Are you interested in generating power from solar, wind or another renewable energy source at your home or business? Learn more below.
The monthly electric bill for homeowners who install solar or wind may be lower because of the energy they receive from their system. But solar and other renewable generation systems can be a large investment, costing thousands – often tens of thousands – of dollars. So, while your electric bill may be lower each month, you won’t see a true return on your investment for years down the road. For example, if a Boise residential customer uses an average 952 kilowatt hours (kWh) a month and installs a 6-kW solar system, it could take 14 to 18 years to recover his or her initial investment in solar.
Additionally, there are different payment options for solar, including paying cash upfront or financing plans that include interest. Typically, any time a large purchase requires making monthly payments, interest charges are included. Adding interest increases the total cost and length of time to recoup an investment.
Idaho has some of the lowest electricity prices in the nation, largely due to our clean, low-cost hydroelectric system. In states where electricity is expensive, an investment in solar on-site generation can have a quicker payback. In California, for example, solar install prices are only slightly higher than Idaho’s, but their electric utility prices are significantly higher. Therefore, residents of California who choose to install solar can start saving money in less than 10 years. Idaho Power customers enjoy lower electricity prices, which usually means a much longer period to recover an investment in solar.
Comparing identical energy use for San Jose and Boise
|San Jose, California||Boise, Idaho|
|Average monthly electric use:||500 kWh||500 kWh|
|Average monthly bill:||$125||$45|
|System size to offset nearly 100% of use:||3.75 kW||3.75 kW|
|System net cost after tax credit:||$12,400||$8,400|
|Simple Savings1 Calculation|
|Estimated payback/break-even:||8 years||17 years|
|Total 20 year payback:||$21,500||$1,500|
|NET PRESENT VALUE1 CALCULATION|
|Estimated payback:||10 years||Beyond 20 years|
|Total 20 year payback:||$10,700||-$1,700|
Sources: Project Sunroof and PVWatts Calculator
1Find descriptions of simple savings and net present value under the question Why does Project Sunroof provide two different 20-year values? at idahopower.com/solar.
Another factor is electricity price changes. Prices fluctuate slightly year to year due to inflation, fuel costs, and other factors. In 2018, Idaho Power customers experienced a decrease in electricity costs. Looking forward, Idaho Power’s most recent Integrated Resource Planning (IRP) report estimates that relative fuel prices will increase, on average, 1.2% per year over the next 18 years.
Having power when the grid is down generally requires battery backup. Inverters are the part of a typical solar system that convert DC power to usable AC power. The vast majority of inverters are grid-connected and work only if the electrical grid is functioning normally. If the grid experiences an outage, the inverters sense the abnormality and will stop interacting with the grid. This helps keep work crews safe and the grid stable.
A small number of customers connect to the grid and have a battery backup. This allows them to use energy stored in the batteries while the power is out. Battery backup systems will add significant cost to the overall system.
The following graph shows a full day’s meter readings for a sample home with an on-site solar generation system connected to Idaho Power’s electric grid. One example is from August when the days are long and solar panels are at their peak generation. The other example is from January, when solar panels typically produce less than half the energy than they do in July and August because of the shorter days in winter.
The red line indicates zero kilowatt-hours. The yellow shading shows the times that the home’s solar is generating more energy than the home is using. During this time, excess energy is delivered to the grid. The blue shading shows when the home needs more energy than solar can provide, and the home is drawing energy from the grid.
*For simplicity, the chart shows a pure yellow color. However, the home may still rely on the grid even when solar is at its midday peak. For example, when a cloud goes by or a large appliance needs a boost, the grid is there to meet the home’s energy needs.
For a wind turbine, the space depends on the type and height of the system installed. A general rule of thumb is the turbine generator should be 20 feet above the top of anything within 300 feet of the system. Turbines should be erected away from structures to minimize the risk of falling on buildings during strong winds. The minimum distance between turbines and structures is typically equal to the combined height of the tower and blades, known as the “fall distance.”
The size of the system depends on many factors including the type of technology, the available space and how much energy your home or business uses. Your monthly electric bill shows your usage for the past 12 months and can be accessed through My Account, Idaho Power’s online account portal at idahopower.com/MyAccount. For customers interested in solar, visit idahopower.com/solar for calculators to help estimate system size and costs.
PVWatts Calculator is an online tool developed by the federal government for estimating solar generation based on location, geographic weather patterns and system design. This tool is available at pvwatts.nrel.gov. According to PVWatts, one kilowatt of south-facing rooftop solar in southern Idaho will produce between 1,348 and 1,458 kWh per year. The average home in Idaho Power’s service area uses 11,400 kWh per year, so it would need a minimum of 8 kilowatts of solar to match nearly 100% of its electricity use for the year.
To use PVWatts to determine the size system you would need, simply input your city, solar size in kilowatts (kW) and the calculator will estimate solar electricity generation by month and 12-month total. Compare the PVWatts estimate to your 12-month historical energy use, which you can find on My Account at idahopower.com/MyAccount. Tweak the kW in the calculator to find the size needed for your electricity use. If you decide to move forward with purchasing an on-site renewable generation system, a professional installer can help estimate a system’s monthly and annual solar generation. Be sure to compare the installer’s estimated solar generation with the information provided by PVWatts Calculator.
Do your research.
- Visit idahopower.com/solar to find:
- The Solar Checklist to navigate through your decision-making process
- A link to a solar calculator for a general idea of cost and payback based on today’s rates
- Tips for researching and choosing a professional installer
- Visit idahopower.com/customerGeneration to find:
- Rules for connecting on-site generation to Idaho Power’s electrical grid
- Information on billing and credits
- Applications and forms
- Register for My Account to view your past energy use and identify your energy needs
When you are ready to proceed, find an installer. Idaho Power recommends getting three bids and verifying the installer’s estimates with the information provided above.
You have options when it comes to renewable energy and using energy wisely. We have programs and tools to help you decide which Green Choices are best for you.
idahopower.com/greenChoices to see your renewable energy and conservation options
idahopower.com/solar for a starting point on your options and research
idahopower.com/CustomerGeneration for tariff information
idahopower.com/MyAccount Login to My Account for energy usage history
google.com/get/sunroof for an estimate on solar size, cost and payback
pvwatts.nrel.gov to estimate system size and energy output
oregon.gov/energy to find tax credits for Oregon residents
dsireusa.org a database of state incentives for renewables