Solar Exported Today

[RagingWhisky]

do you know roughly what kwhs you'd need for heating and h/w? you could move one away from oil initially depending on what excess electric you may have (or what off peak you can harness wiht battery).

H/W you could look at something like a sunamp or mixergy for trickle charging, leaving only heating to oil. And can be fun to at least do a review on heat loss etc to see if an ASHP would work for you for heating given your current rooms/insulation/radiators. Or possibly Air to air with wall mounted units? Would give similar COP as a big 'whole home' ASHP

9kWh Sunamp Thermino (hot water/ showers and baths)
12 radiators stripped out and gone full electri with those (wasn't going anywhere near air or ground source air-to-water heatpumps - figured get rid of the water based heating and go all in).

On a single phase, 24panel 9.7kWh PV / 17+ kWh battery (to be expanded) - 6000watt discharge continously max on the battery (going up to 12000 shortly with the expanded storage)

Gas only gets used for fireplace and hob cooking (for now).

Seems to all work (touch wood)

 

[barry.perfect]

9kWh Sunamp Thermino (hot water/ showers and baths)
12 radiators stripped out and gone full electri with those (wasn't going anywhere near air or ground source air-to-water heatpumps - figured get rid of the water based heating and go all in).

On a single phase, 24panel 9.7kWh PV / 17+ kWh battery (to be expanded) - 6000watt discharge continously max on the battery (going up to 12000 shortly with the expanded storage)

Gas only gets used for fireplace and hob cooking (for now).

Seems to all work (touch wood)

Would be interested to hear what you replaced the radiators with?

Also, where did you put the Sunamp? Thinking of replacing our immersion heater with one, but not much spare space unless we put it in the garage, then there is potentially lots of expensive plumbing to worry about.

 

[Dilly]

Our dogs have a room, with outside door. The door from that to house is "sealed", so the dogs can have their door open without effecting balance of MVHR to rest of house ... dunno if your arrangement would allow that though. It suits us because the inner door is basically an external door, and has a proper lock. So when we go out we lock the inner door, leave the dogs outer door closed, but unlocked, and if we are unexpectedly delayed we can ask neighbours to rescue the dogs!

MVHR needs to be balanced - I'm sure obvious, but if the house leaks air somewhere then the exhaust air going through the MVHR is less than incoming ... and heat transfer is diminished. That apart, leaving doors / windows open is fine, it is just not a good idea at times when you would like to preserve the temperature of the house - i.e. it is either blinking cold outside, or blinking hot. At those times keeping everything shut is helpful to maintain the temperature, but that apart opening everything is fine. We use evening-venting in heatwave to cool the house. It isn't hot, but it will become hot over the course of 7 - 14 days prolonged heat if we do nothing ... and then the heat is quite hard to get rid of Natch! so at such times we cool it by opening windows of an evening. Cool air comes in, room temperature drops, fabric of the house absorbs that "coolness" ... then we close the windows, and the room temperature immediately bounces back! 'coz substantively altering the temperature of the fabric of the building takes a lot of Therms. A good thing, for constant temperature maintenance, but a nuisance if the house gets either very hot or cold - takes a lot of effort to get it back again

When we have guests in Summer it is quite common for them to throw the windows open in the morning <sigh>. Net effect the room heats up, and they will be too hot tonight. The ducted air is pumping through as much fresh air in a day as an open window for a few hours would do, so there is no need. But people think it weird that we don't routinely open windows ... personally I'd like to keep all the flies etc. out of the house ... and the pollen and dust.



Understood; we too did ours when it died (in 2008) and needed replacing anyway. I'm retirement age now and glad I had all that disruption back then

Dogs have the run of the main bungalow but not the annex. Only the utility room has a usable door for dogs but, it’s at the front of the house and opens onto the common! Given all the rabbits, they’ve already proved, once out of the door, they’re off! On;y the conservatory opens directly into our secure back garden.
We’re lucky with the boiler. It’s 19 years old and was a prototype built locally by Merlin. Their MD and chief designer worked closely In developing it with a close friend of ours who was our service engineer. Our existing boiler was on it’s last legs and we became the test bed. There were about ten early revisions to it. At the time it was pretty frugal, it still is and it’s still going strong.

 

[RagingWhisky]

Would be interested to hear what you replaced the radiators with?

Also, where did you put the Sunamp? Thinking of replacing our immersion heater with one, but not much spare space unless we put it in the garage, then there is potentially lots of expensive plumbing to worry about.

Exactly where the hot water cylinder was (before and after).

Boiler ripped out, no hot water tank, no need for pumps and eadiators all stripped off.

Replaced: Elkatherm rad units (all individually app controllable so you only heat the rooms you need when you need).

Heatpumps never really won me over, so went down this route instead.

 

[Mrklaw]

the potential issue with straight resistive electric rads is 100% efficiency vs 300-500% with ASHP (either wet radiator system or air to air like regular air conditioners). If you have the excess solar/battery that might not be an issue, but heating demand would be highest in the lowest solar months.

 

[Drew57]

we lose quite a bit through our conservatory overnight, which is 4 years old. That’s because the inner patio door to the lounge is left open.

We had exactly that until 2019 when we employed a builder to integrate the conservatory into a larger space incorporating the former dining room and kitchen. The roof was replaced, triple insulated & tiled and initially the plan was to just upgrade the double glazing windows and doors but we were encouraged to switch to argon filled glass with integral blinds. Even without an internal door barrier the space remains warm in all seasons whereas previously it was too cold to use in winter & far too hot during much of the summer (SSW facing). It has been a great investment and significantly reduced the house's single largest energy loss (Octopus FLIR camera scheme)

 

[Dilly]

We had exactly that until 2019 when we employed a builder to integrate the conservatory into a larger space incorporating the former dining room and kitchen. The roof was replaced, triple insulated & initially the plan was to just upgrade the double glazing but we were encouraged to switch to argon filled glass with integral blinds. Even without an internal door barrier the space remains warm in all seasons whereas previously it was too cold to use in winter & far too hot during much of the summer (SSW facing). It has been a great investment and significantly reduced the house's single largest energy loss (Octopus FLIR camera scheme)

We don’t have roof blinds, it’s more an orangery so there is a partial ceiling all the way round. We do have blinds all the way round the sides except the doors and the units are argon filled. There are a few days each year where it’s too cold and perhaps twice as many hot days. Otherwise we spend every day in it.
my wife fought against one for years because it would be too hot. It only is when when we get to 30 degrees! It’s the best room out of the house

 

[Drew57]

We don’t have roof blinds, it’s more an orangery so there is a partial ceiling all the way round.

Aplogies, my post must have implied that so I've edited & corrected it. The ceiling is now triple insulated and tiled, it's only the walls and doors that are glass.

 

[RagingWhisky]

the potential issue with straight resistive electric rads is 100% efficiency vs 300-500% with ASHP (either wet radiator system or air to air like regular air conditioners). If you have the excess solar/battery that might not be an issue, but heating demand would be highest in the lowest solar months.

Very fair comment on efficiencies - essentially just comes down to your own domestic/personal use cases and requirements (and where you're able and lucky for the space!).

For the radiators, because they individually heat up 'so quickly' (short sharp power draw per unit within 5 minutes to become 'hot and ready') they retain that heat and dissipate to the room pretty seamlessly. There _IS_ obviously a higher initial draw (some of the bigger bedroom/living room units can be 3kWh draw just on their own for one room), but its only for 5-10minutes 'top up' per hour if you had them running full bore.

The trade-off compared to AS/GS-heatpumps, is that rather than heating your entire wet-central heating system, you've now inherently got individual radiator control (app based in this instance, but other makes/model approaches available), less reliance on the pipes in your home (yay! no bleeding radiators ever again!) and no need for the initial air-source unit on the side of your home and/or digging up the garden and/or hooking up to your existing heating system!

As an important note: we do have air-conditioning fitted, with a Daikin heatpump unit wallmounted outside, going to fan coil units in the bedrooms (so essentially air-to-air heat pump goodness), but the thinking there wasn't about heating but cooling as UK summers keep catching us out!) - fascinating watching the load in the house 'only' go up 300-400watts when that's experimenting on running maxxed out to cool all rooms to 17-18c, so its certainly damned impressive on power draw efficiency.

As a bonus, as we aren't using central heating via water for 'radiator heat into the rooms', the sunamp only needed to cover all bathroom/shower/tap duties (insanely hot if you up it to maximum - I believe the hype of '65C and above capability!):

1. This is without the need for any hot water tanks
2. No immersion heaters to top up any ASHP/GSHP water temperatures
3. Once the unit is 'charged' (9kWh storage capacity for my model) it holds that 'charge' for 10 days+ effectively before meaningful 'top-up' required - not that i recommend going without a shower/bath/hot taps for that long
4. Gave us mains pressure hot water (the dream!)
5. No water pumps for the shower (great if you're not wanting to wake anyone sleeping)
6. Damned compact!

My main takeaway from all of the above is that its highly subjective, and what works for me might not fit the bill for others, but definitely great to have multiple solutions to choose from in the market nowadays, when wishing to escape from Gas boilers! (biggest issue just being the cost of everything!)

 

[RedMod3]

The trade-off compared to AS/GS-heatpumps, is that rather than heating your entire wet-central heating system, you've now inherently got individual radiator control (app based in this instance, but other makes/model approaches available), less reliance on the pipes in your home (yay! no bleeding radiators ever again!) and no need for the initial air-source unit on the side of your home and/or digging up the garden and/or hooking up to your existing heating system!

snip

My main takeaway from all of the above is that its highly subjective, and what works for me might not fit the bill for others, but definitely great to have multiple solutions to choose from in the market nowadays, when wishing to escape from Gas boilers! (biggest issue just being the cost of everything!)

We have two air sourced heat pumps and 5 outlets and each outlet can be individually controlled. Only the lounge and main bedroom have an outlet, the other three are outside those rooms in halls. Rooms with no outlet like the kitchen, study, other bedrooms and dining room have extra free space as there are no heaters in them. We can have anything from one to five outlets operational at one time, and only in the coldest of winters or the hottest of summer hours do we ever have five outlets active at once. For most of the time perhaps two or three are on, though none for the past month. ASHPs are very cheap to run, and free in the summer.

However, now I'm considering a third Powerwall, and I think I can just about get away with another provided I limit the charging current to 15 Amps on each as 45 Amps is near enough 40 Amps.

 

[NikoV6]

When I built our system, I offset the size of our Solar Array with our potential battery storage capacity.

Realising the Grid is not the Enemy, especially when you can buy electricity so cheaply on Smart Meters and overnight Ev cheap-rate Tariffs.

So during Summer, our 7.2kWp Solar Array is enough. But in Winter it isn't enough.

But in Winter the battery storage takes over and cheap Grid Power becomes the primary winner.

So it works well... providing there is always cheap Grid Power available during the Winter months... my investment in battery storage is a good thing.

Would be interested to know if your DNO asked you to limit export please and if so which limitation device do you have?

 

[PITA]

Would be interested to know if your DNO asked you to limit export please and if so which limitation device do you have?

Yes no problem.

Our DNO limits our Export to 5 kW. Our Inverter is 5 kW and the Powerwalls do not export anything. So that's how it's done.

Our Powerwalls can import at 10 kW ... and that's DNO Approved and set up by Tesla within it's managed control system.

When it's all chirping along at night rates, we can regularly import at 25 to 30 kW via various battery storage (Powerwalls, Ev's, Home use). That's a benefit of 3 Phase cabling.

 

[NikoV6]

Yes no problem.

Our DNO limits our Export to 5 kW. Our Inverter is 5 kW and the Powerwalls do not export anything. So that's how it's done.

Our Powerwalls can import at 10 kW ... and that's DNO Approved and set up by Tesla within it's managed control system.

When it's all chirping along at night rates, we can regularly import at 25 to 30 kW via various battery storage (Powerwalls, Ev's, Home use). That's a benefit of 3 Phase cabling.

That's great thanks, we have a Solis 5G 8Kw inverter that can be throttled in software to 5kw. I wonder if the DNO would be OK with that. Failing that, I can CT clamp from inverter to mains as the last CT clamp before the grid to restrict inverter if it sees excess 5Kw from solar export