In my current place (Morocco), the electrical utility operator does not allow feed-in. How can I create a photovoltaics installation that respects this rule? I would like to create a grid-tied installation so that grid power can be used when locally produced power is not sufficient.

Details: feed-in regulation in Morocco

The utility operator does not offer net-metering or a feed-in rate for electricity produced by a residential photovoltaics installation. (Net metering is offered for plants connected to the high-voltage network, with the rest planned in laws but not implemented yet – see.)

So, no feed-in program is offered and the power company does not allow feed-in. The typical solution here (accepted by the utility) is a manual transfer switch so that an installation functions either as off-grid installation during the day, or as normal AC-connected household without own production during the night.

This solution needs buffer batteries though, an inconvenient manual transfer twice daily, and a relatively large inverter as it has to cover all loads in the house. Also, the switch will first switch to a neutral position before switching over, disconnecting everything in the house for a moment.

I hope there are other options?

  • 1
    Where I live only qualified technicians are allowed to make modifications to the electricity supply. So before you do anything I'd advise you to check if you are allowed to make modifications yourself. Also check what your insurance has to say about it. – THelper Mar 28 at 13:44
  • Where do you live? Often local distributors of international brands will provide versions of inverters that meet local utility requirements. Or, a local manufacturer may have a product that larger brands wouldn't sell in isolated local markets. – LShaver Mar 28 at 13:53
  • @LShaver This is about Morocco. Finding an inverter configured specifically for the Moroccan market seems difficult, but I'll look further. – tanius Mar 28 at 14:14
  • 2
    If you have a hot water cylinder then often it's better to dump excess power into that than feed back to the grid. – Graham Chiu Mar 28 at 18:38
up vote 3 down vote accepted

Where feed-in is forbidden, a normal grid-tie inverter is not acceptable to the utility. (For the various cases of feed-in regulation, see this question.) However, an inverter plus a zero export solution can be acceptable. I propose to use this (options listed below), as it gets around the need for batteries (which are an additional expense and incur replacement costs due to normal degradation).

So, simply ask the utility operator. They often have lists of equipment that may be installed legally, or if not, may accept your proposed equipment on a case-by-case basis.

(In some countries, utilities may not yet have heard about zero export solutions, but a local electrician might agree to install an inverter with zero-export since it does not affect the grid. This is technically true if the inverter also has the anti-islanding feature (switching off when the grid goes down, to protect line workers; most grid-tie inverters have it, some reportedly don't, so check before). However, even if the local electrician offers this, as it happened to me, it is probably not "according to the letter of the law". Proceed at your own responsibility, as always.)

All options I list below also allow export limiting to a non-zero value, for cases where that is acceptable.

1. String inverter(s) with export limiting

This is the most usual / standard alternative. Many current inverter models support export limiting, and if they do, usually also a "zero export" mode and sometimes a "minimum consumption" mode (a less-than-zero export limit). But check the manual of course. Example products include:

  • SolarEdge inverters. Their export-limiting solution seems an esp. nice alterative, as they all work with a simple S0 electricity meter (no expensive smart meter required) (see), and configuration can happen with buttons on the device (see the manual). A web-based interface is also offered, though. Inverter size starts with 1-phase 2.2 kW inverters (see products with prices). Note that SolarEdge inverters differ from others in that the MPPT (DC-DC conversion) part is in separate devices close to the panels, called Power Optimizers, which you will need in addition. But it offers the advantage that you can mix all kinds of panels of different types, ages and brands without losses, as each panel's output voltage is kept constant and each panel is driven at its maximum power point due to the separate MPPT devices.

  • Fronius SnapINverter. With integrated feature "Fronius Datamanager 2.0", plus a Fronius Smart Meter. See their presentation. Also supports minimum consumption mode, called "Grid setpoint" (see chp. 4.3.12). See also the list of compatible inverters. Configuration of export limiting happens via a web interface, which may not be desired in some circumstances …

  • Fronius SnapINverter and Victron Venus. This combines a Fronius SnapINverter, as above, with a Victron Venus controller and a Victron smart meter. Export limiting is possible:

    It is possible to make a Zero feed-in system with Victron & Fronius. The Venus device will the control the Fronius output power. (source)

    Venus is open source software and even runs on a Raspberry Pi, so this might be a good solution where own modifications of the control software are desired.

  • Zeus Appollo Solar Anti Reverse Current Box. Only compatible with their own Zeus Apollo Z20 Series inverters, so listed here under inverters.

  • SMA inverters with either the SMA Sunny Home Manager or the SMA Cluster controller allow to create a zero-export solution (see).

2. Micro-inverters with export limiting

Not a usual option, but possible. Micro inverters provide the same advantage as SolarEdge inverters: panels of different age, type and manufacturer can be mixed as the output is normalized (here, to grid AC electricity). Options found:

  • Enphase. According to a lengthy forum discussion, the Enphase micro-inverters supporting this so far are the Enphase S230 and S280, together with the "Envoy-S metered" controller. Of these, only the S230 comes in a 50 Hz version, and would have to be imported from Australia (see posts #19, #28, #46).

  • SolarFighter. A Spanish company providing a very nice zero-export solution built around a 250 W microinverter, a smart meter and a controller box (see). Up to 25 microinverters (6.25 kW(p)) can be combined with the same controller box and meter (see). All devices are sold both separately and as kits, and the minimum investment is ca. 530 EUR for all three devices excl. PV panels (see).

    The problem with this solution is that the zero export feature does not seem to work as advertised, according to my own tests. The controller box will set the production limit values in the inverter correctly, but for every value >20 W the inverter will produce unthrottled, while for every value ≤20 W it will not produce anything. SolarFighter support confirmed that the behavior is not normal and exchanged the inverter on warranty, but so far the problem persists. This is esp. sad as otherwise this would be the only accessible zero-export solution for small installations. And all residential installations in countries where export to the grid is forbidden are small (<1 kW(p)) – simply because more generation capacity than needed by the household cannot be utilized.

3. Zero export devices

These are dedicated devices that can control the power output of a limited set of inverter models, externally adding a "zero export" feature to them.

  • Circutor Dynamic Power Controller CDP-0 / CDP-G. A combination of electricity meter and controller that can adjust throttle inverters of many different brands to limit or eliminate exporting power to the grid. The CDP-G version also includes three relays to power non-critical electrical consumers before having to throttle the inverter (see the datashee). Nice and compact device. Readily available in Europe for ca. 800 EUR (see); that price makes it only economically meaningful for larger installations.

  • elgris ZERO EXPORT. The principle of function, if I understood it correctly, is in case of "overproduction" to first increase local consumption (like of a water heater) and, if not enough, to reduce the inverter's production. It is said to be inverter model independent and able to throttle inverters and not just switch them on and off. No price or convenient purchase option found, though.

  • Solar Zero Export Controller. Able to throttle inverters of multiple brands in order to achieve zero export. Namely, works with various models from Schneider, ABB, Fronius, Delta and SMA.

  • PicoGrid ZX. Made for photovoltaics installations of 5-100 kW(p), and seemingly requiring a special inverter to interface with (not sure yet, though).

  • ComAP InteliPro PV. Seemingly made for larger installations.

  • carbonTRACK. An energy control solution with export limit functions. Not sure what inverters can be connected to it.

  • GNT Engineering Zero Export Device ZED 1. No longer a suitable option because "GNT Engineering have ceased operations and the ZED 1 is no longer commercially available." (source).

    This was a device that could control up to 6 inverters, thereby controlling the amount of power produced and ensuring zero export. Control happens via "selective switching or 4-bit binary control" (source). In addition to 4-bit digital control it can also use 6-bit control and RS485 (source), making it compatible with many brands of inverters.

    "Selective switching" simply means to open a switch in the inverter's output connection, thereby turning off generation immediately. This shuld not hurt any inverter, since they are prepare for grid failure to happen ("anti-islanding function" etc.). This control mode works with all inverter models, but does not allow it to throttle inverters. So if your self-consumption is usually smaller than the smallest inverter you have, your photovoltaics installation would not be used at all. It is better to use inverters that can be throttled by this device.

4. Increasing self-consumption

There is, to my knowledge, no certified industrial device that uses increased self-consumption as the only way to guarantee zero or limited export to the grid, so this is NOT an acceptable solution with respect to regulation where feed-in is forbidden.

However, some of the solutions mentioned above have the option to control the consumption of non-critical electrical consumers (like a water heater), and there are DIY ways for that as well. So it is a useful addition to throttling inverters, as it utilizes the "oversupply" electricity meaningfully. This is best discussed in another question.

5. Supercap buffering with automated transfer switching

This is an own idea and so far my favourite proposal because it is cheaper (esp. for small installations <1 kW(p)), more do-it-yourself, and more maintainable. A small-ish supercapacitor bank is recharged by photovoltaics panels and the house runs either on the grid or from that supercap bank via a cheap, non-grid-tie inverter. An automatic transfer switch switches over seamlessly every few minutes.

I explore the idea in detail here: "A DIY solution for photovoltaics self-consumption".

  • "Batteries... tend to break." It would be more accurate to say they degrade over time, requiring ongoing maintenance costs. Also, it's not true to say that all grid-tie inverters come with anti-islanding. – LShaver Mar 30 at 18:11
  • @LShaver Good points, fixed both in the text now. – tanius Mar 30 at 18:39

My advice would be to use a solar + battery setup. The battery storage would take up the slack in times when demand is greater than solar supply. During the day, when the batteries are charged, the excess can be dumped into hot water. You would only require grid power to top up your battery if there is any shortfall in solar supply. You don't necessarily require a large battery bank. A couple of days worth could work depending on your needs and budget.

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