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How to Harness the Sun

Harnessing our sun’s solar energy

There is but one sun in our solar system, but there are many, many ways to harness its power.  Plants harness it via photosynthesis, giving off oxygen for us to breathe, and food for us to eat.  This energy goes into our bodies, and animals’ bodies providing nutrients, and then the excrement recycled by nature back to the earth as fertilizer for the plants, and the cycle starts again.

Sunlight provides vitamin D for our skin and overall health.

Sunlight provides a mechanism for the convection cycle within the atmosphere creating weather patterns, rainfall, forested environments, and even deserts.  Solar energy aids in the evaporation of the ocean’s surface waters so that it condenses as clouds and falls as rain (in effect, as solar distilled water – PURE H2O) which we can then collect via rain gutters on our roofs, and place into collection vessels for watering our gardens, or for drinking water (the only way distilled (rain) water can be contaminated is via poisonous gases/pollution in the air, making acid rain).

The sun as a huge ball of fire in the heavens has the power of both life, and death, contained within it.  It can help the flower to bloom, or the carcass to decay.

To harness the sun’s energy in practical ways such as home heating, electrification, cooking, drying and preservation of food, etc., then we look to some basic principles at work in nature, and then take advantage of them.  After all, the sun’s energy is free to all, abundant, and only hindered by the occasional cloud or storm, which is actually also an effect of solar energy, and can be harnessed too!

There are three basic ways to use solar energy

ACTIVE solar
HYBRID solar systems


Passive solar systems harness the sun’s energy by just sitting there and doing their thing.  They are reliant on design, and have no moving parts, and generally no electricity is needed to make them work.

The water in a pond or puddle which warms up via the sun is utilizing, in nature, this passive effect.  During the day it absorbs the heat from the sun, and then at night it radiates it back to the night sky, cooling off.  The cycle repeats the next day, and the next, reliably, until the pond/puddle dries up (unless more water is added by rain, runoff, overflow, or by someone dumping more water into it – outside energy).

If the water is contained within a UV (ultraviolet) resistant container, such as a glass jug with a tight-fitting lid, then it will absorb and give off heat for just about forever, without evaporation ensuing.  If the water is colored black (BLACK ABSORBS and releases heat the quickest of any color, while WHITE REFLECTS it), or the outside of the jug painted black, then it will heat up faster, and cool down quicker as well.  People have used this simple principle to heat their homes, passively, in winter by placing such dark jugs of water, 55 gallon drums full of water, or even columns of water behind a piece of glass (or in a window) in or attached to their homes.

The reasons this works is due to the mass of the water, which is able to absorb and release the heat.  Countless variations of this simple idea can include other objects (besides water, although water is 4 times more effective than other types of mass) that have MASS such as concrete, rock, brick, adobe, etc.

There are different ways to promote this mass heat storage effect, some being trombe walls, rock storage heat units, solar window boxes, solar ponds, water walls, roof ponds, etc.  They key is that these types of mass work as a CONDUCTOR, rather than an INSULATOR.

Conductors conduct the heat through the mass, whereas insulators keep heat from progressing through the mass.

This is why we insulate the walls (keeping most of the mass in the floor, or interior walls, masonry stone fireplaces, etc.), and especially insulating the roof, of our homes… to keep the heat in during winter, and to keep the house cool in the summer, creating a more amiable, steady, and comfortable temperature inside the building/system. I also go into these principles in my blog article here on passive solar home design.

heating passively

Passive solar heating

The trick is to get the right amount of sunlight IN during the winter, and store it in an adequate amount of mass, to help heat the home, and to keep it all OUT during summer.  A passive solar house then, is one where the house itself becomes the solar system.

Please realize that if your house has any south windows (and almost every house does!) then you already have a passive solar house… it is just that some are designed more efficiently than others.

Windows/glass (glazing) on the south side (if you live in the northern hemisphere) of a solar house/system allows the heat in during the cold winter days, and then you pull the shades/insulated curtains/insulated shutters to close it up at night and hold the heat in.  It’s simple, and effective. Some people automate the shutters, but that brings us to the next section…


Active solar systems harness the sun’s energy by storing it and using some sort of moving part(s), or electrification to run. Where passive systems don’t have moving parts, ACTIVE solar definitely incorporate them.  That is the main difference.

A small solar panel on a safari hat that runs a fan to cool its wearer off is considered active solar.  A solar panel that charges a deep-cycle battery, which in turns supplies the power to run radios, equipment, TV’s, fans, motors, etc. are all examples of active solar applications.

Since active solar systems have moving parts, they are usually mechanical items which eventually break down and need fixed or replaced.  Due to this fact of life, active systems typically cost more to buy, maintain, fix, and use than passive systems.

Warning: If a new company sells an active solar items that they invented, and then the company goes out of business in a few years (about the time the mechanical parts start wearing out and need to be fixed or replaced) then the buyer may find himself/herself up a creek without a paddle on getting someone to fix it.  Make sure that any systems of this nature are bought from reliable companies with time-trusted products.


Hybrid solar systems are just that, a blend (hybridized system) between both passive and active systems.

Some people think of PV (photovoltaic) cells/panels as active systems, but in fact, the panels themselves only passively convert the sun’s energy into electricity.  The battery storage on up to the fans or motors which that energy operates is the active portion of the system.  The blending of the two is a hybrid system.

In essence, the “active” systems mentioned before could fall into the hybrid category, but there are many applications that are mostly passive, but incorporate a small fan, or tiny moving part (still mostly remaining passive except for these small “running” parts) and so they are called hybrid systems.

An example of a hybrid system would be a trombe wall (passive) which allows the sun’s energy to be stored in the wall, to be released at night.  If a small fan is used to move that heat around, helping the natural convection within the room, then it becomes a hybrid system.

If fans, and pumps, and forced-air furnaces and other “active” parts are employed then the system falls into the “active” section instead of just a hybrid label.

If you have a roof pond which is covered/uncovered during the day or night to either cool the house in summer, or help heat it in winter, then this is a passive system.  However, if you don’t want to mess with covering/uncovering the roof by pulling some ropes twice a day, and you decide to automate it, then it becomes a hybrid system.

Typically, I’ve found that hybrid systems tend to give us the most advantage in life compared to active systems, or passive systems, although there are surely some solar folks out there who would disagree with me.  For me, passive is best (no electricity needed whatsoever), but if a small amount if hybridization makes it more efficient then I say go for it!

A solar water distiller puts out approximately 0.1 gal/sq. ft. of sunlit glass/day.  A hybrid system, utilizing a small fan run on solar PV power stored in batteries, for instance, could increase the rate of distilled water on up to double or triple that (or more if designed right) in distillate output.

Solar system components

This next section covers batteries and solar photovoltaic (PV) systems, charge controllers, inverters and converters, and has some advice concerning these kinds of electrification systems.


There are two types of batteries typically used for solar systems.  Wet batteries, and so-called dry batteries.

WET BATTERIES: Lead acid/wet batteries require maintenance by topping up with distilled water.  These types are not used as much these days because of the inconvenience of topping up, the risk of corrosive spillages, and having to charge them in a ventilated area due to the hydrogen/gases which are given off due to charging, plus they are unsuitable for air travel.

DRY BATTERIES: Dry batteries are not really dry, but contain a gel so that they are considered maintenance free because their conducting chemicals are suspended in a gel-like substance so no topping up is required.  They do not last as long as wet batteries and are more expensive to replace, but this is the most commonly type of battery used in solar system applications.

NEVER use car batteries as they can explode.  The types of batteries I have heard solar enthusiasts recommend are the SEALED DEEP CYCLE marine batteries, although my friend Chuck Reel, says that he has never used the sealed type.

Deep cycle batteries are designed to be charged up, and run down (to 20%-25%), and then recharged (please use a charge controller), whereas car batteries are only designed to serve as a quick-start charge for vehicles.  Recommended is either a gel cell or AGM (Absorbed Glass Mat) type because they are more reliable.  These can be, and should be bought locally by the customer because they are HEAVY and expensive to ship.  Many (not all) solar PV suppliers/dealers do not sell batteries for this reason.


A potential customer calls in to a solar supplier asking for a solar system to run a 15 Watt blinking light atop a tower so airplanes won’t crash into it.  We will cover two possible locations — Texas, and Minnesota due to differences in peak sunlight hours.

West Texas has 6 – 6.5 peak hours of sunlight during the day so a blinking light (not being lit constantly because it blinks, and allowing for longer winter nights as compared to shorter summer nights, nighttime being when the light would be actually running, plus allowing for occasional cloudy days) would need a 50+ Watt solar panel (recommended is a US-64 Watt PV module for about $300+), a 100 amp hour gell cell or AGM sealed deep cycle battery (typically bought for approx. $100), and a 5 amp charge controller for $80+.

For the Minnesota location the peak hours of sunlight during the day is much less, perhaps 4 hrs, but we will say 3 hrs/day to make sure we don’t underestimate the energy needed, especially since Minnesota has many more cloudy days than west TX does (El Paso is called the “Sun City” with 360 days/yr of sunlight).  For this it is recommend to use an 80 Watt Sharp PV panel for $360+, the same 100 amp hour battery mentioned above, and the same 5 amp charge controller.


Charge controllers come in many sizes, but basically the charge controller is needed to ensure that the batteries you are charging will not be undercharged, or overcharged.  This can be a life saver regarding the life of the batteries, which are usually a hefty investment in any off-grid solar system (I personally prefer grid-tied net metering systems). A simple 5 amp charge controller for a single module system is around $80 (depending on where you purchase it).


What is the difference between an inverter and a converter?  Inverters and converters come in many forms, sizes, and prices, but before we go into that there are some basics we must know about AC and DC power.


The electricity in a typical home is AC (Alternating Current) and is 110 volt.  All typical home appliances, light bulbs, hair dryers, toasters, refrigerators (the highest electric-using appliance in the house!), etc., use AC power to run them.  220 volt power also runs heavier electric pulling appliances such as dryers, ranges, etc. and require heavier wiring and plugs but it is still AC.


The electricity generated by solar panels, and most often used by RV (Recreational Vehicles) is DC (Direct Current).  The appliances and lights in RV’s are all typically DC oriented and cannot be used in AC-wired homes just as AC oriented appliances and lights cannot be used in an RV (which is why people with RV’s must go to RV dealers for their repairs or to buy new appliances/lights).

This is also why solar panels are commonly found atop RV’s, because solar PV (photovoltaic) modules take the energy from the sun and convert it to DC energy which is then stored in deep cycle batteries (also oriented for DC power) for later use.  The power stored in the batteries supplies the energy to run lights and appliances, TV’s, radios, and so on at night when the sun is not shining.

It is possible to use DC powered appliances and lights by wiring them directly from the solar PV panels–without the need for batteries–but they can ONLY be used when the sun is shining if you are not willing, or ready, to purchase batteries.  If you do require batteries (which most people do who have solar systems) then you will need to convert that energy (unless you are an RVer) from DC into AC so the electricity can be used for typical AC-wired appliances and energy efficient (compact fluorescent) lighting.

INVERTERS convert DC power to AC power for use in homes equipped with standard AC appliances/lights.

CONVERTERS convert AC power to DC power for use with DC appliances/lights.

That is basically the difference between inverters and converters (they also come in sine wave, modified sine wave, and square wave types).  There are also DC/DC converters which help to run laptops or telephone equipment at 48 volts.

GRID-CONNECTED NET METERED HOMES: A complete solar system use inverters to take the battery-stored electricity (DC) and convert it to AC so standard appliances and lights can be used in the home.  This is the method most people go with to run their homes on solar power.  For folks wanting to sell back electricity to the electric company (grid-connected, grid-tied, or net metered homes) then one must have a special inverter (more expensive) that runs both directions–to and from the house–so that energy pulled from the grid (AC) can be used and monitored, as well as surplus solar energy you produce (DC) monitored and sold back to the electric company.  These types of inverters actually have built-in converters.


If you need to know how much electricity you now use, and what size of solar system you would need to run your house then contact any reputable solar energy supply company/business and ask for help.

Basically you will need to have, in hand, a COMPLETE LIST of all the appliances, TV’s, radios, lights (preferably energy-saving compact fluorescent or LED lights rather than energy-wasting incandescent (standard) bulbs), etc. and/or anything else you might occasionally run such as drills, hair dryers, etc.

Know how many watts they pull, and figure out the TOTAL load you’ll need, on average, and then work your way backwards to find out how many panels, batteries, etc. it will take to run your load.  Take into account if certain pumps or fans or equipment run more during winter/summer than at other times of the year.

If you live with standard A/C units (refrigerated air conditioning) instead of swamp coolers (evaporative coolers used mostly in arid climates) then you’d have to have a VERY expensive solar system, running into the tens of thousands of dollars just to run it since they are such huge energy wasters.

Also take note about your refrigerator as they are usually the largest electricity-pulling appliance in the house!  Make sure you have a very energy efficient (ENERGY STAR) fridge, or else just eliminate it altogether and buy a propane run fridge from any reputable company like or  The latter has a lot of other great products as well (used extensively by the Amish and conservative Mennonite communities).

If there are any electricity-using items (like hair dryers, electric can openers, microwaves, etc.) that you can live without, or replace with non-electric versions then do so!  Every watt saved, or used, counts!

I have a wattage chart and system to help the beginner figure out his/her electric loads, starting with your electric bill and working backwards, to figure out what size solar or wind system is needed, as well as tips and ways to reduce the load to begin with in order to save money up front.

how to solar energy projects

Book cover

You can utilize more of these tools in the solar PV section of my book, which is a free book download if you are a KindleUnlimited member.

I cannot yet afford to give the paperback version free, but soon I will have a solar photovoltaic system book that will be available as a free PDF download, so join our newsletter (right hand column near the top of this page) so you can be informed when it comes out!




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