How do I pick a Solar Company?

When picking a solar company that best fits a project’s needs, it’s important to make sure all the information is in hand. Reviewing websites, speaking with representatives, and knowing what questions to ask can ensure that information. It can be useful to ask about future maintenance support or schedules, any applicable warranties, cost breakdowns for the project, and the contractor’s experience installing systems in the area or of that type. Additionally, asking for further information about the specific system being installed can be beneficial. This can help in gathering information about expected system lifespans, troubleshooting for common issues, and routine maintenance needs or considerations.

Asking a wide range of questions and becoming well-informed on what a company offers can ease the energy transition and increase efficiency. It can also reduce any unwanted surprises, such as miscommunications about project goals, unexpected installation expenses, or lack of information from installers.

How do I know what type of Solar Panel to get?

There are various types of solar panels available on the market; however, many are still in various stages of development, or they can only be used in specific conditions. For the purpose of this article, the most common and accessible types are discussed, which are two specific types of silicon solar cells. Alternative cell types– such as thin-film, bifacial, or organic cells–were considered, but discarded as a focus due to the fact that solar companies in Puerto Rico usually do not offer them. These cells would be difficult to obtain in the mountainous communities, which is our primary focus. Silicon solar cells, which are mostly discussed here, primarily come in monocrystalline and polycrystalline forms. 

Monocrystalline silicon solar panels are cut from a single crystal of silicon and have black cells¹. They have high performance– able to reach efficiencies of over 20%–and have a higher capacity than polycrystalline cells². However, they can be more expensive to purchase and install than polycrystalline panels, with costs ranging roughly from $1-$1.50 per watt³. Manufacturing monocrystalline panels creates waste from leftover silicon, which can then be used to produce polycrystalline panels.

Polycrystalline silicon solar panels are composed of many silicon crystal fragments and have blue cells¹. They have slightly lower performance than monocrystalline panels, averaging around 15-17% efficiency². These panels are often lower-cost, ranging roughly from $0.75-$1 per watt³. Most solar companies tend to offer polycrystalline panels for residential buyers, so they can be more accessible.

When determining what kind of solar system is ideal for a project, it’s important to clarify the difference between the two types of panels and understand the benefits and drawbacks of each. Polycrystalline panels may be more common and less expensive for traditional projects, but monocrystalline panels may be more cost-effective and realistic in situations where there is a need for higher electricity output, such as having limited roof space. Knowing about each panel type and consulting with a chosen company can assist in determining what kind of system is right for the given situation.

What does this calculator tell me?*

This calculator gives a rough estimate of how much it would cost to buy small wind turbines to generate electricity. The calculator can make estimates for two types of wind turbines: one which supplies 3 kilowatts of electricity in power (the SD3 turbine) and one which supplies 6 kilowatts of electricity (the SD6 turbines). These two types of turbines are supplied by the Puerto Rico-based Golden Solar Technologies, who are the only wind turbine installers on the island (as of 28 November, 2023)¹⁰. Please note that this calculator may not accurately predict the cost of installment because pricing is very location dependent. Contact a wind turbine installer for more information. All estimates for power production are based on information from the SD Wind Energy website¹¹. Estimates are most accurate between approximately 8 and 16 mph yearly wind speed as this is the range of information provided by SD Energy. The turbines offered by Golden Solar are integrated with a generator and available as either grid tied or battery charge. They are also rated to survive up to a category five hurricane¹¹.

*Please note that all figures are estimates. Cost estimates are intended as a starting point for considering how much wind energy could cost. Variable wind speeds, installation costs, different energy consumption levels, and variability in energy production could make this calculation inaccurate for your needs.

How do I use this calculator?

1.) Determine the approximate average yearly wind speed in miles per hour of your municipality. 

1. Go to weatherspark.com¹²
2. Enter your municipality
3. Scroll down to find a yearly wind speed curve for your municipality, and estimate your average annual wind speed from that graph. Rough estimates in whole numbers are fine – an easy way to do this is taking the average of the highest and lowest average wind speed displayed.

2.) Determine your approximate yearly energy usage in kilowatt hours (kWh)

Add up monthly energy usage (kWh) values from your energy bills, or take a high usage month and multiply by 12 to get a maximum energy usage estimate.

3.) Enter data into the calculator

Note: This calculator was based on data in 2023 and may not be as accurate in the future.

How do I pick a turbine?

To properly estimate what hydroelectric system would best suit your needs, you will need an estimate of your water source’s DEPTH, WIDTH, and SPEED, as well as your required KILOWATT-HOUR usage. Luckily, you can measure the depth, width, and speed of your stream or river without a professional contractor and with relative ease. Make sure to measure depth and width in feet, and speed in feet per second.

1.) Measure Your Water Source’s Depth and Width

To find the average water depth of a stream:

1. Take a board long enough to lie across the entire width of the stream. 
2. Measure the length of the board to estimate the WIDTH.
3. Mark the board at one-foot intervals and measure stream depth at these points.
4. Sum all the depth measurements and divide by the total number of measurements taken to find the average DEPTH. 

2.) Estimate Water Source Speed

To estimate the speed of a stream:

1. Mark off a ten foot long section of a stream by placing a marker at the beginning and the end of the section. 
2. Place a floatable object a large distance upstream of the section. Once the object reaches the beginning marker, start a timer and end it once the object  reaches the end marker.
3. Do this multiple times in different sections of the stream
4. Find the average time by summing all these times and dividing by the total number of measurements taken.
5. Divide ten by this average time to get the average speed of the stream in feet per second.

3.) Find Your Monthly Kilowatt-Hour Usage

A kilowatt-hour is a metric of energy, or power consumed over a certain amount of time. You can find your kilowatt-hour consumption for a given month (kWh/month) on your electricity bill. It is recommended that you use an energy amount from a high-consumption month in order to ensure the calculator is accounting for your highest energy needs. 

Our Opinion

There are many different types of batteries that can be used for energy storage in a renewable energy system. We looked into these different types of batteries, and after ruling out other options we believe the best option for energy storage is lithium-ion batteries. We ruled out pumped hydro energy storage systems and compressed air energy storage systems because there are site requirements that need to be met to use them¹⁴. Flywheels and lead-acid batteries are slightly more on the expensive end¹⁴. Considering some other factors, sodium-sulfur batteries have relatively short lifespans in comparison to other batteries, and flow batteries have a relatively low power rating in comparison to other batteries¹⁴.

Although they are more expensive, lithium-ion batteries have many pros that we believe outweigh the higher cost. They have a longer lifespan than other batteries and can go through more charge-discharge cycles¹⁵. This means that lithium-ion batteries may be cheaper per charge-discharge cycle than other alternatives, although they are more expensive at face value. Lithium-ion batteries also do not require as much maintenance as other batteries¹⁵. Lithium-ion batteries are also highly efficient, and they are more energy dense (energy/weight) than other alternatives¹⁵.

How does the calculator work?

We wanted to make a calculator that can convert the estimated storage capacity required (of a battery) into a price estimation. Storage capacity is measured in kWh (kilowatt hour), with one kWh being an hour’s worth of 1000 watts. This led us to come up with the following formula.

The formula is split into two components: price of battery and shipping.

The battery price is determined by multiplying the average cost per kWh (found below) by the kWh needed. The shipping is determined by multiplying the average cost of shipping per kg of battery weight by the estimated weight per kWh needed (found below) and the kWh needed and then adding that number to the estimated baseline shipping cost (found below). The average price per kWh and average kg/kWh were found by calculating these values for 10 batteries found online and then finding their averages. This information can be found below in Table 1.