Ring main from spare position in Photovoltaic Consu Unit?

[Stinsy]

If you have a Zappi then it's a no-brainer you should get an Eddi because the two will communicate. But all solar diverters (that I know of) can also be programmed to use cheap overnight power in addition to diverting excess solar.

[Adokforme]

Thanks Stinsy, you're a star! Something else to ponder.

[Countrypaul]

Thanks again for information and explanations both. Food for thought then before making a final decision. It's much appreciated.
Either way an FCU appears the way ahead, or an E7 controller for cheaper overnight tariff use. Although unsure if this can then be used with a diverter or whether it's an either or situation. If it's the latter then could I have one element on E7, for Octopus Go, and the second controlled by a diverter?
We do have a Zappi, but I was not aware it could be set up as you describe. It works great at mopping up much of the surplus, but as you correctly point out there are times when the BEV is fully charged. Not that I mind that too much!

Depending on where you locate you Eddi, it can link to both immersions (one at the top of your TS and one near the bottom), it would first divert to the top and when that hit target temperature divert to the bottom. Each immerison needs a separate connection to the Eddi (fairly obvious but...), if you have the Eddi beside the TS then you only need one supply from the CU as the Eddi can only run one immersion at a time - and you should never backfeed into the Eddi. If you have the Eddi near the CU then you will need two supply cables from the Eddi to the immersions but still only one to the Eddi. If you are unsure at this time put 2 in you can always change you mind later and only use one.

The Eddi supports timers so can also be set to come on at whatever time you require, during winter ours if often set for the top immersion to come on for the last hour of E7.

The Eddi also supports the use of a relay board (additional item) that can also switch a load upto 16A (so it could switch a second immersion heater) this would require a separate supply to the relay from the CU and from the Eddi to the immersion (another good reason to put 2 cables in!) so would allow you
to have both immersions on at the same time if you wanted.

Do you have any other heat input to the TS, or is it only immersion heaters?

[Adokforme]

Depending on where you locate you Eddi, it can link to both immersions (one at the top of your TS and one near the bottom), it would first divert to the top and when that hit target temperature divert to the bottom. Each immerison needs a separate connection to the Eddi (fairly obvious but...), if you have the Eddi beside the TS then you only need one supply from the CU as the Eddi can only run one immersion at a time - and you should never backfeed into the Eddi. If you have the Eddi near the CU then you will need two supply cables from the Eddi to the immersions but still only one to the Eddi. If you are unsure at this time put 2 in you can always change you mind later and only use one.

The Eddi supports timers so can also be set to come on at whatever time you require, during winter ours if often set for the top immersion to come on for the last hour of E7.

The Eddi also supports the use of a relay board (additional item) that can also switch a load upto 16A (so it could switch a second immersion heater) this would require a separate supply to the relay from the CU and from the Eddi to the immersion (another good reason to put 2 cables in!) so would allow you
to have both immersions on at the same time if you wanted.

Do you have any other heat input to the TS, or is it only immersion heaters?

Hi CP, thanks indeed for sharing all that info, it really is very good of you to take the time and is much appreciated.

There is no other heat input into the TS. We finally transitioned away from FF's a year ago, so all our domestic and transport requirements are now provided by leccy from renewable sources.
Blame Mart, he started it all.

[Countrypaul]

I thought you might have another source of heat such as a heat pump. You may have read in another thread where I explained our setup with a thermal store at the centre and to an ASHP heat the store but also an immersion to heat the higher part of the store for DHW.

I don't know your heat requirement, or your emitters, but a heat pump (ASHP or GSHP) could possibly provide you with 3 times the amount of heat you get from resistive heating for the same amount of electricity - leaving more for your wheels

[Adokforme]

I thought you might have another source of heat such as a heat pump.

Apologies CP, the TS has no other form of heating, but our bungalow is covered by two air to air source heat pumps. Installed after following a thread on the MSE website. Perhaps you contributed to it? Anyway, kept the radiators for a couple of winters in case the pumps weren't up to the job, throttled back on the GCH until this last one when we didn't use it at all. Since then the TS has been served by Solar or the cheaper overnight rate on Octopus Go during the darkest months.
Considering how cold some of the temperatures reached during the last winter & spring the heat pumps stood up to the task, in spite of others suggesting that they don't work in sub zero temperatures!

[Stinsy]

I thought you might have another source of heat such as a heat pump.

Apologies CP, the TS has no other form of heating, but our bungalow is covered by two air to air source heat pumps. Installed after following a thread on the MSE website. Perhaps you contributed to it? Anyway, kept the radiators for a couple of winters in case the pumps weren't up to the job, throttled back on the GCH until this last one when we didn't use it at all. Since then the TS has been served by Solar or the cheaper overnight rate on Octopus Go during the darkest months.
Considering how cold some of the temperatures reached during the last winter & spring the heat pumps stood up to the task, in spite of others suggesting that they don't work in sub zero temperatures!

That is very cool!

I've been thinking about an air-to-air HP to augment my GCH. There is a nice place for it on the upstairs landing and I could mount the outside unit on the back (south facing) wall. The Idea would be for the HP to do the heavy lifting during the 2030-0030 Go-Faster cheap rate period. I've seen "easy fit" 3.5kW units available for around £600 with all the pipes/mountings/etc. While these are sold as "DIY" in other countries (they sell them in the supermarket in some countries!), and I know of people who've installed them themselves, most sellers require the details of your F-gas installer before they'll ship it.

How powerful are yours?
Did you install them yourself?
How did the Mrs react to slightly warm moving air?

[Adokforme]

How powerful are yours?

2kW each(output that is, input circa 400- 500W measured at socket )

Did you install them yourself?

Nope, I was recommended a local installer, he wasn't the cheapest but living within a mile of us, installing only top of the range units and offering a five year parts and labour guarantee we had the first one installed in Oct '18 and being sufficiently impressed, the second in the December.

How did the Mrs react to slightly warm moving air?

Could have been a problem, but they are so versatile with a variety of air speeds and directions, up or down, left, central or right or combinations of all. It didn't take long to find the settings that best suited us.
I've seen them advertised, installed,for as little as the £1k mark each. Ours were half as much again but felt it money well spent.

As for Cool, you hit the nail on the head there. In summer with excesses of solar you get free cooling into the bargain.

It was Mart who put me onto them and I add a link to an MSE thread below if you want some bedtime reading. There's forty odd pages to it but a fascinating topic and originally planned for use with solar pv in the shoulder months. I think I've stretched there usefulness a little further.
Oh our bungalow is approx 100sq metres floor area. Of course a two storey house is a different matter. One up on the landing, great for heating upstairs in winter and sending cooling air down in summer!


https://forums.moneysavingexpert.com/di ... olar-pv/p1

[Stinsy]

Thanks for the info! Total of 4kW heating your whole bungalow is interesting. The gas boiler you removed/nolonger use will probably be 11kW or something in that ballpark! Have you done much work on the insulation or is it pretty standard?

I have a 5-bed house with 2 adults, 2 kids, and a dog. I also "only" have 4kWp of solar. So you have more than double the solar I have and probably half the heating requirement (we have a 30kW boiler). Therefore I'm not surprised you manage to heat your home in the shoulder months and cool it in the summer with your self-generated electricity!

I'm considering more of a "baby step" whereby I augment my boiler with a "1.1kW in / 3.5kW out" air-to-air that runs during the Go-faster 2030-0030 period. This gets particularly attractive if the price of gas rises much above 5p/kWh.

[Adokforme]

Thanks for the info! Total of 4kW heating your whole bungalow is interesting. The gas boiler you removed/nolonger use will probably be 11kW or something in that ballpark! Have you done much work on the insulation or is it pretty standard?

Yes, 4kW is hard to imagine isn't it. Especially when the GCH was a 30KW Ideal Logic + Combi. Admittedly it would just be on for a couple of hours in the morning and about five or six in the evening. In severe cold it was on all day, but not overnight.
Our Go Faster tariff is from 01.30 to 06.30 so, in winter, set the ashp's to come around 04.00 and leave on till almost bedtime.
Insulation wise, 30cms in the loft plus cavity wall. Double glazed windows, then thermal blinds & curtains on north facing aspect but translucent(same as thermal but without alumium foil internally) blinds & curtains on south and west. No windows east.
Checking back on this last winters figures, I have an energy monitor on each ashp, then for the five months Jan to April they consumed 1546 kWh's total. Some of which being at the cheap rate(they consume more on start up than once up and running) and a small portion from solar. With a COP of approx 4 then an output of around 6.2 MW's.
Lounge, bathroom and Lobby(that's where the second unit is) maintained at a minimum of 21C. Two bedrooms, hall and kitchen 16C.
They work in the layout of our property but accept they probably won't suit all. With a COP of 4 then the cost of the leccy isn't far away from that of gas. And of course with GCH there is the hidden leccy cost of driving the fan in the output of a condensing boiler and also the circulating pump. We've also managed to lose that annoying standing daily charge for gas which amounted to around £70/yr.