Solar Electricity on/off Grid NZ
Understanding Solar Electricity
Overview of solar power combining useful applications you can
do at home.
What is a PV cell or photovoltaic.?
How does selling your power back to the grid work?
Description of photovoltaic components working together.
How much does solar power cost and how do you connect to the grid?
Understanding solar energy is radiant energy.
When solar technology was originally developed the cost excluded most potential users except in places like space vehicles, photovoltaics are now used in everyday use this includes your house powering small items like a solar heating circulating pump or maybe a garden fountain light.
The first solar cell panels were installed on satellites powering complex computer electrical systems.
Everyday you use calculators powered from solar cells, usually located across the top front face of the calculator you will see shiny small square panels, these photovoltaic cells are the action center of the solar powered calculator never requiring batteries just a small amount of light.
Photovoltaic cells or modules packaged in one frame electrically connected modules become a group of solar cells or modules. Photovoltaics means - photo equals light ---- voltaic equals electricity, this involves the conversion of sunlight directly into electricity.
Increasing use of solar panels has become evident in many places, emergency call boxes, road signs or channel markers, sewer pump stations which send an electronic signal if a fault occurs, cars, boats, signs which illuminate school speed zones plus many other unseen applications.
How Do Photovoltaics PV Cells Work?
Understanding Solar Energy.
PV cells are made from materials called semiconductors, silicon is the major component of which is the most commonly used, this is changing as new discoveries of useful minerals in fools gold have been found to contain materials to extend PV cell life including significantly lowering the cost price.
Direct current is produced when light strikes the cell, a percentage of light is absorbed into
the semi-conductor material. This naturally occurring energy of the absorbed light is transferred to the high content of silicon semi conductor. The electrons become dislodged and loose, allowing them to flow freely for human use. Photovoltaic cells have one or more electric fields that react by forcing electrons freed by UV light absorption to flow in one certain direction only. This flow of electrons is DC or direct current, contacts are placed on the top and bottom of the PV cell, current is then drawn off for useful purposes. This downloaded current, combined with the PV cells voltage defines the wattage produced, this is a direct result of the cells electric field or fields if more than one.
We now have DC current which has to be converted into alternating current or AC to be compatible with the house electricity, to do this an inverter is used.
How do you connect your house to solar electrics?
How do we install our PV module, you will need some diy skills before you embark on any installation, you can not just place the solar cell anywhere, with simple guidance for orientation and solar sun angles you can achieve fantastic results.
Engage qualified electrical persons authorizing completion of any electrical work connected to the power grid.
Very few roofs have the perfect orientation although you will have a far higher success rate with solar power panels than with solar heating due to suggested distances from your solar collector and your solar ready cylinder.
The arc of the sun needs to be known first through summer and winter, southern hemisphere requires to be directly or within 20 degrees of north, north is best, minimum orientation angle aim should be the same as latitude at your project site, you have to consider winter sun direction and inclination to further your adjustments, recommended winter optimal angle is up to 10 degrees more, economic sense prevails for adjustments somewhere between latitude and plus 10 degrees, frames may be required for better angles and direction for maximizing solar energy gain.
Most PV systems are of the non tracking type in the Southern Hemisphere mainly because of the lower cost.
Auckland New Zealand has 36 degrees latitude so this is the minimum angle for this city.
Solar access needs to be considered, this means how much solar radiation penetration to your site can be achieved, trim back trees shading your property for optimal operation plus check building structures are not shading installed solar cells. Photovoltaic modules, if just one of the cells is shaded, solar power produced could be lowered to more than 50%.
Deciding what size solar cell system you need. this may be complicated by the fact weather being totally unpredictable plays a part in the amount of electricity produced not forgetting your household consumption will also vary.
Knowing your average household data usage, there are simple calculations your solar panel installer can use to determine just how many PV modules would suit your site. Consideration should be given for designs just under your average needs because you can't store excess electricity generated. System voltage is the next decision, which will be determined by the type of inverter used this will ultimately decide how many modules will be wired in series.
How To Size A Solar Array / Solar Cells
Calculating how many PV solar panels required will include reviewing your power account for Kilowatt usage history.
Estimating size of your solar array will also require knowing how many watt hours (Wh) you want produced in a single day plus the insolation level or value at your site.
Useful link for an in depth look at going off grid and the use of batteries.
Finding Watt-Hours Consumed By Appliances
What is a watt-hour? like amps, volts or current is a measure of energy.
Knowing your watt-hours remains the most crucial element of accurately establishing how large a solar system array to fix to any roof. If your vision is to connect your solar collector array directly to the grid off setting your costs you need to look at your electric power bill for the kilowatt-hours (abbreviated "kWh") on monthly basis, this knowledge will give the watts of solar panel generating capacity.
Your electricity consumption will change throughout the year due to changing seasons with this in mind you may wish to calculate your average monthly usage from the historical data found on most power company accounts.
You need to know the wattage of each electrical appliance or appliance load list this entails making up a detailed list to calculate appliance energy use.
If you are going to produce all your own electricity you will not need a connection to the national power grid, in this case you will be producing your own power supply which would include a battery bank, (battery bank efficiency for solar power batteries improves from 80% to 95% click on link LiFePO4 battery ) this move to off grid makes the kilowatt hours used even more important.
Formula For Estimating Energy Consumption In Dollars
Calculate - formula to estimate an appliances energy usage
(Wattage × Hours Used Per Day) ÷ 1000 = Daily Kilowatt-hour (kWh) consumption
1 kilowatt = 1,000 Watts
Multiply watts by the number of hours/days you use the appliance during the year for the annual power use, then divide answer by 1000 giving kwh consumption. You can then quickly work out the annual cost to run an appliance by multiplying the kWh per year by your local power companies rate per kWh consumed.
Fridges need careful attention due to being one of those silent consumers, to calculate the hours a fridge operates at maximum wattage, divide the hours the appliance is connected to the wall socket (turned on) by three.
Although "turned on" all the time, fridges cycle ON and OFF as required maintaining interior freezer or fridge temperatures.
Calculation examples of other appliances
210 Watts × 4 hours/day × 365 days or one year ÷ 1000 | ("1000") being1 kilowatt = 1,000 Watts
= 306 kWh × 17.5 cents/kilowatt
Personal PC Computer and LCD Monitor;
110 Watts + 140 Watts) × 4 hours/day × 365 days/year] ÷ 1000
= 365 kWh × 17.5 cents/kilowatt
Here is some sobering reading if your thinking of installing solar electricity. Solar panel price outlook for the next few years is expected to slide below 50c/w USD due to a 200% oversupply
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