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FAQ's on Solar Power

This a list of hypothetical questions designed to cover topics helpful to those considering solar power options, and the sutiability of solar power in their circumstances. This page is dynamic, so as people ask questions the content will change. It will also need to be broken out into smaller and more specialized sections as time goes on.


Contents: 

How Do You Plan A Solar Power System?

 

Planning a Solar Power system is extremely important. It requires thinking beyond your current needs so that future expansion doesn't require you to rebuy and redo unnecessarily. If you can anticipate your future needs you can usually find ways to ensure that the equipment you buy will fit neatly into your future plans.

Conservation of electricity is paramount. The less electricity you use, the less you need to generate. You want to use efficient lights and appliances that will allow you to live comfortably and safely without comprimising your quality of life. Live well, be efficient!

The first step is to systematically determine how much power you want and need. Some appliances use a lot of power (like a toaster) but are used a very short time and as a result use a small amount of power each day. Estimate the power used by each device and the hours each day that each device is operated. Multiply hours used by the power used, and by adding these totals you will have a good idea as to what you'll need. This can be an eye opening exercise!

The next step is to determine what power resources are open to you. Do you have sufficient wind to use a wind generator? Do have space and southern exposure for solar panels? Is there a source of water power available? After considering these issues and a little research you'll be able to build a plan for building a solar power system. Remember that a combination of energy sources is often the wisest approach.

Be sure that you include sufficient battery capacity to get you through uncooperative weather, or other emergency conditions, and plan on a battery condition monitor you can see easily from in your house. This is very important! Out of sight can be out of mind, and you can be unaware of battery condition and the stress on your batteries if you can't easily monitor them. (We destroyed a set of batteries this way, and I can tell you that metering is a very important part of your system!)

The ideas included in this FAQ's section is designed to help you plan your power requirements, and balance your requirements with conservation and the power resources available to you. Your solar power installation will be uniquely yours. Your own private solution based on personal priorities, physics, and personal economic realities.

Why Do People Choose Solar Power?

 

There are number of different motivations for choosing solar power over public utilities. It's usually a lifestyle choice driven by economic considerations and ideology. Here is a summary of reasons that illustrate the wide range of considerations that make solar power attractive. Tell us if your reasons are not on the list.

1. Installation cost. 

In many locations (like where we live), the costs to get a line to our house is very high. In fact, in many places the costs are so high that it is simply out of the question to bring in commercial power. In our case we would rather spend the $16,000 on our own system then give it to the power company.

2. A feeling of independence. 

Once your system is installed and working properly, the costs drop to an extremely low level. Maintenance is minimal and usually under your control. Instead of being locked into a straight jacket of rigid monthly installments (I'm referring to minimum installments or guaranteed payments contracted with the utility to get new service) you can adjust to your energy system investments to match your income.

3. A hedge against inflation. 

Energy costs are increasing dramatically, and the only way to protect yourself from these increases is to pay for your future energy needs NOW! Increased energy costs will guarantee inflation from which none of us is safe. Remember that vitually all of the goods and services we currently rely on have an energy cost built in. The Carter years are a perfect illustration of our dependence on cheap oil, and the results that follow as a result of increased oil prices beyond our control. Remember double digit inflation??... If you consider our vulnerability and reliance on cheap energy, I think you'll see that as an investment in your future, going solar is a risk reduction investment that is hard to beat.

Can I Live A Normal Life?

 

When I first considered alternative power I envisioned a primitive lifestyle. It seemed that it must be difficult, expensive, and a lot of work. I was amazed at how simple it was to get set up with a good starter situation, and we have all the 'comforts' we'd have if we lived in town.

Almost all the compromises have been minor, and now they seem irrelevant. Most of these so-called compromises would be more correctly described as differences. We live better now than we did before switched, and we waste far less power.

Change can be scary. However, in the case of solar, the fear is unfounded. We have proven to ourselves that going solar independent is both practical and cost effective. I encourage everyone to go solar. If you do so you'll be glad that you did!

Can You Go Solar Gradually?

 

First you need to think about your power needs and your future requirements. Then, based on your resources you begin to put in place the planning steps/goals necessary to accomplish your objective.

Network yourself with others with similar interest. Subscribe to HomePower Magazine, Backwoods Magazine, or any other publications along the same vein. Look for books on solar power and glean from them information you'll need.

Lay a foundation in your mind that will give you a solid reference system to make decisions with. Look at what others have done. Many showcase solar homes are so exotic and expensive that they can be demoralizing. Don't allow these things to deter you. Even these monuments of impracticality have ideas implemented that you can put to work.

Keep an open and practical mind. Great ideas can be found in the most unexpected places. take the time you need to get where you want to go. Some are retiring or have the proceeds from the sale of a home that allow them to go first cabin all the way. If this is the case with you then congratulations! For most of us it will take a little longer to get the job done.

Is it Smart To Leave The Grid?

 

Many people are at first a little worried about cutting the umbilical cord between themselves and their utility company. We grow so accustomed to having services provided for us that we get the idea that we can't do these things for ourselves. The truth is: It's easy! And interestingly enough your power may be more reliable then ever.

I used to dread electrical storms, since the power could go out at any time, and a nearby strike to a power line could be guided right into my home, doing some very nasty things to my computer system, TV, etc. However, power outages were the biggest concern.

Now, I have power that is FAR more reliable then I used to get from the local public utility. Yes, lightning strikes are still a possibility, but at least I don't have a long piece of wire up in the air, just begging for the opportunity to guide destructive power into my home.

The information here is designed to help you in planning your migration from dependency to energy independence. My experience has been that the change is easier then you might think.

How Do You Take Inventory of Your Resources?

 

Power Resources 

The first step in energy planning is to assess the resources and options open to you for power collection. What works for your neighbor may not work for you.

Water Power 

is the least expensive resource. If you have enough 'head' (height of drop), water flow, and the flow is reliable you've got it made. Water flows 24 hours a day and even a small water turbine can produce a lot of power during a 24 hour period. With a battery bank to provide an energy buffer for high peak loads, you have an attractive energy situation.

Wind Power 

can be a very inexpensive resource depending on the wind power available to you. Wind maps can provide a clue as to the average wind speeds in your area. I understand that many states (California is one) can provide this information. Wind power available at your specific site can be disappointing or a pleasant surprise. Measurement with a data logging anemometer is well worth the cost if your site is marginal.

Even if you know you have sufficient wind, properly sizing your wind system can save you a lot of money, decreasing the time it takes to return your investment. For more information on sizing your wind system, be sure to read our technical information page. We have information there which could be of help to you.

PV Solar Panels 

are what most people first think about using solar power. They are noiseless, reliable (20 years or so), and have no moving parts to wear out or fittings to grease. Except for periodic inspections of electrical connections, and other installation specific issues, there is no maintenance. The only problem is that you need an unrestricted path of sunlight to your panels, and that means weather is an issue. The weather bureau can supply information to help you determine the average hours of sunshine for your location. Clouds are your enemy, but I've been pleasantly surprised as to how much power we get on an overcast day. Light is the key, and Light=Power.

Generators 

Every system design should include one of these evil and nasty devices ;-) It might seem to break the paradigm of living independent, but it's often the first purchase you should make while you put the rest of the pieces of your system together. Elsewhere (on a page devoted to generators) I'll discuss generators in agonizing detail, but just keep in mind that the generator is a key safety net that you will need to have around incase of uncooperative weather, electronics failures, maintenance issues, and equipment that uses an abusive amount of power. Eventually you might hardly ever need it, but at the start it might be very important.




Use a Combination of Sources! Don't focus your attention on a single solution. Combine your energy assets into a system of energy sources if you can.

Locally sunshine is plentiful, but the wind blows when the sun is hidden by clouds. We're installing a 50/50 combination of wind turbines and PV panels. Since 5kw/day is what we need, and 10kw/day is what we want, we're starting by installing a 3kw wind turbine and a 1kw/hr hour solar panal array.

We have 5.66 hours average of sunshine per day (worst case, in December) which equals 10kw/day. At 8mph average wind speed (pessimistically) we should get 5kw/day from the wind. The combination should yield 10kw/day and seldom should we drop below 5kw/day. Notice that these calculations exceed the targets, so that recharge losses and other electrical losses are taken into consideration.

Another advantage of using wind power and sun, is that you will often have charging going on nearly 24 hours a day. This reduces the depth of discharge on your battery system, helping them to last a lot longer, saving you unnecessary expense.

If you have water power as an option you can add that to the mix and even if it is insufficient as a sole source, when combined with these other options it can become an important part of the whole solution.

On another page I'll discuss batteries. A very important area that you will need to understand.

Why Is Conserving Power So Important?

 

Most of us are very used to being wasteful with electricity. It's a habit that you can't afford, and when you start looking at your household energy needs, you see ways all around you to minimize energy consumption and maintain your quality of life. Saving energy doesn't mean austerity.

The less energy you consume, the less energy you need to collect, store, and convert for typical household use. Here's a list of typical steps you can take to reduce your energy bill and stay comfortable. These are not requirements, just typical solutions that people 'off the grid' use to stay 'comfy', and scrimp on energy at the same time.

  • Use a wood stove for cooking and heating.
  • Use propane for cooking and heating your home.

    In both of these cases fuel is storable, usually economical, and no electricity is required. We use a propane heater in our home made by 'Cozy', which has a wall mount thermostat that uses a thermo-pile to create the energy required for the thermostat to work. It maintains our house at a constant temperature without fans, electricity, or physical effort. It really works well!

  • Hot water is usually propane, but solar heat collectors for hot water are readily available and very effective. 'On Demand' hot water heaters can raise the temperature as needed if your solar heat collectors aren't large enough or there isn't enough sunshine to furnish sufficient thermal energy.
  • Super efficient refrigerators keep the food cold or frozen while consuming but a fraction of the energy a normal fridge uses. You can choose propane or electric. We like our Vestfrost electric fridge, and it has really worked out well for us.
  • There are new lighting technologies to choose from now that are more reliable, produce more light, and last much longer. These new lighting options offer considerable savings on the amortized cost of the bulb, and offer considerable savings in energy consumption.


I know a family that uses over 1 MILLION watts of electricity a month (in fact many people do!). We use about 150,000 watts (we could cut back much more) and the difference in energy use makes a huge difference in the feasability and cost of solar power. Collecting 5,000 watts a day is not extremely difficult, but collecting 33,000 watts a day is a different story.

In addition to the costs of collecting solar power there is the cost of storing power for bad weather days. These costs are also dramatically reduced with conservation.

The point of this discussion is to illustrate that Ben Franklin was right when he said, "A watt saved is a dollar earned." (or something like it). When you plan your solar system. plan on having what you need to live comfortably, but not wastefully.

Our system here will break even in about 5 years. In the mean time I'd like to keep some money for other things! The more stress you put on your finances the more difficult it is to enjoy the 'free' electricity you'll collect every day. If you're not having fun you're not doing it right.

I suggest you install a minimum configuration initially, and each year after add capacity and improve your system. Save every watt you can, so that a minimum configuration is enough and to spare.

What Are My Lighting Options?

 

Efficiency is a word that can save you big money when you move off the grid. You want to be aware of the energy costs associated with your purchasing decisions. You can usually get what you need, and live the way you would like, and still cut your energy consumption drastically! The less energy you need, the less you need to store, the less energy you need to collect, and the less you need to spend. Be efficient. It pays. 

There have been a number of exciting efficiency improvements in lighting that fit beautifully in a solar home environment. Most of the new lighting options are designed for 120 VAC, but a number of these are also available in 12VDC, and 24VDC configurations. 

DC or AC Lighting

 

DC lighting has the following advantages: 

  • 1. Reduces the size and cost of your AC inverter system.
  • 2. Can increase lighting efficiency.
  • 3. DC versions can last longer than AC lighting.
  • 4. Your inverter can remain in low power standby mode more often.
  • 6. You can easily convert auto 12v lighting for home use, which yields some really nice lighting options for zone lighting for desk and counter tops. Walkway lighting systems are now quite popular and are usually 12vdc systems.


    Disadvantages of DC include: 

  • 1. More limited lighting choices.
  • 2. Rewiring of prexisting lighting electrical system could be required.
  • 3. Higher installation costs due to lower volume production of DC lighting systems.
  • 4. Large, more expensive wire is needed for low voltage systems.


AC lighting can usually be converted to DC and work very well indeed. This way you can still buy the fixtures that you like and that are readily available, and gain the benefits of low voltage DC lighting.

The are a number of different types (or technologies) of lights that are available. The largest categories, and their strengths and weaknesses include:

Incandescent

These are the venerable 'light bulbs' that we have grown accustomed to. They produce a warm light, are available in a variety of shapes and styles. You can buy them anywhere, and they are the least efficient option you have. They make better heaters than light producers, and they have limited life. Not a good choice unless you have power to waste, or needan emergency replacement until you can get a better bulb in place.

Auto parts stores often carry 12v bulbs with a standard screw in base for drop lights. I've even seen DC bulbs once in a while at large grocery stores for appliance use. 24V bulbs are commonly used by the boating community, and can usually be found somewhere locally and can always be found by mail order.

There are places where the light bulb is a very good choice. Such as in an unheated shop or garage where it gets very cold. At low temperatures more efficient lights won't start. A porch light can be an important safety feature, in below zero temperatures incandescent is hard to beat.

Halogen

These are constructed very much like an incandescent bulb, but have a small amount of halogen in the bulb that increases the efficiency and extends the life of the bulb. Although these are a better solution than the traditional light bulb, there is a much better approach I'm going to discuss next. Since these bulbs operate at higher temperatures they will be destroyed by water drops hitting their surface, and they might destroy a light fixture that has poor airflow around the bulb.

Flourescent

This is the best choice choice there is right now in lighting. Though there is nothing new in the basic lighting technology, the flourescent light has been repackaged to fit where old fashion light bulbs have always reigned supreme. There has also been efficiency gains made in ballast design. New higher speed digital switching ballasts result in lights that waste less power and due to the high speed switching increase the light output of the fourescent coating in the bulb. This bulb is available in DC, and almost always has the higher speed ballast which means more light per watt. There ae also DC ballast kits that you can use to retrofit traditional fixtures for DC.

Mercury Vapor and Sodium

I've noticed a few sources for mercury vapor lamps that are suited for driveway lighting applications available for DC. This is the highest efficiency type of lamp you can get (except for sodium) but it's color spectrum is not acceptable for interior home use. I mentioned sodium, but it's yellow light is really annoying and it is a high voltage only option. Sodium is not recommended.

What About Heating and the Kitchen?

 

Home Heating Systems

Harvesting electricity from sunlight is expensive enough that it isn't practical to use electricity for heating. Since heating your home in winter requires a lot of energy most people use propane or wood for heating and cooking. Propane use can be minimized by using it as a backup system and using wood as a the primary fuel of choice. 


Solar Heat Collectors

Heat from the sun should be provided by solar heat collectors for hot water and/or home heating. Heat collector systems are a great way to preheat water to reduce your need for propane or wood for domestic hot water use.

Hot water heating systems can be used to heat your home, but this can easily become an expensive proposition in very cold climates. You need the most heat at a time when you get limited sunshine and heat losses of the system are nearly at their peak.

Choices like this need to take into account your climate and your needs. Like many choices what's right for you is going to different for someone else. 


Home Cooking

Most people in this area use wood for space heating, and use propane for cooking. Many high quality wood cooking stoves are available, so there are many good options here.

Refrigerators, and Other Cool Options

 

Propane Refrigerators

Not too many years ago, full size refrigerators and freezers were available from any propane dealer. Now the choices are far more limited. High quality units design for the RV market are available, but they are smaller than most of us would prefer.

The advantages of propane include:

  • 1. Super quiet operation
  • 2. Propane is an economical and storable fuel.
  • 3. No moving parts. Excellent reliability.

Solar Electric Refrigerators

Until recently propane was the fuel of choice, but now there is another set of choices you can make. A new breed of extremely efficient electric refrigerators are now available, that make using solar electric power an attractive alternative to propane.

The advantages of new generation electric fridges include:

  • 1. Less energy consumption.
  • 2. Reduced heat released inside the home.
  • 3. Better temperature regulation.
  • 4. More internal space.
  • 5. No propane fuel costs.
  • 6. Excellent reliability.

How Do I Start Building My Solar Power System?

The following pages are designed to give you examples on how people typically build their solar power system, and ideas you might find useful.

Start and continue to work where you have the greatest need, and over time you'll get where you want to be. "By the inch it's a cinch, but by the yard it's hard." Don't quit!

Converting a Home to Solar



In our case the 'summer cabin' we purchased was plumbed and wired for electricity. From lack of use the home was very nice inside. There was no well or electricity run to the home, but there was a septic system in place, and there was a gas generator that was used by the owners when they came for the weekend. We found a place that was all ready for the solar touch. It came with an RV propane fridge, and a propane stove and water heater.

The first purchase we made was a Trace DR2424 inverter which has been really super. It has run for 24 hours a day for the last year or so without a whimper. Initially we bought a small bank of deep cycle batteries and the generator is used twice a day to charge the batteries.

We drilled a well and we have very good water. The water is 80' down (we were very lucky) and the well pump is 160' down a 183' shaft. We have a good capacitor start 3/4 hp 240 volt AC pump. I used a transformer to raise the 120v output of the Trace inverter to 240v, and it worked out nicely. If we want to do any serious watering we need to run the generator while watering.

Now we had power 24 hours a day! The cost of fuel to run the generator dropped drastically and the lifetime of the generator greatly extended. We were in business!!!! Our electricity expenses were >$80 per month for electricity when we lived in town. The financial expense is for gas instead of a power company, but we were off the grid and loving it. Our power has also proven to be more reliable.

Our neighbors were without power for 20 hours this winter. One fellow had a generator, but most were out of luck. We might not of known there was a power outage if it hadn't been for a phone call.

We've since purchased a DR3624 which works much better for very heavy loads and is a real bargain in watts/dollar. We will use two of these in a stacked configuration to run the deep well pump. We tried to stack the DR3624 with the DR2424 and found out that although the two worked very well together in producing 240v and the water pump loved it, the charging circuits of the two units were not compatible. This problem might be solved by splitting the battery bank so that each charger was working into a seperate battery set. I'd like another DR3624 so I'll wait, and just use the transformer to step up the 120v from the DR3624 I already have to run the pump.

We are now ready to install solar panels and wind turbines. We are currently upgrading our battery system, and converting light circuits for 24v DC. 




We intend to set up a 1000 gallon propane tank in the fall. The current 500 gallon tank had to be filled once in the winter and it's hard for the delivery people to get to our place in winter. The larger tank will mean we need no gas deliveries in winter. Propane prices are cyclical and if you have to buy Propane in January you have to pay dearly for the privelege. By having enough storage capacity you can buy in the fall when prices are still sensible and then in the spring when prices have come back down. The larger tank should easily pay for itself over time.

Our home has a good wood stove, but we use propane for heat at night or when we feel lazy, or when we want to leave the house for a while.

We replaced the little RV fridge with a VestFrost 16 cu ft electric that is super efficient. It reduces the demand for propane and has a lot more cold storage capacity. It regulates temperature with extreme accuracy, and we want to get another with the doors opening the opposite way for a full 32 cu ft of side by side fridge and freezer.

Now you might be wondering why we would use an electric fridge. The reason is that eventually, we see using propane only as a backup fuel. We will have enough solar powered electricity generation to meet our needs easily. We are going to wait until we get the rest of the system in before we get the other fridge. The propane fridge works on a constant heat cycle principle. This means that a flame is burning all the time, putting extra heat in the home all the time. The summers here are hot, and we don't need the heat inside. The RV fridge is also not efficient and not designed to be used for a household. There was a time when full size home propane refridgerators were common, but not any more.. I think it would be a popular item, but I suspect that if it weren't for RVs there wouldn't be any propane fridges made.

Batteries for Solar Power Installations?

 

This is an area where you really don't want to compromise. The surest way to build a system that isn't cost effective is to use the wrong type of battery, not enough batteries, or to treat the good batteries you buy improperly. 

These mistakes can be avoided, and there are many good books available that can help you understand the principles involved. We'll outline a few guidelines here that can make a big difference to you, and more will be added as time goes by so keep checking in....

When you plan your battery system there are a few guidelines than be very helpful. Here is a short list:

Battery Considerations

  • Expected power requirements per day in amp/hrs
  • Expected useage (a few days per month or every day)
  • Maximum current demand
  • Desired lifetime of the battery system
  • Monitoring System desired to track battery system condition

How Big a Battery Bank??

Occasionally the sun and the wind will fail to provide sufficient power. When this happens your battery system must be large enough to provide all the power you need until the weather starts cooperating. The typical rule is to provide 3-4 days of power. If your daily need is 200 Ahrs, then you would want an 800 amp hour battery system. This is a typical battery bank size in use by those who continuously depend on their solar power system for daily living. A larger battery is often a good idea, but I advise not going higher than 10 times your daily requirements unless you have an unusual power requirement that necessitates a huge battery system.

If you are setting up a 'getaway retreat' that is used once or twice a month, your average power requirements are much smaller and you can probably get by with a battery bank capacity only twice your normal day of useage. Your solar panels can be very low power since there is plenty of time for your system to recharge before your next visit.

How Long will the Batteries Last? The longevity of battery systems vary widely. Cheap deep cycle batteries like 6V golf cart batteries, may be the lowest cost way to go in the long haul. Generally considered to last 2-3 years, this choice would mean that you would need to change them more often, but they are inexpensive so the trade off is longevity for lower cost. High priced batteries often need little or no maintenance and may last more than 20 years in demanding service.

One of the biggest factors in long life is monitoring your batteries so that they are not discharged too deeply. All batteries will last longer if they are discharged <= 25% before recharging. A battery might specify 80% as maximum discharge but this deep discharge shortens the life of your batteries.

Very high current demands from a small battery bank can cause severe stress to your batteries, even though the amp/hrs used is small. This is another case for a large battery capacity.

Unusual stress can also be placed on your battery system by charging at an excessive rate in relationship to battery bank size. A large wind generator system can charge at 150 amps at 24 volts. This means that you would want a large battery bank so that you can absorb these huge charge currents without excessive gassing. 10 times the maximum expected charge current is a good rule of thumb.

Over the life of your battery system the maximum voltage and apparent capacity will fade. This is normal aging and will always occur. Proper maintenance and minimizing the battery bank's work load will extend battery life considerably. One very good thing is that although the batteries will eventually become useless the aging process is gradual, giving you months or more warning before replacement is required.

This page will be added to and expanded to provide as much information as possible help you in this important area. Be sure to email your questions to us so that we can tailor information to cover things that we might miss, or gloss over issues that might need to be covered in greater detail.