Cooperation Agreement AC cabling system for solar micro-inverter between Phoenix Contact GmbH & Co. KG Flachsmarktstraße 8 32825 Blomberg Germany as well as Phoenix Contact USA, Inc. 586 Fulling Mill Road Middletown, PA 17057 HARRISBUG, PA. 17111-0100 USA -hereinafter Phoenix Contact - and EnphaseEnergy Inc. 201 1st Street Suite 11 Petaluma, CA 94952 USA -hereinafter ENPHASE- - hereinafter singly or jointly referred to as CONTRACTUAL PARTIES- on thedevelopment of an AC cabling system for solar micro-inverter as well as the tools needed for the manufacture of products andthe supply of the developed products

Exhibit 10.16

CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS AMENDED. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO THE OMITTED PORTIONS.

Cooperation Agreement

“AC cabling system for solar micro-inverter”

between

Phoenix Contact GmbH & Co. KG

Flachsmarktstraße 8

32825 Blomberg

Germany

as well as

Phoenix Contact USA, Inc.

586 Fulling Mill Road

Middletown, PA 17057

HARRISBUG, PA. 17111-0100

USA

-hereinafter “Phoenix Contact” -

and

Enphase Energy Inc.

201 1st Street Suite 11

Petaluma, CA 94952 USA

-hereinafter “ENPHASE”-

- hereinafter singly or jointly referred to as “CONTRACTUAL PARTIES”-

on

the development of an AC cabling system for solar micro-inverter

as well as the tools needed for the manufacture of products and the supply of the developed

products

2

Article 1 - Preamble

Phoenix Contact is a company with worldwide operations in the field of electrical connection technology, automation, surge voltage protection and electronic interface systems. ENPHASE is a company specializing in design, manufacturing, and distribution of solar micro-inverter and associated products.

The CONTRACTUAL PARTIES agree to work together to develop and produce unique connectors and cable assemblies to create an AC cabling system for use by ENPHASE for its solar micro-inverter products. In addition the CONTRACTUAL PARTIES agree that ENPHASE shall be generally free to appoint any third parties as supplier for AC cabling systems for use in solar micro-inverter products in terms of a second source supply chain.

Article 2 - Definitions

3

Article 3 - Cooperation between the CONTRACTUAL PARTIES

Should any deviations from the time schedule and/or the roadmap become apparent, Phoenix Contact shall notify ENPHASE promptly by Email or other written communication.

The development work to be performed on the SUBJECT MATTER OF THE AGREEMENT may be assigned to third parties by Phoenix Contact. Phoenix Contact shall bind the third parties to secrecy to an extent that corresponds to the requirements of Article 7. Phoenix Contact shall remain fully responsible to ENPHASE under the terms set forth in this Agreement. Phoenix Contact shall be fully responsible to ENPHASE for any acts of such third parties in violation of the terms of this Agreement.

This product design information according to sentence 1 of 3.3 shall specifically include:

[***] = CERTAIN INFORMATION ON THIS PAGE HAS BEEN OMITTED AND FILED SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO THE OMITTED PORTIONS.

4

Phoenix Contact shall undertake to explain the RESULT verbally – upon request of ENPHASE also once at ENPHASE site.

When creating the SUBJECT MATTER OF THE AGREEMENT, Phoenix Contact shall apply state of the art science and technology. ENPHASE shall not be entitled to issue instructions to the employees of Phoenix Contact.

5

If the contact person of either CONTRACTUAL PARTY changes, it shall inform the other CONTRACTUAL PARTY in writing.

All queries, reports, etc. shall be directed by one CONTRACTUAL PARTY to the other through the respective contact persons.

Article 4 - Development costs

For performing the development work on the SUBJECT MATTER OF THE AGREEMENT, Phoenix Contact shall pay for all design, tooling and production equipment expenses, except as such expenses may be recovered by Phoenix Contact through the remuneration provision in section 8.3.

Article 5 - Changes

6

Article 6 - Rights to RESULT

Phoenix Contact may not make the design connector interface according to Annex 8 available to any customer other than ENPHASE.

For this aforementioned non-protectable inventions or ideas (design connector interface in combination with the latching mechanism according to Annex 8 and the trunk and drop wiring design according to Annex 8) ENPHASE shall have all ownership rights, including the right to any worldwide use and exploitation. If this is embodied in drawings, models, reports, data carriers, samples and any other objects, these shall pass into the sole and unlimited ownership of ENPHASE upon their creation, namely in the respective processing state.

7

8

Article 7 - Tools

Article 8 - Delivery/Purchase quantities, Pricing and Delivery Schedule

9

[***] (US $[***]) for [***] to [***] pieces (connector and splice box) per part.

[***] (US $[***]) for [***] to [***] pieces (connector and splice box) per part.

ENPHASE shall inform Phoenix Contact promptly of its intent to cease purchasing under this Agreement. In such case, ENPHASE shall additionally purchase finished or semi finished CONTRACTUAL PRODUCTS and raw material to use up any raw material purchased for ENPHASE CONTRACTUAL PRODUCTS. This shall not exceed three (3) months of forecasted quantities, if not otherwise agreed between the CONTRACTUAL PARTIES.

Article 9 - Secrecy

The non-disclosure agreement (Annex 5) between the CONTRACTUAL PARTIES effective as of 16 April 2010 is an integral part of this Agreement. Notwithstanding the term set forth in the non-disclosure agreement, the CONTRACTUAL PARTIES agree that it shall remain valid until the end of five (5) years after termination or expiration of this Agreement. Secrecy obligation will be applicable in particular to INFORMATION and product design information.

[***] = CERTAIN INFORMATION ON THIS PAGE HAS BEEN OMITTED AND FILED SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO THE OMITTED PORTIONS.

10

Article 10 - Promotion

With the prior written approval of ENPHASE, Phoenix Contact shall be entitled to advertise the CONTRACTUAL PRODUCT as customer-specific product in all areas after the series release (flyer, press release, catalogs, brochures, exhibition panels, etc.) as well as exhibit the CONTRACTUAL PRODUCT at trade fairs, amongst others. In addition, with the prior written approval of ENPHASE, Phoenix Contact shall be entitled to promote this cooperation.

Article 11 - Quality defects

first, demand another remedy of defects or re-delivery from Phoenix Contact at its discretion and only after a renewed unsuccessful remedy of defects or re-delivery

Any further or other claims or rights of ENPHASE due to quality defects do not exist.

[***] = CERTAIN INFORMATION ON THIS PAGE HAS BEEN OMITTED AND FILED SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO THE OMITTED PORTIONS.

11

Article 12 - Material Breach

In the event of any material breach of its obligations hereunder committed by either of the CONTRACTUAL PARTIES, the other CONTRACTUAL PARTY shall promptly provide written notice to breaching CONTRACTUAL PARTY as to the existence and nature of such material breach. If the breaching CONTRACTUAL PARTY fails to remedy the material breach within sixty (60) days following its receipt of such notice from the other CONTRACTUAL PARTY (or fails to reasonably commence such remedy within sixty (60) days in the event that a complete remediation during such time is not possible), then the other CONTRACTUAL PARTY may immediately terminate this Agreement without any further liability to the other CONTRACTUAL PARTY, including but not limited to ENPHASE’s obligation to purchase the minimum purchase quantities as noted herein, in the event of a material breach by Phoenix Contact.

12

Article 13 - Deficiencies in title

Phoenix Contact warrants that the RESULT developed by it as well as the CONTRACTUAL PRODUCTS are free of any rights of third parties and that the use of the CONTRACTUAL PRODUCTS as well as the RESULT and/or the information of Phoenix Contact does not infringe rights of third parties, especially property rights. Phoenix Contact shall, at its own expense, defend, indemnify, and hold ENPHASE, its employees and agents harmless against all claims, actions and suits for all reasonable and verifiable losses, costs, expenses, damages (including reasonable and verifiable costs and expenses incurred by ENPHASE subcontractors and customers of ENPHASE, to the extent that ENPHASE is responsible for such amounts), claims, demands and/or liabilities (including but not limited to reasonable attorneys’ fees) that result from any actual or alleged (i) infringement or misappropriation of any patent, trademark, copyright, trade secret or other proprietary right by the CONTRACTUAL PRODUCT. For the sake of clarification any costs, expenses and damages that are assessed by a court of law shall be deemed reasonable. For the sake of clarification Phoenix Contact shall have sole authority to retain counsel and defend against such claim, except in the event that ENPHASE subcontractors or customers require legal representation and Phoenix Contact does not agree to counsel and defend such parties. If the use of such CONTRACTUAL PRODUCT is (or in Phoenix Contact’s opinion, is reasonably likely to be) enjoined or otherwise encumbered by such claim, then Phoenix Contact shall at its own discretion either: (a) procure for ENPHASE the right to use such CONTRACTUAL PRODUCT; which allows ENPHASE the right to sell the CONTRACTUAL PRODUCTS to its customers, or, (b) modify such CONTRACTUAL PRODUCT in a manner mutually agreed between the CONTRACTUAL PARTIES so as to avoid any claim of infringement; or, if neither of the foregoing options (a) or (b) is available after using best efforts, then (c) replace such CONTRACTUAL PRODUCT with an equally suitable replacement that is acceptable to ENPHASE and that is free of any infringement. If none of the foregoing options (a), (b) or (c) is available after using best efforts, then Phoenix Contact shall refund to ENPHASE all amounts paid by ENPHASE for such CONTRACTUAL PRODUCTS. The foregoing remedies are nonexclusive.

Phoenix Contact will have no obligation to indemnify ENPHASE, its employees and agents for claims under Sections 11 or 13 to the extent such claims arise due to: (i) ENPHASE’s combination of CONTRACTUAL PRODUCTS or Services with other products; or (ii) the application of the CONTRACTUAL PRODUCT itself, or (iii) ENPHASE’s unauthorized modification of the CONTRACTUAL PRODUCTS; or (iv) ENPHASE’s usage of the CONTRACTUAL PRODUCT in other than the mutually intended use.

13

Article 14 - Limitation of Liability

PHOENIX CONTACT’S LIABILITY FOR DAMAGES RELATING TO EPIDEMIC FAILURE SHALL BE LIMITED TO THE MAXIMUM AMOUNT OF [***] UNITED STATES DOLLARS (US $[***]) PER CALENDAR YEAR.

FOR ALL OTHER DAMAGES, ESPECIALLY BUT NOT LIMITED TO DAMAGES DUE TO QUALITY DEFECTS AND DELAY, EACH CONTRACTUAL PARTY’S AGGREGATE LIABILITY UNDER THIS AGREEMENT IS LIMITED TO THE AMOUNT OF [***] UNITED STATES DOLLARS (US $[***]) PER DAMAGE CASE, UP TO A MAXIMUM AMOUNT OF [***] UNITED STATES DOLLARS (US $[***]) PER CALENDAR YEAR.

THIS SECTION DOES NOT LIMIT EITHER CONTRACTUAL PARTY’S LIABILITY FOR BODILY INJURY OF A PERSON, DEATH, PHYSICAL DAMAGE TO PROPERTY, INTENTIONAL ACTS AND CLAIMS ACCORDING TO THE PRODUCT LIABILITY ACT.

Article 15 - Force Majeure

[***] = CERTAIN INFORMATION ON THIS PAGE HAS BEEN OMITTED AND FILED SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH RESPECT TO THE OMITTED PORTIONS.

14

operational disruptions, strikes, lockouts, official regulations, shortages of raw materials, difficulties in energy supply, mobilization, riots, etc, even if they occur at suppliers of Phoenix Contact or their sub-suppliers.

Article 16 - Coming into effect, duration, other

15

16

Article 17 - Applicable Law/Place of Jurisdiction

17

18