Export tariffs - FIT, SEG, Octopus Outgoing Agile

shibli

So if I am on the Agile outgoing tarrif and have a battery, I assume it's far better to switch off the iboost (use gas - standard tariff), export the excess to the grid, and recharge the battery overnight at a lower rate?

Magnitio

shibli said:

So if I am on the Agile outgoing tarrif and have a battery, I assume it's far better to switch off the iboost and export my excess to the grid and also recharge the battery overnight at a lower rate?

With the export rates being so high at the moment, and for most of us much higher than import rates and considerably higher than gas, then there are options that might help.

For this example, assume rates are: import 35p/kWh; export average 50p/kWh with peak of 70p/kWh between 5:30 and 7:00 PM; gas 8p/kWh.

- turn off the iboost and export the electricity.

- charge the battery from the grid at the cheapest rate available to you. If you are on a flat rate, then charging overnight is sensible from a grid point of view.

- if you have the facility, stop the battery from being discharged during the day. This may mean you are using energy from the grid at 35p/kWh, but the energy stored in the battery has a value of 70p/kWh (see below).

- export from the battery at peak time in the evening.

- if there are times in the day when the export rate is less than 35p then, if you are able to, you can choose these times to charge the battery.

There are some system losses with charging and discharging batteries, so it is only worth doing when there is a significant difference in prices for import and export. Given a 10kWh battery and exporting 6kWh's at peak, the rough value of this would be 6 * 70p - 6 * 35p, less 10% losses = £1.89.

I tried this out yesterday as the export prices were so high. The following graph shows the results of import and export:

Import was between midnight and 3. Export for half-hour slots at 07:30, 16:30, 17:30 and 18:30.

Total export value was £15.62 and import cost £3.62, so profit of £12, but that included all of the solar generation as well.

Was the import and export worth the hassle for an extra £2 ish? Not sure. It also left a very low battery in the evening and one of the reasons for having it is in the event of a power outage.

Screwdriva

Magnitio said:

Was the import and export worth the hassle for an extra £2 ish? Not sure. It also left a very low battery in the evening and one of the reasons for having it is in the event of a power outage.

Not to mention the increase in wear on the battery! Thanks for quantifying this. 

NoobSolar

It does feel very weird suddenly having a reason to go against all the self-consuming strategies I have developed. Today the sun baked my bread, but I should have let the power go back to Octopus. And can I just advise that the people from Marlec replied to my query about turning the iboost off to tell me that : 'The unit is designed to be powered at all times. Switching it on and off regularly will likely have a negative effect on the unit,'.

So this leads me to ask - is there a non-damaging way to pause the activity of a Solar Iboost?

EcoScruples

I don't have access to discharge my battery or even top it up when I want so it's in Max self consumption mode. As the weather has been so good of late it's full by 11am usually and I have the rest of the day to export. So far this month I have exported 172kwh of electric under the agile tariff. That's with filling my battery almost every day apart from those dull days.

I almost stuck with Eon and would have been on a flat 4ppkw, unbelievable.

Magnitio

EcoScruples said:

I don't have access to discharge my battery or even top it up when I want so it's in Max self consumption mode. As the weather has been so good of late it's full by 11am usually and I have the rest of the day to export. So far this month I have exported 172kwh of electric under the agile tariff. That's with filling my battery almost every day apart from those dull days.

I almost stuck with Eon and would have been on a flat 4ppkw, unbelievable.

You still not been provided with access? You can reset the installer password on the inverter - there are instructions in the manual if you are feeling brave.

EricMears

NoobSolar said:So this leads me to ask - is there a non-damaging way to pause the activity of a Solar Iboost?

If the detector is a clamp around the mains feed cable,  you could probably move it to a cable where power is consistently flowing the other way.  But it's probably not very convenient to move the clamp several times a day !

Could you perhaps just put a switch in the lead that connects clamp to control unit ?

Alnat1

I've been playing around with the Agile tariffs like Magnitio but did it slightly differently to suit my system. I've 5.25 on the roof but capped at 3.68, battery only 4.8kW (I want more!)

I stopped the battery charging am (was still around 20%left) and let all the excess go to the grid. As the export prices dropped around 12.30pm I set the battery to charge slowly at 50% rate which allowed me to pull over the cap and fill the battery while still sending plenty to the grid (also used washer/dryer) Battery was full before 4pm when export prices went up. Set battery to discharge to grid at 5.30pm but left myself enough for overnight and am. 

Rates aren't so good tomorrow so I'll let it do it's own thing. Probably only made a couple of quid but it's fun.

QrizB

NoobSolar said:

So this leads me to ask - is there a non-damaging way to pause the activity of a Solar Iboost?

If you don't want to switch off the device, you could fit a switch to the output cable and disconnect it from the immersion heater?

NoobSolar

Qrisb wouldnt that be dangerous? I assume then it would be trying to send energy that couldn't go... Wouldn't that make the iboost malfunction?

I will ask Marlec and let you know what they say when they respond. I love the clamp idea, but I don't quite understand it.