richard_scotland
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How best to expand an existing PV system?
richard_scotland replied to richard_scotland's topic in Photovoltaics (PV)
I will get in touch my DNO and see what they say. -
How best to expand an existing PV system?
richard_scotland replied to richard_scotland's topic in Photovoltaics (PV)
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How best to expand an existing PV system?
richard_scotland replied to richard_scotland's topic in Photovoltaics (PV)
thanks all for the responses and @frankmcs65 for the interesting ideas. Wondering about an alternative approach. The electric pole which is 5 m away from the house has 3 phases to it and a transformer on it. Our single phase supply is limited to 60A (due to size of cable apparently) and the cable goes under the slab to the middle of the house (the house was renovated in the early 90s). The fact we have a 12 kW heat pump, a car charger, induction hob + oven and everything else all on this 60A supply already makes me a bit nervous. We will likely go from one to two EV cars within a year or so, so the charger will get used several nights per week. Is there any merit in seeing how much it might be to have 3 phase installed to a new external meter box? as the pole is so close you hope the cost might not be too terrible... This might mean any new meter works as a smart meter, as its no longer surrounded by thick solid walls, allowing us to access TOU tariffs. From there we could connect up to the existing consumer boards internally? It used to be two cottages, so there are already two consumer boards, they could have a phase each and then the EV charger could be on its own phase? And doing this I would automatically get all the the extra PV export capacity I could want or use. An additional factor is that its reasonably likely we would want to build an accommodation annex in our garden at some point in the next few years - one of our children is disabled and has complex needs so ideally we will like to have additional accommodation for carers or helpers on site. That would be an additional load on our electric supply (heating, hot water, some basic cooking facilities etc) - so this might be another aspect pushing me towards looking into 3PH Obviously how sensible this is depends on how much the 3PH upgrade might be and if any of the above plan actually makes sense! -
How best to expand an existing PV system?
richard_scotland replied to richard_scotland's topic in Photovoltaics (PV)
i will have a look at this. We have an 11Kv line with a transformer on within 10 m of the house and that line only supplies 4 houses, I don't know if this is a sign there is likely to be extra capacity in the system? I guess the other option is to just get a few more panels and run them on the existing inverter. -
How best to expand an existing PV system?
richard_scotland replied to richard_scotland's topic in Photovoltaics (PV)
That sounds like a good idea - are they happy for you to chat to them to see whats possible? Yes thats true, but I guess it would only be for a few months of the year? I wouldn't be adverse to getting batteries, but I think the economics of them is poor when you can't charge them cheaply in winter. -
How best to expand an existing PV system?
richard_scotland replied to richard_scotland's topic in Photovoltaics (PV)
ASHP runs with radiators. I thought E7 was being phased out? -
Context We live in one of the sunnier parts of Scotland (east fife). Our overall electric use is high: We have ASHP (uses about 7000 kwh a year for heating and DHW - its an old cottage), 1 electric car (possible we may get another one within 2 years), family of 5 so relatively high overall other domestic usage (washing machine, cooking etc), totals around 14-15000 kwh a year? Zappi car charger. 3.6 kw Grid connected system (Solis 3.6 hybrid invertor), connected to 4 kw of Viridian in-roof solar panels, about 2.5 years old now. Invertor is located in the loft, with access through a standard loft hatch. No batteries. System generates about 3800 kwh a year, we use about 2700 kwh of that generation. We have a smart meter but it does not get signal (located in middle of house), so presently cannot access TOU tariffs, so everything is on standard rates and as much as I’d love to change that, we might be stuck with a non-functioning smart meter. Roof is directly south facing about 45 deg slope, easy access as its single story, mostly unshaded apart from in the depths of winter when it gets a bit of shade from tree branches. Room for around 5 or maybe 6 kw more panels on the roof, all on the same orientation. What’s the best strategy for expanding this system? My gut feeling is better to get more generation than batteries, as the most batteries could save is ~ 1000 kwh a year without TOU tariffs. Whereas we would surely be able to use more extra generation than that. Do we replace our relatively new invertor with a bigger one (e.g. 6 kw connected to 8kw of panels), or simply add another 3.6 kw invertor? Any ideas welcome.
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If its fixed then the flow temperature probably too low to keep your house wam for when its cold as it has been this last week - much better (and cheaper) to have it change flow temperature with the weather. This is something easy to set up yourself using the Daikin menu. I can look later at how you do this. We went to town with large radiators (quite a few K3), but we still needed 43 flow temperature this past week, you might need higher still if your radiators are fairly normal sized. Our design temperature was 55 degree flow at -3 outside (do you have this information anywhere?), but in practice we can run it cooler than that and be fine. This suggests to me that the unit is probably powerful enough. As I said ours is 12 kw and is not operating at max output and keeping our 200m2 single story cottage, half of which has no insulation on the walls, to 20deg. Our unit is mostly very quiet and never makes a noise like you describe, so I wonder if something is not correct here. Also, ours does occasionally 'whoosh' as part of a defrost cycle, but we never have to top up pressure and bleed radiators after this - the fact you have to top up the pressure frequently also suggests something is not quite correct with the pipework or system. when its not heating and its below a certain temperature outside ours does cycle the water in the system every 20 mins or so to prevent freezing - does yours do this? 100kw a day also suggests it is using the backup heater a lot. our 12 kw unit has only been using 55-60kwh a day (it sometimes uses the backup heater for a few minutes at the start of a cycle but they soon switch off). When its milder we are using 20-30kwh a day. I would persist in trying to get the installer back to look at the system as it doesn't sound like its working as it should do.
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Hi Tog I have the same model of heatpump and it is working OK to heat our 200m2 house (a not particularly well insulated old cottage) to 20 deg, and is using about 55 kwh a day at the moment to do that (producing 160 kwh of heat). We also upgraded our radiators and pipework. 1. what size in kw is your heat pump? we have the 12kw model which seems to be plenty big enough for us and works out at 60W per sq m 2. does it usually reach the 39 degree set point when its not so cold? 3. Our flow temperature is 43-44 degrees at the moment (-5 this morning), so I suspect 39 would be too low anyway at these temperatures, unless your house is very well insulated. Can you try turning the flow temperature up and see if the room temperatures improve? are the radiators warm at all to the touch? are you running weather compensation (flow temperatures vary with outside temperatures) or fixed? 4. we run our system with only a 1 degree setback at night - if yours is set to turn off overnight it might be that room temperatures have dropped too low and its struggling warm things up? You could use the Daikin menu system to go to Information>Sensors On ours this shows you more information about the actual flow temperature and also the flow rate etc which may be helpful. I think there is also a malfunction log in that menu which might be worth a look at.
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IWI or fully fill cavity (or both)
richard_scotland replied to richard_scotland's topic in Heat Insulation
thanks. Would the internal part of the gable wall in the loft count as a thermal bridge, if we didn't do IWI? in which case might it be worth putting a little bit of insulation up on the wall in the loft? -
IWI or fully fill cavity (or both)
richard_scotland replied to richard_scotland's topic in Heat Insulation
bumping in case anyone has ideas on whether it would be worth doing IWI to help with the thermal bridge at the corner, or even if I just did a small section of the wall in IWI (we would like to put a fitted wardrobe here) -
IWI or fully fill cavity (or both)
richard_scotland replied to richard_scotland's topic in Heat Insulation
Thanks. There is a junction where the cavity wall meets the old sandstone corner of the house. Would IWI be worth doing to help with this thermal bridge and potential cold corner? Or something else? -
IWI or fully fill cavity (or both)
richard_scotland replied to richard_scotland's topic in Heat Insulation
My only concern about beads is that the cable for the car charger crosses the cavity - its an outside rated cable so perhaps thats provides more protection from plasticiser migration? if not, I could try and wrap it with some sort of barrier tape (foil tape?) where it crosses the cavity. -
IWI or fully fill cavity (or both)
richard_scotland replied to richard_scotland's topic in Heat Insulation
Thanks, that makes sense. I guess the next question is, if I also add IWI (as the room is having work done anyway for the wetroom), how much should I add? EWI might be trick as there are no overhanging eaves -
Hi BuildHub, I've gained a lot of knowledge reading this forum but I have a question about how best to proceed with an upcoming installation of a wetroom into an existing bedroom - whether to add IWI to a partially filled cavity wall, or fully fill the cavity wall Current build early-2000s pitched roof single story extension wrapped around the end of 19th century sandstone single story cottage 3 bedrooms with external partial fill cavity walls external wall length (area in brackets) bedroom 1 - 10 m (2 windows) (23 m2) bedroom 2 - 5.4 m (1 window) (12.4 m2) bedroom 3 - 3.5 m (1 window) (8 m2) current u-value estimated at 0.54 wall construction (from some old plans we found) is plasterboard, 25 mm cavity, 100 mm concrete blocks, 35 mm insulation board (from what i can see looks like PIR), 50 mm cavity, 100 mm concrete block + cement render. We need to subdivide bedroom 1 to create a disabled access wetroom for one of our children (so there will be a fair amount of disruption to this room regardless). Given this work is taking place anyway, I am contemplating whether now is the point to add internal wall insulation. We are rural and near the fife coast fully exposed to the north sea on the east (just open fields between us and the sea), but somewhat sheltered to the west by trees. These rooms are on the west and north side of the house. Overall its a windy location, but not especially cold (-5 is the coldest we have had) These are the options I can think of, would be great to hear the collective wisdom from the forum members. Loft is already topped up to 300 mm. 1. Fully fill the cavity wall e.g. with EPS beads (all 3 rooms) pros -less disruption (and cost?) - more of the house improved at an earlier point cons - u-value still not great - worry about creating damp issues where none exist? - will I be able to find an installed happy to install a partial fill wall? 2. Internal insulation wood board 60 mm (just room 1 initially) an architect involved at an earlier stage proposed this option (to help with managing moisture + thermal mass perhaps) but I am not sure what the benefit is of this approach on what is essentially a modern concrete wall? Seems a lot of disruption for modest improvement in u-value? 3. Internal insulation PIR board (just room 1 initially) - loss of thermal mass? Options 2 and 3 would only be in room 1 initially. We would hope to also do room 2 and 3 at some point but we have 3 small kids so its possible it may not happen for a few years... and it will involve loss of space in what are already quite modest rooms. Any thoughts welcome thanks