Welcome to ecobuildsupply.com

Agape’ Productions, LLC-dba: Ecobuildsupply.com-E-Mail: info@ecobuildsupply.com or Call: 608.604.2341

A Non-Technical Introduction to Solar

There are four major components to solar electric systems; Solar Panels, Charge Controllers, Batteries and Inverters. All of these components are necessary to have a functioning Solar Electric (PV) system. The solar panel is the basic building block of the system. This is your battery charger. If you have several solar modules wired together you have created a solar array. The size of the solar array determines the amount of power or energy that will be produced. Your location is also a factor in the amount of energy produced. If you live in Florida, Southern California, or Texas you will produce more than if you live in Oregon, Maine or Maryland. In general the closer to the equator you live your system will produce a larger amount of energy. Do you want to know how much power can be produced in you area. Check out our FAQ question "How much power will a solar module produce at my location?" Charge controllers come in many different sizes and types. They all basically do the same thing. The charge controller prevents the solar panel or array from overcharging your battery. Batteries are the energy storage for your system. Without batteries there is no way to store the energy your solar panels produce during the day. Typically loads receive their power from batteries instead of directly from the output of a solar panel. A solar panel produces a high voltage that will damage electronics if loads are powered directly. A common application for solar panels directly powering a load is water pumping. Instead of storing energy you store water. This way you can pump during the day and have water all night. Batteries will provide you with the energy you need at night. The last major component is the Inverter. The inverter converts the DC energy stored in your batteries and turns it into the AC power you use in your home. Inverters are rated by wattage and the quality of their output. You can use a 50 watt inverter that plugs into your car 12 volt outlet to power a computer, or you could have a 4000 to 11,000 watt inverter system that powers your home. These major components can be put together in many different ways. Minor components like wire, disconnects, circuit breakers, and fuses are also needed for a complete system.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Types of Solar Energy Systems

Types of Solar Energy Systems width="23%">

Energy Source	Connected to the electricity grid?	Energy storage device in the system?	Examples
*Grid-tied solar system**	Solar Cells**	Yes	No	Home system that draws on the electricity grid at night and exports excess power in the day
*Stand alone grid- tied solar system**	Solar Cells**	Yes	Yes (batteries)	Home or business system uninterruptible power (e.g. for computers, servers). Still operates when the grid is down
Stand alone solar system without energy storage	Solar Cells**	No	No	Water pumping
Stand alone solar system with energy storage	Solar Cells**	No	Yes (batteries)	Remote homes, lighting, TV, radio, telemetry
Stand alone off-grid Hybrid solar system	Solar Cells** in combination with another energy source (e.g. diesel, wind)	Most often not	No	Remote large scale communications, industrial uses

* also known as grid connected
** also known as photovoltaic cells

Stand Alone or "Cabin" Systems

Solar---Charge Controller---Battery---Inverter---AC Loads

Solar---Charge Controller---Battery---DC Loads

A Stand Alone solar system is just as it sounds. It is not connected to the utility or other types of charging sources. This type of system is used when utility power is not present and is to costly to bring in from the nearest pole. If you have a shed set off from the house, a cabin in the mountains, or a summer home by the lake that is without power this type of system can often be very cost effective. When compared to bring in the power lines the initial cost can be less. Some of the pros of this type of system are: The lack off reliance on the utility. Potential cost savings. Some of the cons of this type of system are: Even thought there maybe a cost savings over running utility line, there can be a high initial cost. You have to know your loads and have the system designed correctly since you don’t have utility power for backup.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Utility Tied System

Solar---Inverter---Utility

This system is the newest addition to our site. The system utilizes an inverter that does not require batteries. During the day, the power generated is fed back into the utility. If you are producing more power then you are using your meter can even spin backwards. Due to the simplicity of the system, it has the lowest cost per watt. The downfall of this system is that when the utility grid fails the system will shut down.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Battery Backup System

Utility---Battery Charger---Batteries—Inverter---AC Loads

This is a system that does not involve solar power. This system utilizing an inverter that has a built in battery charger. It will charges batteries and hold them at 100% waiting for a power outage or a brownout. Your critical loads will never see the power outage. Computers, home health equipment, and lights will continue to operate when the utility grid fails. This is a system that is great for areas where power is lost for short periods of time. The limit on this system is the amount of battery capacity that you have. The larger the batteries the longer your run time will be.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Utility Tied Battery Backup System with Solar

This system operates on the same principal as the Battery Backup System. The difference is the addition of solar. The solar is used to charge your battery bank. When the batteries are full the excess power is fed back into the grid. In the event of an outage, your critical loads are powered by the system, and the solar panels continue to charge the batteries. The benefit of this system is that you have the ability to sell power back and have the piece of mind that you critical loads will continue to operate. The drawback is the cost per watt is higher then a Utility Tied System.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

We have seen an explosion in questions that refer to grid tied systems. Specifically how do you select a system that is right for you.

Let me first correct one misunderstanding that happens often. I have a 1800 square foot home. The size of the home has nothing to do with how much solar you need. It's all about power.

Step #1
If you are serious about using solar you need to walk around your house and look at ways to conserve. From the first day I moved in I have kept this in mind. This doesn't mean that you have to live like a hermit in the dark. If you drove by my house on any given night you would think I had a party going on. If I am awake almost every light is on with something going on in each room.

Conservation
Look at your lights. I use all compact fluorescent lights (CP light), which are still bright but save substantial power. For example, a CP light that equals a 75 watt bulb uses only 20 watts. I saved 55 watts of power, per bulb.

Look at your appliances. Every appliance I have bought from the refrigerator (propane), to the washer, to the wood burner (heat) are all Energy Star rated products. This simply means that they are designed to conserve power and natural resources. The government sets a standard and all Energy Star products have to exceed this standard to carry the Energy Star label.

Step #2
Once you have conserved. Dig out your utility bill. You want to find out the average amount of power you use each month. I average 575 kWh per month. kWh stands for kilo-watt-hours.

You will find a US map showing sun patterns. Simply compare the color of the region you live in to the colors of the charts below. This is how much a solar system will produce on average.

Step#3
Compare this information to your power generation goal, your roof size and your budget.

I live in Baltimore, MD. Based on my garage roof size and my budget. A CP24120 best fits my needs.

According to the chart this system will produce 296.5kWh per month on average. This is 51% of my electrical usage.

Step #4 Optional
If you are wondering how much power it would take to power 100% of your home, you can build a larger systems by using the small systems as building blocks.

This is just over my usage of 575 kWh. This means at the end of the year. I would pay nothing for my electric power.

Using this chart you can estimate how much power you use. The wattage for most appliances is listed on them. Just take the number of hours you use each item in a day and fill in the chart. Multiply the total watt-hours a day, by 30 and you will know estimated monthly usage.

LOAD	WATTS	QUANTITY	TOTAL WATTS	HOURS/DAY	WATT/HOURS/DAY
			watts x quantity		total watts x hours/day
Lights
Refrigerator
TV
VCR
Stereo
Hair Dryer
Microwave
Furnace Fan
Computer

Others

					Total Watt Hours/Day

The amount of solar you need to power your home is not dependent on the size of your home. The amount of solar depends on the amount of power you use in your home.

Look at you monthly bill from the utility company. It will list the total amount of power (kWh) you used in the last billing cycle. Divide this by the number of days in your last billing cycle. This will tell you how much power you use each day (kWh).

Yes, with the correct inverter you can safely sell power back to the utility grid. The real question is can I sell power back to the utility company. Most states have net metering bills that basically say the utility company will have to buy the power back from you at the same rate you buy power from them. The states that don’t have net metering bills typically only pay the wholesale cost of the power about 1-3 cents.

Until uniform codes have been adopted by all utilities it is best that you first check with your utility. Each utility has different interconnection standards that have to be meet before they will allow you to sell power back to the utility grid. The unfortunate thing about these different interconnection requirements is that modern inverters have all of the safety equipment built into them as standard components. So some of the equipment a utility company may ask you to add is already inside the inverter.

The safest way to figure out if you need a charge controller is to take Battery Amp Hour Capacity and divide this by the Solar Panel max. power amp rating. If the quotient is above 200, you don't need a controller. If the number is less than 200 than you need a controller.

For example if you have a 100 amp hour battery and a 10 watt panel, you take 100 and divide it by .6 (600mA) and you get 166.6. Since this is less than 200 you need a charge controller. If you have a five-watt panel in the above example you take 100 divided by .3 (300mA) and you come up with 333.3. Since this is larger than 200 you do not need a charge controller. However you still need a blocking diode, to prevent the battery from discharging to the panel at night. So as a general rule of thumb you don't need a charge controller unless you have more than five watts of solar for every 100-amp hours of battery capacity.

With a correctly designed PV system you can power almost any electrical load. However, as the load size increases the expense also increases. Loads like hot water heaters, air conditioners, room heaters and electric stoves should be avoided. The added cost of trying to power loads like these is very cost prohibitive. If these loads have to be powered it will be a lot less expensive to change the appliance to use an alternative fuel type like propane.

Very little. The solar panels may need a cleaning only if birds are a problem. If you have a flooded cell battery you should check you water levels once a month. If you have a sealed battery it will never need maintenance.

Yes. Solar is quite unlike a computer. If you start with a couple of good base components it is easy to add to your system later. First is to start with a good charge controller. Lets say you want to start with one solar module now. Don’t buy a charge controller that can handle one module. Buy a 20 or a 30 amp charge controller that can handle several modules. This will keep you from throwing away a small controller because you outgrew it. Most larger charge controllers cost less then two smaller charge controllers, so you will also save money.

The same principal goes for inverters. An inverter is a one time purchase. So think about what your needs will be in the future and buy something you can grow into. For example if you are looking at a 2500 watt 12 volt inverter. And you are using 80% of its power rating now you are not leaving yourself any room to grow. You may want to think about a 4000 watt 24 volt or 48 volt inverter. The higher voltages will save you in wiring cost but also mean you will have to add solar panels in 4 modules increments to make 48 volt.

PV stands for photovoltaic. Photo = Light and Voltaic = Electricity. A solar cell converts light to electricity.

A solar cell is made of silicon. Computer chips are made of this same material. Basically, when light strikes the surface of a solar cell some of it is absorbed into the silicon. This light energy bumps the electrons loose and causes energy to flow.

By packaging approximately 36 solar cells together a solar panel or a solar module is created. When you have more then one solar panels you create a solar array.

BOS stands for Balance of System. For a complete system you will need more then just a solar panel. Here is a short list of other components that might be required for your system.

If you have any questions about these components or designing a system please do not hesitate to contact us at any time.

Insolation Map Index
The numbers listed on these maps are the average worst case insolation hours. Insolation hours provide a way of predicting the output of a solar module at a specific location. This data has typically been gathered over a number of years from weather stations located throughout the world. For example, if you have an SX-60 solar module that produces 3.5A peak power in a location that has 3 hours of insolation, it can be said that the SX-60 will produce 10.5AH a day.

A word of caution. This insolation information should be used only for estimates. Solar systems should not have a final design based on this information. This map does take into account small climate changes and may not be 100% accurate for all locations. EcoBuildSupply has a vast resource of databases that have specific cities listed with accurate insolation data. Please allow us to verify any critical design before purchasing.

There are two major terms in battery wiring: series, and parallel. Parallel wiring keeps the voltages the same, while increasing the capacity. Parallel can be described as positive to positive, negative to negative. Here is an example of paralleling four batteries in a 12volt system.

Series connecting increases the voltage in a system, while capacity of the battery bank remains the same. Here is an example of series connecting four batteries together to create a 48volt system, and a 24volt system. Then paralleling the 24 and 48volt banks with another 24 and 48volt bank to increase capacity.

You may qualify for Federal and/or State Incentives, check out this site to see if you qualify:

This site will show links for both Federal and State Incentives……………………