecting wires between the battery clip connectors and the charge controller, between the charge controller and the solar panel, and between the LEDs and the battery. (Remember to solder the SPST switch between the LEDs and batteries.)

Note: Here are typical characteristics of a reading lamp you may want to incorporate into your design…

- It operates for at most 2 to 3 hours everyday at night.

- They are only required to illuminate up to (max) 3 feet in distance and covers an area of about 5 square feet.

- They must be light so they can be easily moved to the window for charging.

Continue Reading:

1. 10 DIY Solar Projects You Can Build In Your Backyard This Weekend
2. Lighting Up Your Yard or Garden Using Solar Energy
3. How to Make a Solar Powered Tricycle

It is important to have a charge controller. Otherwise the batteries will either not get charged or they could be damaged from overcharging. In order to charge a 12-volt battery, the regulator (charge controller) will have to maintain a charging voltage between 14.0 to 14.5 volts.

There are many types of charge controllers you can build. The easiest is the simple on-off type shunt regulator. This type of charge controller is simple, efficient, easily built, and cheap. It is also pretty reliable. Its small size makes it portable. Thus you can use it on many applications like your yacht, car and recreational vehicle (RV).

However the voltage on the battery will not be very constant. Disconnecting the battery can also result in high voltage output spikes from the regulator unless precautions are taken.

There are other design considerations that you may want to implement:

1. When the solar panels are not generating electricity, the circuit should be turned off. Otherwise current can be drained through the PV panels. When the sun is up and the PV panels start generating a fair amount of electricity, you can use transistors to start directing the current into the batteries.

2. As long as the rechargeable batteries are below 14 volts, the batteries get charged. When the batteries reach 14.0 volts, it is fully charged. Thus the circuit needs to stop current flowing into the batteries. You can use an operational amplifier (op-amp) to achieve this effect.

The components needed for building solar charge controllers are common and are therefore easily available. The operational amplifier you choose should be of a low power rating so there is lesser current drain through the component.

Here are some components that you can use as main components to your circuit:

TLC271 Operational Amplifier

a. TLC271. This operational amplifier combines a wide range of input offset voltage grades with low offset voltage drift and high input impedance. It also offers a bias-select mode that allows you to select the best combination of power dissipation and ac performance for your application.

b. SB540. This is a Schottky barrier rectifier. The advantage of using such components instead of standard silicon and germanium diodes is that the forward voltage drop is only in the range 0.15 to 0.46 volts as compared to a 0.3 or 0.6 volts respectively.

For the components that you use around these components, their % tolerance is not critical.

These components can be fixed on a printed circuit board or perf-board as usual. Then you can mount it in a protective box of your choice, depending on the environment you are going to use this in.

A solar panel charge controller like this can be built in an hour after you’ve got your PCB etched and ready. And it’ll probably be cheaper than you imagine.

Continue Reading:

1. Have Your FREE Bonus eBook “How To Build A Solar Panel” Emailed To You Now:
2. DIY Solar Panels — Charge Controller Basics
3. Making A DIY Solar Powered Reading Lamp

If you’ve ever built DIY solar panels of a considerable size, you’ll probably come across this important component — the charge controller. The role of a charge controller is to regulate the charging voltage on the batteries.

When sunlight gets brighter, solar cells produce more voltage. Excessive voltage may cause over-charging which may damage your batteries. You’ll need this component if you want to store excess electricity from your solar energy panels.

Many modern charge controller units have a 3-stage cycle:

1. Bulk Phase – During this phase, the charging voltage gradually rises to approximately 14.4 to 14.6 volts (to charge a 12V battery). It is at this stage when charging current is maximum.

2. Absorption Phase – Voltage is maintained at the bulk level for a specified time. As the battery is charged up, current tapers off gradually.

3. Float Phase – After the absorption phase, voltage is lowered to about 13.4 to 13.7 volts (float voltage) and batteries draw a very small, maintenance current until it goes through the discharge cycle.

There are several different types of charge controller to choose from — some with fanciful LCD displays and others with battery temperature monitor. If you are building your first solar power generator, it may be more practical to buy basic ones to begin with. After you’re more acquainted with these components, you’ll have more knowledge to get the most out of more advanced charge controllers. Most multi-stage, Pulse Width Modulation (PWM) types of charge controllers will do great, really.

Continue Reading:

1. Solar Energy Panels For Big “Toys”
2. Sizing Your Solar Energy Panels – Part 3
3. How To Build A Solar Panel Charge Controller