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Heat naturally moves from warmer places to cooler places. Heat pumps use electricity to move heat in the opposite direction, from cooler places to warmer places, making the cool space cooler and the warm space warmer. Your refrigerator is a heat pump, moving heat from inside the refrigerated cabinet (cooler place) into your kitchen (warmer place). An air conditioner is a heat pump, moving heat from inside your home or business (cooler place) to the outside summer air (warmer place).
Heat pumps are also used to heat homes and businesses. A ground-source heat pump (GSHP) takes advantage of the fact that although many parts of the country experience seasonal temperature extremes -- from scorching heat in the summer to sub-zero cold in the winter—a few feet below the earth's surface the ground remains at a relatively constant temperature. Depending on latitude, ground temperatures range from 45°F to 75°F. Like a cave, this ground temperature is warmer than the air above it during the winter and cooler than the air in the summer.
GSHP systems consist of three parts: the ground heat exchanger, the heat pump unit, and the air or hot water delivery system (ductwork or piping). The ground heat exchanger is a system of tubes called a loop, which is buried in the ground near the building. A fluid (usually water or a mixture of water and antifreeze) circulates through the tubing to absorb or relinquish heat within the ground. GSHPs require underground trenches or wells to operate, and a property needs to have sufficient space and the right geological conditions to support them.
In the winter, the heat pump extracts heat from the heat exchanger and pumps it into the indoor air or hot water delivery system, moving heat from the ground to the building's interior. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger, effectively moving the heat from indoors into the ground. The heat removed from the indoor air during the summer can also be used to heat water, providing a free source of hot water for sinks, showers, clothes washers, etc.
Heat pumps require electricity to run, but can deliver more energy than they use.
There are approximately 50,000 GSHPs installed at homes and businesses in the United States each year. As of late 2017, CMLP was aware of 21 private homes heated and cooled with GSHPs in Concord.
These high-efficiency systems can provide 100% of a building’s heating and cooling needs. Though they require electricity to operate, efficient GSHPs can provide the same amount of heat using 65 to 80 percent less electricity than traditional baseboard electric heating – and reduce greenhouse gas emissions and operating costs accordingly.
Concordians also install ground source heat pumps because the systems reduce carbon emissions due to heating. This is a result of the combined high efficiency of the heat pump technology and the relatively lower carbon content of electricity, compared to other heating fuels.
Although the installation costs can be substantial, incentives and can reduce these costs, and in some cases, customers are cash flow positive from the day the system begins operation. This is more likely to be true when your investment in a GSHP is included in a mortgage. Due to their high efficiency, GSHPs offer excellent long-term energy savings as well.
For further savings, GHPs equipped with a device called a "desuperheater" can heat household water. In the summer cooling period, the heat that is taken from the house is used to heat the water for free. In the winter, water heating costs are reduced by about half.
GSHPs also improve humidity control by maintaining about 50% relative indoor humidity.
Ground-source heat pump systems allow for design flexibility and can be installed in both new and retrofit situations. Because the hardware requires less space than that needed by a conventional HVAC system, the equipment rooms can be greatly scaled down, freeing space for productive uses. GSHP systems also provide excellent "zone" space conditioning, allowing different parts of your home to be heated or cooled to different temperatures.
GSHP systems have relatively few moving parts and those parts are sheltered inside a building, so the systems are durable and highly reliable. The underground piping often carries warranties of 25 to 50 years, and the heat pumps often last 20 years or more. They usually have no outdoor compressors, so GSHPs are not susceptible to operational problems due to weather-related issues such as snow cover. In addition, the components in the living space are easily accessible, which increases the convenience factor and helps ensure that the upkeep is done on a timely basis.
Ground-source heat pumps come in several varieties:
Ground-source heat pumps can move heat to and from the ground or to and from water (water-source), if there is a pond or other water body nearby. Local regulations apply.
Most closed-loop ground-source heat pumps circulate an antifreeze solution through a closed loop -- usually made of plastic tubing -- that is buried in the ground or submerged in water.
The loops can be horizontal or vertical, depending on land area available, soil conditions and other variables. If the site has an adequate water body, this may be the lowest cost option. A supply line pipe is run underground from the building to the water and coiled into circles at least eight feet under the surface to prevent freezing. The coils should only be placed in a water source that meets minimum volume, depth, and quality criteria.
Open loop systems use well or surface body water as the heat exchange fluid that circulates directly through the GSHP system. Once it has circulated through the system, the water returns to the ground through the well, a recharge well, or surface discharge. This option is obviously practical only where there is an adequate supply of relatively clean water, and all local codes and regulations regarding groundwater discharge are met.
The best system, loop length and design for a particular building depend on a variety of factors such as climate, soil conditions, available land, required heating and cooling load, and local installation costs at the site.
The indoor components of a ground source heat pump move the heat to and from the ground and around the house. These ground-source heating and cooling units were installed in the basement of a new home.
The costs for GSHP projects in the 2 to 10 ton size range average $12,000 per heating ton, with 50% of projects ranging from $10,000 to $15,000 per heating ton, 20% above $15,000 per heating ton and 30% below $10,000 per heating ton, depending on the site and project type.
It is worth comparing the return on investing in ground source vs. air source heat pumps when considering heating options for your home or business. An air-source heat pump moves heat to and from the outdoor air rather than the ground. While air-source heat pumps are less efficient, they also cost less. For comparison, contractors are willing to install a one ton air-source heat pump unit (one outdoor unit + one wall- or ceiling-mounted unit) for $4,000 - $4,500, including electrical work. However, contractor prices can range from $3,000 to $7,000 for a single air-source heat pump, with an additional $350 - $800 for electrical work.
CMLP can put you in touch with Concord residents who have already installed ground-source heat pumps, and who would be happy to share information about their experience buying and using a ground-source heat pump. Contact Energy Specialist Pamela Cady at email@example.com or 978-318-3149 for referrals.
We suggest soliciting proposals from at least three ground-source heat pump installers. Before soliciting proposals, consider talking with Concord residents and organizations who have already installed ground-source heat pumps. CMLP’s Energy Specialist, Pamela Cady (firstname.lastname@example.org or 978-318-3149), can put you in touch with Concord residents who would be happy to share information about their experience buying and using a ground-source heat pump.
Consider asking the following questions:
Qualifications and Experience
Ground-source heat pumps installed at new or existing buildings are eligible for rebates, though the system must be used for heating (in addition to heating use, systems may providing cooling as well). Projects with a single heat pump serving multiple units in a multifamily residential or multi-unit commercial building can apply jointly with one application, subject to existing caps. A single apartment or condominium can also apply individually. Projects must have rated heating capacity no greater than 10 tons (120 kBTU/hr).
Annual Rebate Caps
For each 12 month period, each residence is eligible for a maximum rebate of $3,125 per project site address at the base rebate level, $4,000 with the 120% Income-Based Rebate, or $7,500 with the 80% Income-Based Rebate. Customers may apply for more than one GSHP rebate over the life of the GSHP rebate program. However, a customer may receive only one GSHP rebate within a twelve month period. This policy is subject to change without notice. Note that these CMLP rebates have *no expiration date*.
Project installation may not commence until after the application has been approved by CMLP and the system owner has received an award letter. Projects that have already commenced construction are not eligible for the rebate.
Energy Assessment Requirement
All existing buildings must have an energy efficiency assessment completed within the past four years or have an energy assessment scheduled to occur and completed within six months of project completion. CMLP highly recommends that priority recommendations from the assessment be implemented before or in coordination with the installation of the GSHP. Making a building more energy efficient can reduce the size and cost of the GSHP needed to heat and cool your building.
Households heating with natural gas can contact MassSAVE at (866) 527-SAVE (7283) or www.masssave.com/en/saving/energy-assessments/ for an assessment. Businesses heating with natural gas can find information about Mass Save facility assessment at https://www.masssave.com/en/saving/business-rebates/facility-assessments/
All others can sign up with Energy New England at email@example.com, (888) 772-4242, or https://ee.ene.org/. Energy New England, CMLP’s energy assessment provider, provides no-cost home energy assessments, and business energy assessments at a 50% discount. CMLP covers 50% of the cost of a full-scale business energy assessment.
New buildings do not require energy assessments, although energy assessments are still recommended.
Rebate Type Eligibility
Rebate levels for GSHP systems are calculated per heating ton (12,000 BTU/hr). Residential rebates are limited to the first five tons of heating capacity per housing unit. Non-residential entities can receive funding for up to ten tons of heating capacity through this program. Income-based rebates are available for qualifying residential applicants.
If the project meets the above eligibility requirements, system owners should next determine which rebate type they are eligible for based on the following table:
Income-Based Thresholds by Household Size
$625 per 12,000 BTU/hr**
(up to a maximum rebate of $6,250)
Annual Gross Income
(up to a maximum rebate of $3,125)
$800 per 12,000 BTU/hr**
(up to a maximum rebate of $4,000)
$1,500 per 12,000 BTU/hr**
(up to a maximum rebate of $7,500)
*To receive an income-based rebate, the customer must complete one of the accepted income verification methods. Please see the “How Do I Qualify for an Income-Based Rebate?” question below for more information about income-based rebates and income verification.
**For the purposes of determining rebate levels for GSHPs, CMLP uses the American Heating and Refrigeration Institute’s (AHRI’s) heating capacity for the system.
All applications must be submitted and approved by CMLP prior to starting project construction, and, to be eligible for a rebate, construction must not commence until an award letter is issued. Once the system owner has decided to move forward with the project, the installer should apply for a rebate on the system owner’s behalf.
First, select a GSHP installer, who will submit the rebate application on your behalf.
The following resources can help you identify potential installers:
In order for your GHSP installation to be eligible for a CMLP rebate, the following conditions must be met:
Your installer must submit a copy of the certificate for one of the accreditations listed above with the rebate application.
If not currently holding one of these credentials, your installer must provide references for three GSHP installations, including phone numbers and email addresses for each reference. Rebate approval is contingent upon a successful reference check. Installers must achieve one of the above credentials within one year of submitting their first GSHP rebate application to CMLP in order to be eligible to submit further GSHP rebate applications to CMLP.
2. Your installer must agree to fix any system defects or significant workmanship issues identified during the first year after the project completion date.
CMLP recommends that our customers:
In order to be eligible for a rebate, projects must meet the following requirements:
A. Equipment Requirements
a. In the application, EER and COP must be calculated using the following equations:
i. EER = (full load EER + part load EER) / 2
ii. COP = (full load COP + part load COP) / 2
b. EER and COP figures for the above calculations must use the AHRI rated ground loop heat pump (GLHP) figures for closed-loop systems and the AHRI rated ground water heat pump (GWHP) figures for open-loop systems.
3. GSHP systems must be designed with full-load heating capacity between 90% and 120% of peak heating load (BTU/hr for heating) according to the applicable heat load calculation. On a case-by-case basis, CMLP will consider eligibility of GSHPs installed at buildings with heating capacity sized below 90% of peak heating load if designed to operate in conjunction with back-up or peaking heating systems.
4. All GSHP systems must be installed by licensed contractors and/or plumbers in accordance with the National Electric Code and manufacturer’s specifications and must conform to all applicable municipal, state, and federal codes, standards, regulations, and certifications, as well as program requirements. At a minimum, a contractor must possess an EPA 608 license to handle refrigerant and an electrician license to complete the electrical work on the heat pump.
5. Blower motors must be multi-speed or variable-speed, high-efficiency motors. Motors qualify as “energy-efficient” if they meet or exceed the efficiency levels listed in the National Electric Manufacturers Association’s (“NEMA’s”) MG1-1993 publication. Single-stage water-to-water console units with a capacity less than 2 heating tons are eligible to be preapproved by CMLP, provided these types of units satisfy all of the other eligibility requirements described herein.
6. Systems must meet ANSI/AHRI/ASHRAE/ISO Standard 13256-1 for water-to-air models, Standard 13256-2 for water-to-water models, or AHRI Standard 870 for DX models.
7. All compressors must use two-stage, multi-speed, or variable-speed drives, unless they are water-to-water units. Single-stage water-to-water systems are allowed, provided they include accumulator tanks with the greater of ten gallons of capacity per heating ton or industry/manufacturer recommended best practice.
8. All GSHP systems receiving a rebate from CMLP must be covered by a minimum five-year manufacturer’s warranty.
9. CMLP may submit open-loop, horizontal-loop, and direct exchange system designs to a third-party consultant to evaluate a project’s design and reserves the right to submit designs of other system types for review. Installers should be prepared to work with the reviewer to answer any outstanding questions about the project’s design and must respond within seven days to any information requests.
B. Well Requirements
10. Vertically bored closed-loop projects must have a minimum depth of 150 feet per 12,000 BTU/hr of heating load served by the system (i.e., the lesser of capacity and peak load). Capacity must be determined using the method used to calculate rebate values (see Section A. 2. a under Step 2). This must be sufficient to maintain a minimum entering water temperature of at least 30°F, with a recommended best practice of at least 32°F. Direct Exchange (DX) systems require a minimum of 120 feet of borehole depth per heating ton.
11. Closed-loop bore grouting must have a grout conductivity equal to or greater than anticipated earth conductivity of the drill site up to 1 BTU/hr-ft-°F.
12. There must be at least 15 feet of separation between closed-loop bore holes.
13. All projects must comply with the MassDEP Bureau of Resource Protection Drinking Water Program, Guidelines For Ground Source Heat Pump Wells, and Underground Injection Control Program (December 2013, which may be amended from time to time) found at www.mass.gov/eea/docs/dep/water/laws/a-thru-h/gshpguid.pdf
C. Open Loop Requirements
14. All open-loop GSHP wells shall be installed in conformance with MassDEP’s Private Well Guidelines (www.mass.gov/eea/docs/dep/water/laws/i-thru-z/prwellgd.pdf) (as amended) or MassDEP’s Guidelines and Policies for Public Water Systems (www.mass.gov/eea/docs/dep/water/laws/a-thru-h/glintro.pdf) (as amended), whichever is applicable. All GSHP wells shall be installed in conformance with 313 CMR 3.00: Certification of Well Drillers and Filing of Well Completion Reports (www.mass.gov/eea/docs/dep/service/regulations/310cmr46.pdf)
a. Open loop systems must register for a permit with the Massachusetts Department of Environmental Protection (“MassDEP”)’s Underwater Injection Control (UIC) program. The UIC registration number must be noted on the Project Completion Form at the time of project completion. Open loop systems installed on parcels of land used for single-unit residences are exempt. (https://www.mass.gov/underground-injection-control-uic)
15. A standing column well must include a bleed circuit and drywell to maximize thermal efficiency based on available water production
16. Applications for open- and horizontal-loop systems must explain the method for determining pressure and flow rate.
D. Horizontal-Loop Project Requirements
17. The Application must include the file from the horizontal-loop design software showing inputs and system design specifications.
E. Direct Exchange System Requirements
18. Direct exchange (DX) heat pumps, which circulate a refrigerant through a closed-loop copper pipe system (whereas most systems utilize plastic pipes that circulate water or a water antifreeze mixture), must meet the following additional conditions:
a. DX wells require cathodic protection ensuring a minimum expected well life of 20 years.
b. DX System Owners must certify that they will undergo an end-of-life decommissioning that includes full refrigerant recovery.
c. Each DX system must undergo a design review through CMLP’s third-party consultant.
d. The refrigerant must be R-410A. If the installer intends to use a different refrigerant type, CMLP will consider it when then application is submitted.
e. The entire well depth interval for DX wells shall be grouted with thermally enhanced grout that achieves hydraulic conductivity of 10-7 centimeters per second or less (per MassDEP).
f. A permanent placard must be attached to the heat pump unit, detailing:
i. Loop field refrigerant content, type, and volume;
ii. Loop locations description;
iii. Loop piping material;
iv. Required maintenance schedule on loop field, refrigerant, and heat pump; and
v. Planned decommissioning date and process, consistent with loop field useful life.
g. The installer must provide a detailed operational handbook for the System Owner that provides an overview of system design, operations, and the information stated in 18.b. above.
F. Heat Load Calculation Requirements
19. Equipment must be sized with a building peak heating capacity (BTU/hr) calculated using the Air Conditioning Contractors of America (“ACCA”) Manual J (for residential) or Manual N (for commercial) building heat load calculation method.
20. Installers must submit the summary page of the applicable heat load calculation of the building’s peak heat load at the 99% dry bulb heating design temperature for the most relevant ACCA location. Heating set temperatures may be between 68 and 72 degrees Fahrenheit.
21. CMLP strongly recommends all projects incorporate system performance monitoring technology to help owners understand performance throughout the year.
CMLP may choose to monitor a subset of systems installed under this program. To be eligible for a rebate under this program, the system owner must agree to allow metering and monitoring to be conducted on their project for up to twenty-four (24) months after installation, if requested. The system owner will be required to submit fossil fuel bills for two (2) years prior to installation (for existing buildings) and for the duration of the performance monitoring. Monitoring equipment would be paid for and installed directly by contractors to CMLP with no direct cost to the system owner. Data would be collected and analyzed for program evaluation purposes and will not impact the rebate received by the system owner.
H. Deviation from Requirements
Although CMLP typically does not allow deviation from these design requirements, certain site characteristics may lend themselves to alternate system designs. If for technical reasons, a design requirement cannot be met for an installation, the installer may request a waiver. All variations must be explained in detail in the Project Notes field at the bottom of the application, and output from geothermal modeling software must be submitted. CMLP may send these applications to CMLP’s third party consultant for review and consideration.
I. Other Project Requirements
Installed systems must meet all applicable state and local laws and ordinances, including applying for and receiving a building permit and, upon project completion, receiving sign-off from a local building authority.
Step 3: Apply for a Rebate
Prior to deciding to move forward with a system, residents should determine if they are eligible for the Income-Based Rebate, as described under the “Who’s Eligible for a Rebate?” question above. For example, a household of four with annual income of $132,230 or less may qualify. If eligible, complete one of the three income verification methods described in the “How do I qualify for an Income Based Rebate?” question below.
Once the system owner has decided to move forward with the project, the installer should complete and submit the application on the system owner’s behalf, with the assistance and approval of the system owner. Application documents must be emailed to firstname.lastname@example.org. To expedite the review, please include “GSHP Application: [Project Site Name]” in the subject line. Both the installer and system owner should review all information before submitting it to CMLP.
All applications must be submitted and approved by CMLP prior to starting project construction, and, to be eligible for a rebate, construction may not commence until an award letter is received.
All complete applications must include:
1. Application Form: A completed Excel Application Form
a. Energy Assessment: Date of completed or scheduled energy assessment must be noted on rebate application. Assessments performed through CMLP’s energy assessment program, Concord’s Green Your Heat Program, the MassSave program or other energy assessment providers are all accepted.
i. If you believe you had an assessment in the last four years through CMLP, but do not know the date, contact Energy New England, CMLP’s assessment provider, at 1-888-772-4242 or email@example.com for assistance.
ii. If you believe you had an assessment in 2015 or 2016 through Concord’s Green Your Heat Program, but do not know the date, contact CMLP’s Energy Specialist Pamela Cady at firstname.lastname@example.org or 978-318-3149 for assistance.
iii. For the date of a MassSave assessment, call 800-632-8300.
iv. To schedule an energy assessment, contact Energy New England, CMLP’s assessment provider, at 1-888-772-4242, email@example.com, or https://ee.ene.org/.
2. Contract: Installation contract signed by both the system owner and the installer
3. Electric Bill: A copy of a recent electric bill from the project site. New construction projects can submit the electric bill or a request for electric service at project completion.
4. Heat Load Calculation: The summary report from the Manual N (commercial) or Manual J (residential) calculation of the building heat load, as described in Section F under Step 2: Select Eligible Equipment.
5. AHRI Rating Certificate: A copy of the Air-Conditioning, Heating, and Refrigeration Institute (“AHRI”) rating certificate for each heat pump model installed.
Certain projects must also submit additional documents, as follows:
1. Income Verification: Residential Income-Based Rebate eligibility verification (if applicable). Eligibility thresholds and income verification methods can be found under the “How do I qualify for an income-based rebate?” question below.
2. Tax Documentation (if applicable) –
3. Design Reports: Horizontal-loops systems (if applicable) – Software design report showing all system inputs.
4. Flow Rate: Open-loop systems (if applicable) – Detailed estimation of well water flow rate.
5. Modeling Summary: Non-residential systems (if applicable) – Modeling software summary page.
Rebates can be paid to the system owner or to the installer, provided that the system owner provides written permission in the application. If the application meets all requirements of this program and funding remains available, CMLP will issue the rebate payment to the payee via mail.
The rebate may be combined with any other local, state or federal incentives, and applicants are encouraged to do so where possible. CMLP will not provide funding that would, in CMLP’s sole determination, exceed total project costs. Total project costs shall include all costs presented in the application, less all other available incentives, including any state or federal rebates, subsidies, and tax incentives, discounted to present value where necessary. CMLP will evaluate these situations on a case-by-case basis, and reserves the right to reduce any award projected to exceed total project costs by an amount sufficient to prevent the excess.
The Town of Concord assumes no liability for any equipment, installation or damages, and may inspect equipment to verify the above information at any time up to 1 year after receiving the rebate application.
Step 4: Receive Rebate Award Letter
Upon receiving the application, CMLP staff will send two separate emails. The first email will confirm that the application has been received; the second email will indicate one of the following statuses:
Applications will be evaluated to ensure that the project will meet the eligibility and project requirements described above. CMLP reserves the right to accept, assign design reviews, or reject applications based on completeness, qualitative criteria, and available funding; to make no awards; to award less than the applicant requests; and/or to award less than the maximum amount of funds potentially available through this program. If CMLP elects to conduct a design review, the installer must be prepared to answer the reviewer’s questions about the project’s design and must respond within seven days to any information requests.
CMLP will notify applicants of their application status within four weeks of receipt of a complete application, barring extenuating circumstances. If the application meets all requirements of this program and funding remains available, CMLP will issue an award letter to the system owner and installer via email that will provide details on the award amount and, among other pertinent information, state which party will receive payment (the “payee”). CMLP will also attach a Project Completion Form, which will be submitted to CMLP upon project completion.
Step 5: Complete Project:
Project installation may commence only after receipt of the award letter. Projects must be completed within six months of the award date on the award letter for projects at existing buildings and within twelve months for projects at new construction buildings.
Upon project completion, the installer in cooperation with the system owner will complete and submit supporting documentation to CMLP, including:
1. Project Completion Form; and
2. Completed GSHP manufacturer or distributor start-up sheet. This documentation should be submitted by email to firstname.lastname@example.org with “GSHP Project Completion: [System Owner Name (residential) /Site Name (non-residential)]” in the subject line.
Step 6: Receive Rebate Payment:
Rebates can be paid to the system owner or installer, provided that the system owner provides permission in the application. Upon approval of the project completion documentation, payment will be issued to the designated payee within 4 weeks, barring extenuating circumstances.
In the interest of increasing access to ground-source heat pumps to all residents of Concord, CMLP offers additional incentives for households with income below 80% or 120% of the state median income. Eligibility thresholds are determined based on household size. Eligibility for the income-based rebate is based on the income of the system owner’s household.
Eligibility is based on total household income (Tax Return Form 1040 line 22), as determined by the system owner and household members’ federal income tax filings for the most recent year available. Each system owner household is only eligible to receive the income-based rebate at one residence.
Income-Based Rebate Adder Thresholds by Household Size
80% of State Median Income
120% of State Median Income
To receive the Income-Based Rebate, the system owner must complete one of the following three income verification methods:
CMLP offers the R-7 “Electric Resistance & Heat Pump Heating Systems/DHW” rate for heat pump users, a special winter rate designed to prevent an unintended spike in electricity charges for electric heating customers as a result of CMLP’s tiered rate structure. This rate may benefit you if you already use more than 600 kilowatt-hours in some winter months, or if you expect to do so once your heat pump is installed.
However, In order to take advantage of this rate, you must request that a separate meter be installed by CMLP. This meter will record the electric usage of your heat pump. Electricity use recorded on this meter from October 1st through May 1st will be subtracted from the normal billing meter and billed at $0.14431 per kWh. From May 2nd through September 30th, the use through this meter will be billed under the regular R-1 Rate, which ranges from the tier 1 rate of $0.14431 to the tier 3 rate of $0.18685 per kWh, depending on how much electricity your household has used that month. CMLP’s R-1 rate schedule describes how your electric rate changes depending on how much electricity your household uses in a given month.
CMLP will supply and install the separate meter at no cost to you. However, you will need to pay an electrician to install a meter socket for the new meter. An additional electrical panel is typically needed as well. Costs for a meter socket/electrical panel can range from $1,000 to $4,000. The time it will take you to recoup the cost of the new meter socket/panel through electricity cost savings depends on several factors:
Please note also that customers who have a solar array usually expect that solar electricity will lower the portion of their electric bill attributable to the electricity needed to power their heat pump during the winter. However, if a heat pump is separately metered so that a customer can receive the Electric Resistance & Heat Pump Heating Systems/DHW rate for winter usage, CMLP is unable to offset the winter usage measured by the separate meter with solar electricity generated by the array. Therefore, having a solar array will not lower a customer's winter bill for heat pump electricity usage if the Resistance & Heat Pump Heating Systems/DHW rate is in effect. During the summer, when the Resistance & Heat Pump Heating Systems/DHW rate does not apply, solar electricity will offset the portion of an electricity bill due to a heat pump being used for air conditioning, even if the heat pump is separately metered.
Further, heat pump customers with solar would need to locate the second meter next to the existing house meter in order for the solar electricity powering the heat pump to be accounted for properly. This can require longer wire runs that increase the cost of the meter socket installation.
Please consider these factors when deciding whether to invest in a separate meter/electric panel.
If you have further questions about the Electric Resistance & Heat Pump Heating Systems/DHW rate, please contact Carole Hilton, Customer Service Coordinator, at (978) 318-3158 or Chilton@concordma.gov.
Contact Pamela Cady, CMLP’s Energy Specialist, at email@example.com or 978-318-3149.