Anyone help me to know what to consider when designing solar power for the home?

Question

Hello,

I know little on solar power for the home. I understand that it is possible to convert power to chemical form then use it as electricity. My question is, what elements are involved and how is the sizing being done?

I need the power design to power lights (say 10), TV and radio.

Answer 1

First of all, the conversion is chemical to electricity, as in the chemistry of a car battery which provides an output voltage.

To meet your needs, you need to figure how much useful sunlight you will have per day. Such sources as the Weather Channel, or National Climatology office can supply that to you. You need to determine the total load. Just add everything up, and that is the load you need to have sufficient energy to provide power for.  If this works out to be, let's say 200 watts, then you need at least a 200 watt solar panel, provided that you have enough sunlight from the time that you get up in the morning, until you go to bed at night. Count on it, you won't have enough sunlight for your needs, unless you live up in Alaska. Even then, there is part of the year where there will not be enough light at any time of the day. What you need, for full 24 hour coverage is a battery bank, and unless everything will run on 12 or 24 volts, then you need 1 or more inverters. With inverters, you lose 10% in conversion loss from DC to AC. Batteries should be RV, Trolling motor, or best yet, electric fork lift batteries, or the reasonable equivalent of such as these. I would recomment at least double to quadruple the total energy need for the solar panels, and to multiply the battery capacity by the total load supply that you have figured out, for at least a 24 hour run time. All of that, then multiplied by 90% to know how long the system will provide power, IF you use any DC to AC inverters. Within reason, the larger the battery bank, the better. Do NOT use regular car batteries, they will not last as long as you need them to last, unless you understand the difference between cranking amps, and reserve amps. Another point is that auto batteries are simply not designed for this kind of service.

Answer 2

Geography.  The farther south you live, the more economic sense solar power makes.  If you live in Seattle, you will have less power available that in you lived in Las Vegas.  In any event, you will need to focus on efficiency.

Put you lifhts on motion sensors so they automaticaly shut off when you leave the room.  This is also a good idea for a bathroom fan with a 5 minute delay, for air quality issues.

Replace the TV with a good book.

Solar is virtualy limitless in how long it will be available. It is very limited in how much power will be available.

Get eh power consumption of all you devices, measured in Watts, the look up how many Watts per square foot that photocells produce.  This will vary by geograpy of course.

Answer 3

Power Department

Application Notes:

Compact Portable

Solar Power Systems

This note is provided as a guide to those who want to power a variety of small electronics while outdoors & away from household power.

For the purposes of this note, we will assume that a DC power adaptor (ie vehicle adaptor) may or may not be available for all the devices you wish to power.

Spotlight...

SunLinq

The foldable, flexible solar panels for portable applications. Choose from 6Watt to 55W sizes. Perfect for the boat, RV, camping, or field research

Check it out...







Compact Portable Power : power anywhere





The compact portable power systems we create are essential to outdoor staff in the forestry, parks, & research communities. The goal in designing such systems is to balance reasonable equipment performance with lightweight, compact components that are easy to pack into remote areas on foot. If you need more power for more equipment, but still want to remain portable, read our note on larger portable systems.

A compact portable system is comprised of three components: Power source (ie. solar panel), power storage device (ie. battery), and power distribution (ie. AC inverter or DC outlets). We will consider each of these components in turn...

Power Source - Solar Panel Options

When it comes to lightweight, versatile panels, it doesn't get any better than the PowerFilm modules. These 5, 10 & 20W panels roll up into storage tubes for easy transport, and can be tied down to packs, tents, decks, or roofs. Accessories are available to connect to virtually any battery system. Other compact panels to consider include the SunLinq 6.5 Watt folding panel, SolarFlat 1.8 Watt, SolarPort 4.4 Watt.

Power Storage - Compact Battery Options

Batteries are often a big problem in portable power systems due to their size and weight. Why do you need a battery storage? Two reasons: first, if your equipment needs to operate from AC power, the inverter we supply will need to be able to draw more power than your solar panel can provide, not to mention that we have yet to meet an inverter that can draw power directly from a solar panel. Second, due to the ebb & flow of solar irradiation, it is necessary to have the panel charge a battery and draw power from the battery as needed. You can have the panel connected to the battery all day to capture all the sun's power, and then draw what power you need at any time of the day or night (the panel can remain connected at all times).

We provide a number of smaller batteries that provide enough power reserve to run a laptop without the aid of solar power from 20-90 minutes. The Outpost Power 4 battery stick is a compact, lightweight pack featuring a 12VDC plug, socket, and on/off switch - very handy for smaller systems. The Outpost Power 7 provides a maintenance-free battery with triple DC outlets and 75W detachable pocket AC inverter. At only 8lbs, it is one of the most practical portable power packs available. Still more portable than lugging a golf cart battery are the Outpost Power 12, and the Outpost Power 18 power packs. These last three kits include an AC inverter for household power anywhere along with battery status meter & input regulation that allows you to connect as much as 100W of solar power without worry.

Power Distribution - DC or AC Appliances?

Finally there is the issue of the gear you plan to provide power for. In many cases, manufacturers provide car adaptors as options for their equipment. Cell phones are a good example of this. These adaptors allow you to plug into any 12VDC power system that offers DC sockets like the one in your car, or into any of the battery systems mentioned above. Be sure to use these adaptors when you can - not only do they provide the correct power for the device, but they also eliminate the power losses associated with using AC inverters to obtain household power. Need more sockets? Add our 3-Way DC socket accessory to your system.

When car DC adaptors are not available, as is the case with many laptop computers & digital cameras, your only option is to use a small AC inverter to create household power from your 12VDC solar power system. These inverters are very simple to use - most smaller models up to 1000 watts come with a car adaptor as an option which allows you to plug directly into your system. We offer several models from the compact Smart AC 75Watt to the versatile 120 & larger 400 Watt sizes, and finally the powerful, yet still portable 700 & 1000 Watt models which come with hardwire options. Choose an inverter that provides at least 20% more power than you plan to consume (ie. a 75W inverter works well with a 50Watt laptop computer).

A few words about inverter technologies...

There are two types of inverter: modified sine wave and pure sine wave. Which type is for you depends on your budget and the type of equipment you plan to operate with it. The terms "modified sine" and "pure sine" refer to the smoothness of the AC waveform. A pure sine inverter most closely resembles normal household grid power, while a modified sine inverter simulates the waveform in a series of steps.

Should you care? Well, if you plan on running audio/video equipment, sensitive research equipment, or any other electronics which would be susceptible to "noise" from its power supply, then you need to consider a pure sine option such as our compact 150 Watt or 300 Watt models. If you plan to run equipment which has its own AC adaptor (like a notebook computer), or motors such as power tools or pumps, or lights, then the modified sine inverters will perform well for you and save you some money.



  

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Answer 4

There are so many things to consider.

First of all, chemicals have nothing to do with this, except that you may want a storage battery as part of the system.

This is going to cost you thousands of dollars.

You want about a 500 watt capability, from what you say. 10 CFL lights at 20W, 200w, medium sized TV, 200w, radio, 50w

Assumption 1: you will use this power only when available, ie, when the sun is shining brightly, for perhaps 6 hours a day in the summer, a lot less in the winter.

If this assumption is not valid, then you need large storage batteries, a much larger solar array, and lots of money.

Assumption 2: a small 50 amp-hr sealed lead acid battery. This will provide power for about an hour after the sun is down. You need a battery anyway to smooth out the irregularities in the output from the array.

point 3: electronics are a small charge controller and a 500 watt sine wave inverter.

point 4. You need a 500 watt array that will put out 14-16 volts in the sun. It will need to be mounted somewhere where it gets direct sunlight with no blocks.

put that all together, with a lot of time and money....

Pay back: 500 watts for 4 hours/day for 20 days/month is 500*80=40000 or 40kW-hrs, which you can buy from your power company for about $3 per month, depending on your rates.

So is a savings of $36 per year worth a $1000 investment?

This is why people tend to go with a larger unit, the payback is better. You can arrange it so that you sell power to the utility company when the sun is shining and you buy it from them when the sun is not shining.