How do I know how many PV panels I’ll need to “zero” out my Hawaiian Electric bill?

If you’re considering putting solar panels on your roof, one of the first questions you should ask yourself is how many panels you need to zero out your electric bill. Depending on where you live, the amount of sun you get, and your electricity usage, that number can vary quite a bit from person to person. So if you’re wondering what it takes to get started with solar in Hawaii, this guide will help you find out exactly how many panels are necessary to make your bill ZERO.

1) Figure out Your Energy Usage (kWh)

The first step to calculating how many solar panels you’ll need is figuring out your monthly energy usage. If you’re not familiar with all of your power-draining appliances, check them out and track their energy usage over time. The amount of energy that you use over time is usually measured in kilowatt-hours (kWh). For example, a 100W light bulb left on for 10 hours will consume 1 kWh of electricity.

You also have to find out the energy consumption used by all appliances like air conditioners, water heaters, refrigerators, kitchen appliances, TV/laptops, etc. It would be better if you could see an estimate of your energy bill from the past few months so that it would be easier for you.

2) How Much Energy is produced by Solar Panels in Hawaii?

Hawaii is the best place to install solar panels. The sun shines nearly year-round, and it’s one of the most expensive places to purchase electricity in America. However, how many solar panels do you need to produce enough energy to zero out your electric bill in Hawaii depends on the peak sun hours available per day for your home or business location.

In Hawaii Peak Sun Hours in summer are 6-7 hours per day, while winter peak sun hours are 5-6 hours per day. To zero out your electric bill, you need to be able to produce at least 1kW of energy per hour of peak sunlight.

3) Consider Electricity Rates in Hawaii

In order to make your Hawaiian bill ZERO, you need to generate more electricity than you use. You have to take into account the current cost of electricity by “Hawaiian Electric” and how much energy a solar panel produces per hour. In Hawaii, for residential consumers, the electricity rate is 37.92 cents/kWh.

4) Calculate Your System Size

First, you need to determine the system size best suitable to meet all your energy needs. There are two ways to do that, with an online power calculator or with a simplified method.

    kWh per month / (avg sunlight per day * 30) = kW solar system

So if a Hawaiian home uses 1000 kWh/month, an average of 5.5 hours of sunlight/day, the required system size will be 6.06 kW. Similarly, for 3 hours of sunlight daily, it will be 11.1 kW.

5) Find No. of Panels

Now, here’s where it gets a little tricky. The number of panels you need is based on your electricity usage and how much energy you want to generate. To find out how many panels you will need, divide the system size by panel watts.

For or 6kW system size and using a 300W panel rating, we get 20 panels in answer. Similarly, if you choose solar panels with a low rating of 200,250W then almost 30 panels will be required.

To make your Hawaiian bill ZERO, you have to consider a lot of factors including how much electricity you use per day /per month and what type of panels you choose as per generation capacity. The number of peak sun hours is also important in deciding how many panels you need to completely offset your electric bill.