What solar system size do I need?

After the government announcement about fantastic rebates in solar power installation, solar panels are so affordable right now. In fact, it is now possible to get a top-quality solar system to pay for itself within 3-5 years, saving your households tens of thousands of dollars over the life of the system. So what size solar installation system will best fit your home or business?

For an idea, a solar power system can save you up to $100 per kW in every quarterly bill, and you will get an output around 4 times its size as a daily average.

For example, a 10kW system will output around 40 kWh in a day & it can save you up to around $1000 in every quarterly electric bill. This rule of thumb for the households be good enough to search the answer to the question ‘What solar system size do I need?

To measure the accurate size of the solar system you need, you have collected a few pieces of key information from the household:

  1. What is the electrical load for the household? How much energy does the home consumed daily?
  2. What is solar resource/insolation? What is the strength of that sun or how much the Sun shines in your location?
  3. What is the portion of the home’s energy do you need from your solar power system? (i.e. 40%, 75%, 100%)

What is the electrical load for the household? How much energy does the home consumed on a daily?

The best way to calculate the above, you need to analyze the average of your last few months electric bills (to gather the average monthly electricity bill) and also need to find out the total consumption of kWh in a month for the household. After that, you need to calculate the average yearly usage with the above.

As per ‘Energy Information Administration’ it has estimated that the average family uses 940 kWh per month or 11,272 kWh/year.

There is another way to find out your home’s energy usage, it’s called TED (The Energy Detective), a whole-house monitor.

A whole-house monitor (TED) attached to your home’s electric meter and that will give you an accurate reading of energy consumed in the household on a daily basis. These types of equipment are really helpful because they will provide you with real-time information in a slick format.

What is solar resource/insolation? What is the strength of that sun or how much the Sun shines in your location?

The Solar intensity or Solar Insolation is measured in equivalent to the sun hours in a day at your locality. Full Sun hour is equivalent to one hour of maximum, or 100% sunshine received by any solar panel. You can take 6 hours of full sun hour, even though the sun may be above the horizon for 10-14 hours a day. One is a reflection because of the high angle of the sun in relationship to your solar panel. The second is additionally because of the high angle and also the quantity of the earth’s atmosphere the sunshine is passing through. When the sun is straight overhead the sunshine is passing through the least the smallest quantity amount of atmosphere.

Early or late within the day, the daylight is passing through far more of the atmosphere because of its position within the sky.

A tool called PV Watts, invented by The National Renewable Energy Laboratory (NREL) is used to give permit professional installers and non-experts to quickly obtain performance estimates for grid-connected PV systems.  The tool takes a few runs to get familiar with, but once you figure it will be critical for sizing your systems.

This is how you can determine the output of a system you are planning (A really simple but the rule of thumb formula):

(Ave. Hours of Sun) x (PV array wattage) x 75% = Daily watt-hours

We take the fudge factor as 75 percent; into account the real-world effects on a system.   It certainly can vary, but not more than 5-7%.

What is the portion of the home’s energy do you need from your solar power system? (i.e. 40%, 75%, 100%)

In a grid-tied system, you ought not to cowl 100% of the home’s electricity load, additionally you’ll not manufacture power once the grid is down.

Based on your solar resource, your household limitations, and your finance you’ll decide what share of the electrical load you would like to hide for your purchasers.

In choose states, you’ll sell excess electricity through a web metering program to your utility, however, it’s not out there altogether states.

Determine Insolation

  1. Locate a solar insolation table online to determine the insolation, the average number of hours per day that the sun produces peak sunlight (i.e. an accumulation of all sunlight equivalent to that amount of peak sunlight), for your area.
  2. Find the nearest city to you on the table and write down the average daily figure. To determine specific insolation data for individual days of the year.

Calculate the Energy Needs

  1. Plug the figure from Section 1, Step 3 “Daily kWh” into the following calculation. Use the average insolation value from Section 2, Step 2 for the “# hours” to determine how many kW you need your solar system to generate per day: Daily kWh / # hours = # kW
    e.g. 12 / 4 = 3
  2. Plug the answer from the previous step into the following calculation, which accounts for standard energy losses of solar PV systems: # kW x 1.3 (increase the size of the PV system by 30%) = # kW (actual size of PV system you need)
    e.g. 3 x 1.3 = 3.9In this example, you would need a 3.9 kW solar PV system to satisfy your home’s energy needs.

Total Number of Solar Panels

To calculate the size of your solar photovoltaic system, take your daily kWh energy requirement, and divide it by your peak sun-hours to get the kW output you need. Then divide the kW output by your panel’s efficiency to get the total number of solar panels for your system.

After you know the number of panels you need, the next step is to determine if you can fit them all on your roof and if you have the right kind of roof to mount panels on.

Selecting a Solar Panel System

  1. Measure how much space you have to mount your solar panels.
  2. Decide on a budget for your system.
  3. Find a system that satisfies your power requirements, but still fits within your space restrictions. This will determine if you need a roof-mounted or ground-mounted system and if you’re eligible for a solar roof shingle system.
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