Coolpower EMMA

nande2000

Has anyone who has a small domestic solar pv array (less than 4kw) installed a Coolpower EMMA 3G (Energy and Micro-Generator Manager)? They look like an excellent idea, but many blogs say they are a bit pricey, i've heard mention £1500+ to install. Are they cost effective ?

Cardew

There has been discussion on these devices in the 'Green' forum.

It is the 'holy grail' for many people to utilize as much of their PV generated electricity in their house. An average figure for savings is probably around £100 a year.

In the unlikely event that EMMA could use an additional 50% of that generated electricity, the savings of £50 would never justify such expenditure on EMMA.

The other consideration is how will that electricity be used in the house? The obvious candidate is water/space heating. However if you have gas/oil/E7 for heating then your savings are only at the rate that fuel costs. i.e. a kWh of PV generated electricity utilized by an immersion heater will save you around 4 pence if you have gas.

nande2000

Ok so, first i'm on Oil. No mains gas and my oil boiler is say 70% efficient (at best) based on the flue pipe test. Given it's an old range cooker boiler and allowing for pipe wastage I reckon im seeing 50% boiler efficiency overall. At current oil prices thats on a par with electric costs.

If the EMMA works as the sales pitch says i think I will save £360 per year (based on electric prices). I have a 3.96kw pv system and im today im probably using 30% of the electric produced in the day, this also takes into account that im going to get a thermal store (so thermostat can be set to 90 degrees on the immersion). Sounds like a 4-5 year payback to me.

I know a lot of people would say use the money to invest in a new efficient oil boiler, but I think thats pointless as the only way is up for oil...I'm going to convert the range to SF this summer as I have lots and lots of free wood.

Cardew

Well with oil CH and a boiler operating at 50% efficiency, you would do well to consider an Economy 7 tariff with off-peak for your thermal store at around 5p/kWh.

When you need a large thermal store(in winter) PV output is low, in summer why do you need a large enough thermal store to 'use up' electricity.

How much will the thermal store cost to install and commission - in addition to EMMA?

If your calculations work out - then go for it! However I suggest it would work for the majority of people.

nande2000

Thats a very good point and not an option I had considered. Are there any costs associated with moving to economy 7 ? Is the PV FIT effected if you move to it ?

To fit and install a vented thermal store I reckon about £3k
:money:

nande2000

Just had a quote from Edge renewables to supply and fit the EMMA. £1875 plus vat. Thats far too expensive. I cant believe its that hard to install so it may be a case of waiting til the price of the unit comes down.

thenudeone

nande2000 wrote: »

Are there any costs associated with moving to economy 7 ? Is the PV FIT effected if you move to it

I have economy 7 and solar panels.

It make no difference to FIT what tariff/meter you are on because the only readings required are the generation meter.

It may cost something to change a standard meter for an e7 meter, you need to ask your local elec. distribution company.