Solar Power for Houses: Your Residential Solar Power System

There are a lot of jobs in Green Energy that are not the ones we immediately think of. In addition to the people climbing on the roof installing solar panels, there are salespeople, administrators, managers, clerks, lab technicians, engineers, scientists, communications personnel, and entrepreneurs, among many others.

The requirements for these jobs are usually the same as for their equivalents in other industries, with the addition of interest in and enthusiasm for green energy. Experience in the green energy industry is a plus but is often not required, partly because the green energy industry is growing rapidly and there often aren’t enough trained and experienced people available.

There are diplomas and degrees available in green energy, green buildings and other related fields. Many are certificates or diplomas rather than full degrees. These programs are often relatively new, and as the green energy industry matures it is likely that more people working in the industry will have some sort of certification specifically in green energy.

Green Energy Job Sites:

Green energy jobs online

Alternative Energy.com

This job requires tolerance of heights, strength to lift heavy objects
and knowledge of how to install electrical objects safely.

The pay is usually about 15 to 23 dollars an hour. The whole solar sector is a high growth sector of the economy, and job prospects are bright. A high school education is usually expected, along with some construction experience and an apprenticeship or trade school education. However, the exact things employers look for vary somewhat. I culled the list below from actual job ads:

Things employers look for when hiring solar installers are:

• Ability to lift heavy objects (approx. 30-50lbs)
• Ability to work in a variety of positions
• Ability to work in hot sun and awkward spaces
• Not afraid of Heights
• Ability to interact with clients
• Attention to detail
• Ability to keep records and understand documentation
• Driver’s license and clean driver’s record
• Construction-related experience

Knowledge of Computer Software, OSHA safety regulations, and ability to understand blueprints is also often required.

Sources:

SolarInstallerjobs.com

A Day (or Three) in the Life of a Solar Installer

Places Hiring Solar Installers:

Standard Solar

SolarCity

Rec Solar

Batteries are an important component of off-grid and many grid-tied residential solar power systems. They are used to store excess electricity produced by the photovoltaic panels for times when they are producing less electricity than needed, such as at night. Batteries are used in both off-grid applications and in grid-tied battery-backed systems. Batteries for off-grid are usually sized to last through normal use on three cloudy days.

The batteries in grid-tied residential solar power systems are used for backup when the grid goes out. There are usually fewer batteries in these banks because they are only used for backup rather than being used every single night.

The three main types of solar batteries are all lead-acid batteries. However, they are very different from the batteries used in a car because they are deep cycle batteries. This means that they can be drained much more deeply of their charge than shallow cycle batteries such as those used in cars. Car batteries will not stand up to the strain that a residential solar power system will place on them.

Batteries Suitable for Residential Solar Power Systems

Flooded Lead-Acid Solar Batteries

Flooded lead-acid batteries are the cheapest type of lead-acid batteries commonly used to store solar power. They also have the longest life, but require regular maintenance. Distilled water must be added as necessary to replace that lost during charging, and because they are not sealed they must be kept clean and there is a danger of spillage.

Absorbed Glass Matt Sealed Lead-Acid Solar Batteries

These are sealed, and therefore do not require regular maintenance as flooded lead-acid batteries do. They are a newer invention and so far less widely used than flooded lead-acid.

Gelled Electrolyte Sealed Lead-Acid Solar Batteries

These are freezing resistant and are typically used in unheated spaces. They must be charged slowly in order to avoid decreasing capacity, making them better for grid-tied backup than for off-grid uses.

Sources:

Homepower.com

Solar-Batteries.net

The less power you use, the less expensive the home solar system you will need to power your home.   Increasing energy efficiency is a great way to do this.   Recent appliances are more energy-efficient than older ones but the extent of the energy savings varies greatly between different types of appliances.  The two most energy-intensive appliances in most homes are refrigerators and dryers.

Why You Need an Energy Efficient Refrigerator

Refrigerators use a lot of energy.  New refrigerators use a lot less energy than older refrigerators.  There is also a great difference in energy use between different refrigerators.  The standard advice is to buy a new energy efficient refrigerator if your current fridge is more than 10 years old, as the energy savings will pay for the new refrigerator.

New Energy Star refrigerators use 50% less electricity than the average ten year old refrigerator.   If you live in BC, BC Hydro runs a fridge buy-back program in an effort to reduce electricity use. EnergyStar is a program that certifies energy efficient appliances.   If you live in BC Canada, BC hydro has rebates for buying EnergyStar appliances.   Many other areas probably have similar programs.

Well-maintained appliances are more efficient than poorly maintained ones, as well as doing their jobs better.   If you cannot afford to replace an aging appliance, performing regular maintenance will help minimize its its electricity use.  This will not reduce electricity use to the level of a new appliance, but it will reduce it greatly over a poorly maintained one.

Energy Efficient Dryer or Clothesline?

Dryers use a lot of energy, sometimes as much as the refrigerator despite the fact that they aren’t on all the time. Ideally, one would hang clothes to dry outside, thus using no electricity at all, but in many places this is inconvenient in the winter. Clothes will dry in the cold, but not if it is raining on them.

Drying outside is against bylaws and home owner association regulations in some places. Do be aware that many of these regulations are being challenged and declared illegal, so if you want to dry outside you may be able to do so even if you weren’t a year ago. The movement to make anti-drying regulations illegal is often referred to as the ‘right to dry’ movement, and it is widespread.

Indoor drying racks also work, but do take space while the clothes are drying.  The most inventive indoor drying rack I’ve seen was hung from the ceiling of a kitchen and hauled up and down with a rope and pulley system.  This made extremely efficient use of space and allowed a washer’s worth of clothes to be dried indoors in Britain in the winter.  It worked well enough that the house did not have a dryer.  If you have a small household that does not produce huge amount of laundry this system could well work for you.  It is it is hard to get more electricity efficient than this!

If you do want a dryer, an energy-efficient dryer will save on electricity, although not as much as letting half of each load air-dry.

Energy Efficient Clothes Washers

Front loading washers are more efficient than top loading washers.  If you don’t have large amounts of laundry, a compact washer will save you electricity.  If you do have large amounts of laundry, a full size front loader may be your best bet, as doing one larger wash takes less energy than doing multiple smaller washes.  Some dryers are more efficient than others, so pick an efficient one.

Energy-Efficient Dishwasher or Handwashing?

An energy-efficient dishwasher that is fully loaded uses less hot water than hand washing.  However, this requires that you load it fully.  If you only ever wash small loads at once, hand washing may be more efficient.

There are also energy efficiency improvements to be found with cooking appliances, but they really deserve an article of their own.

There are three main types of solar panel for sale at present: monocrystalline, multicrystalline, and thin film panels. A fourth, sometimes known as vaporware, is sometimes mentioned in the media, but does not yet exist. There is no one best solar panel for every purpose, but each type of solar panel has its own advantages and disadvantages.

Monocrystalline Photovoltaic Panels:

Pros:

• Most efficient, especially in low light conditions
• Less space required for the same amount of power
• More durable than Thin Film

Cons:

• Most expensive per watt
• Production process uses more silicon and more energy
• Rigid

Polycrystalline/Multicrystalline Photovoltaic Panels:

Pros:

• Lower price than Monocrystalline
• Higher efficiency than Thin Film

Cons:

• Higher price per watt than Thin Film
• Rigid
• Lower efficiency than Monocrystalline

Amorphous/Thin Film Photovoltaic Panels:

Pros:

• Cheapest per watt
• Can be made flexible
• Harder to break
• Uses less silicon and less energy during manufacture

Cons:

• Degrades faster
• Lower efficiency
• More space required to produce the same amount of electricity

Vaporware?

This doesn’t actually exist yet, but if it ever does, it will be photovoltaic material that you spray onto a substrate which then becomes a photovoltaic panel.

In Practice:

The type of application has a major impact on which type of solar panel is best for you.  If you want to have solar panels on a backpack where the panels have to be flexible, your only choice is Amorphous/Thin Film panels.  However, if you require the largest possible amount of electricity from the smallest area of solar panel and do not care about it being flexible, then Monocrystalline photovoltaic panels are best.  The choice is up to you.

For More Information:

Northern Arizona wind and sun

Solar Sphere

There are now many types of portable solar equipment available.  They range from the truly gimmicky to the sensible. From hats with a solar panel and fan for cooling your head to  solar powered calculators and portable solar charging systems.  Keeping track of what’s out there can be a challenge.

Portable Solar Devices:

Some of the solar powered items for sale on the Internet include halogen lanterns, hats with fans, Christmas lights, radios, portable refrigerator/freezers, battery chargers, bags, outdoor lighting of almost every description, rodent repellers, children’s toys and others.  Examples of such things for sale can be found at solarhut.com, as well as many other places on the internet.  Many solar objects are new designs or are being made by companies without a long reputation in the field.  This means that while there is a wonderful selection, the quality is rather variable.

Portable Solar Charging Systems

Portable solar charging systems are much more practical than they used to be.  Many of them make use of technologies like thin film photovoltaics so that they can be folded up and packed away when not in use.  For people like backpackers, this means that you can stick your solar panel in your backpack and have power wherever you go.  There are also battery chargers that are part of bags or backpacks.  A review of such an item can be found on treehugger.com. On a somewhat larger scale, solar panels are also used on boats and RVs to power appliances and charge batteries.

Solar thermal and solar photovoltaic power are similar in that both use the sun as an energy source, and both are renewable. However, there are quite a few differences between them, including price, type of energy output, and the things that energy can be used for in your home.  The table below should give you a good idea of the pros and cons of both types of solar power.

Prices are global average for July 2009 and are US denomination. They exclude rebates your government may give. They assume the system is grid-tied.

http://www.solarbuzz.com/solarindices.htm

Solar pool heaters are the most common use of solar thermal technology in North America.   This is because they are extremely cost effective: a solar pool heater will typically pay for itself in 2 to 3 years (Can. Solar Industries). Even without considering the savings in greenhouse gas emissions, solar pool heaters make a lot of sense.   The total price of solar heating a pool is usually $3,000-$4,000 US including installation, but can range from $2,500 to $7,000 US (Costhelper.com).

Solar hot water panels used in pools are flat plate collectors. They are usually made of rubber or black plastic and are a very simple use of solar thermal technology compared to solar water heating systems for drinking water.

The solar hot water panels are usually about 50% of the pool’s service area.  If a pool is indoors or is not in direct sunlight, a larger area of solar heating panels must be used to reach the same temperature.   A pool cover should be used at night to reduce heat loss.  If you don’t use a pool cover, you’ll need to install twice the area of solar hot water panel.

While solar pool heaters make excellent sense for swimming pools, they don’t work as well for hot tubs.  The water temperature can be raised high enough using metal collectors used for heating domestic water, but if the jets in the hot tub are used, the water will swiftly cool down again.

Sources:

Canadian solar industries association.  Solar pool heating overview.  Retrieved June 20, 2009

Costhelper.com

Residential solar pool heating systems: a buyer’s guide 2001 retrieved June 20, 2009

In climates where there are freezing temperatures, the water in solar hot water panels is in danger of freezing.  No hot water is produced when this happens, and it’s possible that the panels or piping could be damaged when the water expands as it freezes.   However, it’s perfectly possible to get solar  hot water in a cold climate – even during the winter.

The most common way to prevent the solar hot water panels freezing is to use glycol-based solutions in the panels. This requires a closed loop system where the heat is transferred from the glycol solution into the water you use in your house via a heat exchanger.   These systems are more expensive than simpler systems, but they are much more resistant to freezing and can continue to produce heat through the middle of a cold winter.   You will probably want a tankless hot water heater as backup because they may not produce enough for your needs when there are long spells of cloudy weather, but they will still produce hot water.  Both active and passive heaters can be outfitted with glycol so long as there’s a closed loop system.

Four-Season Solar Thermal Systems

Glycol-based solutions are typically used in active solar thermal systems, but they are also used in some Thermosyphon systems.  In order to use glycol in a Thermosyphon system, it must be a closed-loop system in which the solution in the solar thermal panels does not mix with your household water supply.  The glycol acts as antifreeze, preventing the pipes from freezing.  These solutions are typically 50/50 glycol and water.  Active glycol systems tend to be expensive, but they are considered the best choice for very cold climates.

There is one type of water-based system that can be used in frost-prone areas.  This is the drainback system, which does not easily freeze so long as the piping is sufficiently inclined so that drainback can occur quickly.  However, I suspect that this system is less tolerant of extremely cold temperatures for long periods of time than a system that uses a glycol fluid.

Three Season Solar Hot Water Systems

It is also possible to use a very simple system such as the batch heater during the summer and drain it during the winter.  You will get no hot water from it in the winter, but it should still be usable the next summer.

As you can see, there are several choices of thermal hot water systems for homes in a cold climate. Whether active or thermosyphon glycol, drainback or summer-only batch, there is probably something available that will fit your needs and pocketbook.

Sources:

US Department of Energy. Energy Efficiency and Renewable Energy. Energy Savers: Solar Water Heaters. Retrieved June 19 2009

Homepower.com. Retrieved June 19 2009

Build it Solar: solar water heating. Retrieved June 19, 2009

To create hot water using solar thermal energy, the sun’s heat is used to heat water directly without converting it into electricity.   The most common use of solar hot water in North America is heating swimming pools, but solar thermal’s potential goes far beyond this.

Solar thermal is commonly used for water heating and for heating houses.  The cost of heating by a solar thermal system is usually lower than the cost of an equivalent amount of electricity supplied by photovoltaics because solar thermal is on average 3x more efficient at converting the sun’s heat into energy, although the savings depend on the type of solar thermal technology used.  Solar thermal systems are also low maintenance.

Types of Solar Water Heater

1) Collector (solar hot water panel) Types

There are three main collector types: flat plate, batch, and evacuated tube.  Evacuated tube technology is generally more expensive than flat plate and batch because it is mechanically more complicated.

2) System Type: Passive or Active

Active systems include a pump; passive systems do not.  Passive systems are less expensive and may be more reliable but are less efficient (Energy Savers: Solar Water Heaters).

Passive Solar Water Heating

Batch Heater

A batch heater is the simplest type of solar water heater available.  They are also sometimes known as breadbox heaters, since the tank of water on the roof is often about the size of a breadbox.  If you wish to build your own solar hot water system, a batch heater is probably your best bet.   Being water-based, they are not suitable for winter use in climates where freezing weather can be expected.  They also have the disadvantage that hot water cools overnight and usually isn’t hot early in the morning.   The Florida Solar Energy Center has a free set of plans and instructions for building one, which can be found here.  They give the materials cost as being US $70.00.

Thermosyphon

This design tends to be more expensive than batch heaters.  However, because there is an insulated storage tank hot water is available at all times of the day or night, unlike the batch filter.  This design is actually the world’s most popular solar water heater (Homepower.com).  It may be closed loop or open loop.  If it is a closed loop system, glycol can be used.  This modified design is suitable for using in climates with freezing temperatures.

Active Solar Water Heating

Drainback Heater

This type of heater is more complex, being a closed loop system where the water in the collector does not mix with the house’s water.  A heat exchanger is used to move the heat from the liquid in the collector to the house’s water.  Like most active systems, it is more expensive than a batch heater.  On the other hand, this system can be used in the winter in climates with freezing temperatures if the pipes are adequately sloped to ensure drainback occurs quickly.

Glycol-based Solar Thermal Systems

Systems containing glycol are primarily used in areas which have freezing temperatures during winter.  This is because they continue to work and provide hot water during such weather, unlike most systems that use water.  Water-based systems may also suffer damage when the collectors freeze that will then need to be repaired.  Glycol-based systems are more expensive than systems that use water, but in a cold climate this disadvantage is outweighed by their resistance to freezing (Homepower.com).

Overall, solar thermal hot water is a technology that is economical to install and run by renewable energy standards and can be used almost anywhere.  It has excellent potential for home use and should be perhaps the first alternative energy technology considered by a homeowner wanting to reduce dependence on the electricity grid.

Sources:

Build Your Own Solar Batch Water Heater. Florida Solar Energy Center Retrieved June 12, 2009.

http://www.builditsolar.com/Projects/WaterHeating/FSECFS36Batch11349.pdf

US Department of Energy. Energy Efficiency and Renewable Energy. Energy Savers:Solar Water Heaters. Retrieved June 12 2009

http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12850

Homepower.com

http://www.homepower.com/basics/hotwater/