smartphone orten software here handy ortung russland mspy auf iphone 6s Plus installieren spy cam app iphone 6s Plus handy kindersicherung internet vergleich sms spy yahoo
Skip navigation.
... for greater sustainability and local resilience

Renewable Energy Directory

Free entries for Cornwall based renewable energy suppliers. Just add a 'comment' describing your local business or use the 'contact' form to email in the information to be published.

To add an item click on 'add new comment'
To reply to an item, click on 'reply' at the bottom of the item

PaulS's picture

EMMA allows you to soak up all your renewable energy

Emma is piece of equipment to ensure that the maximum amount of your own renewable energy stays in your house and does useful work, rather than being exported into the Grid, only to be later imported from the Grid at a much higher cost.

Here is how it works. See website link for more info.

In brief:

Suitable for Single Phase (SP) connections

The primary load must be equal to or less than the supply to the EMMA (i.e. if there is a 3kW supply to EMMA, the primary load must be 3kW or less).

The EMMA CASCADE model numbers reflect its range in size from SP15 to SP15/30, SP15/45, SP15/60, SP15/75, SP15/90, SP15/105, SP15/120 and, the largest, the SP15/135.

The size of the EMMA unit is determined by the number and size of the heating elements you use. So to determine what size EMMA you require you need to determine what immersions you are using / intend to use. The names of the units indicate the size of a heat load they will work up to.

Cost: from £2000

Getting and installing your EMMA

Where can I get an EMMA?

Have a look at our reseller map to find a supplier in your area. They will have pricing information for you. Alternatively, if you have an existing supplier of your PV/wind system, you could ask them to contact us at this email address and we may be able to set them up as a supplier. That way you get to have one point of contact for supply and installation.

How much does EMMA cost?

See our Prices page.

How long does shipping take?

Once your EMMA is in stock, shipping is two days to major areas in Ireland and UK. Any post codes out of the way will take longer to deliver in the UK.

What advantages does solar PV and EMMA have over solar thermal?

See our Prices page.

I installed/ordered my generator before I heard about EMMA. How can I get an EMMA with it?

EMMA is easily retro-fitted, so if your installation is imminent you can always go ahead with it and ask your supplier to get in touch with us so they can supply and fit an EMMA for you afterwards. If possible, get your installer to contact us before your generator is installed so our engineers can brief them on preparing the wiring and mounts for EMMA so it is more quickly slotted in afterwards. We recommend that you ask your reseller to place an order for EMMA asap as demand for EMMA is such that we occasionally have a waiting list.

What size is EMMA?

The dimensions of each EMMA unit are 375mm wide x 182mm high x 184mm deep.

Where should I install it?

In any cool dry place that remains below 30 degrees. Typically under a fuse board. It is possible to fit EMMA units remotely from the consumer unit using long CT leads. It can be fitted beside the hot water cylinder, for example, providing that you can run the CT leads back to the incoming tails from the grid and the inverter.

How long does EMMA take to install?

The average install takes 4 hours on a retrofit and about 2.5 hours on an installation with the PV/turbine going in at the same time. For electricians who have installed EMMA before it takes less time. The reason for the time difference is the rearranging of the inverter connection through the Henley block for the correct configuration of the CTs.

Back to Top

Using EMMA

What does EMMA stand for?

Energy and Microgenerator MAnager. When EMMA was originally designed it was intended to work with domestic-size microgenerators of around 3kW, hence the name. Since then it has been extended to work with micro, small, medium and large generators - and you can control loads of up to 300 kW.

How does EMMA work, in brief?

EMMA has the unique patented ability to send anything from 0W to 3,000W to a 3kW immersion heater in real time. It is fitted with two CTs (current transducers) that enable it to monitor and compare the output from your renewable generator (e.g. solar PV, wind turbine or water turbine) and the demand of your household (including the demand of your immersion heater) in real time. It uses this information to adjust the amount of power being sent to the immersion heater from 0% to 100%, also in real time. By doing this it ensures that total household demand matches the output from the generator precisely at all times when the generator's production would otherwise exceed the household demand.

When the output from the generator exceeds household demand, EMMA increases the amount of electricity going to the immersion heater. This in effect brings household demand up to match generator output.
When household demand exceeds the amount of electricity being produced by the generator, EMMA reduces the amount of electricity being sent to the immersion, and if necessary allows grid electricity to be imported to meet household demand.
Example: If your PV system is generating 3kW and your household is consuming 2kW, EMMA will send the remaining 1kW to your immersion heater.
EMMA in effect puts all the surplus generator output into the hot water cylinder (or other heating/cooling loads in the houseshold, as you wish). This is typically 50-70% of the total generator output. During much of the time you are effectively getting free hot water.

Can I use EMMA to charge batteries?

In the case of battery charging we would need to determine if the charger will function with PWM controlled input. If it doesn't we could provide a 0-10V DC control output that can be used to adjust the chargeing rate. This will require a charger that can take a 0-10V DC control input. Contact your Reseller with the details of what you wish to do and as necessary we will assist them with the design of a solution for you.

Back to Top

EMMA and your immersion

Does EMMA give me additional control over my immersion?

Yes. In addition to the above functions, EMMA acts as an advanced time and temperature based controller for your hot water cylinder. It will ensure that the hot water reaches a menu set minimum desired temperature during pre-set time periods (two per day), drawing the minimum amount of power required from the grid to do this on days when there is little or no PV output. The hot water timer allows for two heating periods per day. Hot water boost is on demand. It also has a holiday schedule and maximum safe temperature setting to ensure that the system switched off at the beginning of the holiday and back on at the end and to ensure that the system doesn't overheat on exceptionally sunny days.

I don't want any power going to the water tank except for frost protection. Can I do this?

Yes. You can set the max safe temperature to 5 degrees to achieve this. You will need your EMMA unit to switch over to a secondary load when the tank temperature reaches 5 degrees... and vice-versa. Depending on the version of EMMA you have, it may be possible to reduce the minimum setting for the minimum desired temperature to 3 degrees. If you set this to 3 degrees and set the schedule to 24/7 you will get the frost protection you are looking for.

What if my immersion is 3kW but my generator is only producing 2kW? Will an EMMA send just 2kw to my immersion heater when PVs are only generating 2kw even though my immersion heater is 3kw, or does EMMA wait until at least 3kw is being generated by PVs before sending power to my immersion?

EMMA will match any excess power from your PV array above your household demand and send it to your immersion. EMMA can vary the power from 0 to 3kW. It can send 2kW to a 3kW immersion as you have indicated. It will not wait for 3kW to be produced before switching on, If there is 10watts available above what you are using in your house then 10 watts will be sent to the 3kW immersion. The immersion will still work fine.

You mention that EMMA also results in savings because of reduced heat losses from the immersion?

Yes. One of the unexpected benefits from using EMMA is significantly reduced heat losses from the hot water cylinder. This is the result of EMMA 'trickle charging' the hot water cylinder for most of the time (i.e. operating the immersion heater at low outputs) and thereby preventing wasteful convection driven 'churning' that occurs when the immersion heater is operated at full power. We have observed this reducing losses from hot water cylinders by up to 50%.

Does the immersion heater need to be on constantly if it is to be controlled by EMMA?

Yes. EMMA will turn it on and off then depending on the available electricity and your heating requirements.

Is it possible to run my immersion only when surplus electricity is available, and program it so that it never uses grid electricity for hot water?

Yes. EMMA allows you to set times when you want definitely want the hot water to be at or above a minimum desired temperature. These times are typically at 7.00 am to 8.00 am and 5.30 pm to 9.30 pm. EMMA then ensures that the hot water is brought up to this temperature for these time periods - with the help of mains electricity if necessary.

If you never want to use mains electricity for hot water, you just set these heating periods to run from 7am to 7am and 6pm to 6pm or equivalent. In other words, you are setting the defined hot water heating periods to zero. EMMA will now heat the water towards a target temperature when surplus electricity is available, but will never draw grid electricity to heat it. These settings can be changed at any time.

What would happen if EMMA's heat sensor failed - would EMMA continue to send excess power to the immersion and if so would the tank start boiling or is there a fail safe device to prevent this?

The existing immersion heater thermostat(s) act as the fail-safe safety device in the event of the EMMA sensor failing. The EMMA sensors are solid state thermistors type units. They are extremely reliable.

Can you advise me on which immersion heater to buy?

We cannot advise on sizing or designing of cylinders as that is not our area of expertise. However, EMMA will work with any standard electric immersion element, but each load should be a max 3kW. For instance, if you want a 9kW immersion in total, then use three 3kW immersion elements rather than a single 9kW element.