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Tag: solar array

  • HPH276 : A case study of Hope View Passivhaus – with Tracey and Roman Iwanczuk

    HPH276 : A case study of Hope View Passivhaus – with Tracey and Roman Iwanczuk

    Tracey and Roman Iwanczuk explain how they managed to build a Passivhaus on a sloping site in an Area of Outstanding Natural Beauty.

    Interview with Tracey and Roman Iwanczuk

    Having lived in the US for 20 years and at the point where they were preparing to build a house there, Tracey and Roman made the decision to move back to the UK. Being unable to find a house or building plot that ticked all their boxes, they decided to embark on what initially seemed like a fairly improbable chance of getting planning permission to build a property on their six acre field overlooking the Malvern Hills Area of Outstanding Natural Beauty.

    It was a leap of faith

    Initial meetings with a planning consultant and a local architect offered little in the way of optimism for ever getting planning permission on the site. But they persevered and found another architect who offered a more encouraging 50/50 chance.

    Being a greenfield site they used the Paragraph 55 application process for a house of exceptional design and quality that could enhance the area. As Tracey explains, being a greenfield site isn’t always the best use of a piece of land, and their steeply sloping site wasn’t practical for agricultural use.

    “It was a matter of coming up with a way of saying let’s do something that is a benefit for our environment, our area, and maybe even the people who live around here that makes sense.”

    The scheme they came up with was to return three acres of the land to natural woodland by creating an orchard of local species trees.

    They also put in a flood prevention strategy for the neighbours below, who’s properties had experienced flooding from run-off from the field previously.

    The house nestles into the hillside

    The house was designed to have a minimal visual impact and be future-proof for any long term needs.

    The design came about from a series of 15ft² boxes joined together in a single-storey. The principle rooms are south facing and benefit from the floor to ceiling glazing to maximise the beautiful views, with the other rooms being at the rear.

    Despite the glazing, the temperature of the house remains relatively even. The rear wall is built into the hillside so has a lot of surface area that is removed from the equation.

    Being built into the hillside to a large extent determined what build system they could use. In order to get the required structural strength they used concrete, and felt less guilty with the knowledge that the orchard they were creating would be off-setting the carbon.

    A “long, skinny Passivhaus”

    Roman describes the shape of the house as providing its own unique challenges, of which air leakage was probably the biggest. The concrete block walls at the rear get no sunlight, whereas the pre-fabricated concrete plank roof gets a lot of light and a lot of heat. So with different thermal expansion rates between the roof and the walls they used a Passivhaus window tape as a barrier for the airflow and to provide enough flexibility to accommodate any thermal expansion.

    A ground source heat supply provides hot water

    Excavated soil was used to create a level area in front of the house where they could lay pipes for the ground source heat supply. They chose this over an air source system as it is such a peaceful location that they felt it would be less noisy.

    About 80% of the supply is used for hot water, with very little actually being needed for heating. Tracey points out that it does use a lot of energy to run a ground source heat pump and they really notice the difference in their electricity bills in the winter when they’re running it to heat the hot water.

    When it’s sunny they don’t need to use the ground source heat pump as they export excess solar power to an immersion tank for the hot water supply.

    There is a 30 panel solar array

    The array gives almost nine kilowatts of generation capability. There are two first generation Tesla Powerwalls which that feeds, that can store around 14 kilowatts. They don’t have the means of exporting power from the batteries, but what they can do is “time shift” the excess energy generated during a sunny day for it to be used to run the house at night.

    With advancements in technology, the battery system is one thing that Roman is considering changing. When they were installed the only batteries that were readily available were these kind that sit on the DC side of the system. They are almost directly connected to the solar panels, which means that the system is designed to completely switch off the electricity in the event of a power cut. This is because there could be a danger of feeding the power back onto the grid and electrocuting anyone working on it, but it does mean they can’t access any of the energy sitting in those batteries during that period.

    The more modern Tesla system works on the AC side. If there were to be a power cut it would isolate the house but still allow the batteries to generate AC voltage.

    “If there is a power outage, then your house effectively becomes an island of electricity and you can use whatever power is in the batteries.”

    To upgrade to this system will mean a bit of disruption in having to change the location for the batteries, but Roman thinks that it will be worth doing. There is also a second hand market for the Tesla batteries so they can be re-used by someone else.

    The plant room

    They have high praise for their team

    Tracey and Roman consider themselves to have been very lucky in how smoothly the project generally went. The only real issue they had was with the window supply, which has taken around three years to fully resolve, but they do say to the company’s credit they have stuck with it to get a resolution.

    Tracey praises their architect who had never done a Passivhaus before:

    “He was more than happy to park his architect ego, listen to the Passivhaus consultant and do the right thing to achieve a Passivhaus. He was happy to learn all of this stuff and take it on board.”

    They selected a contractor who had also worked with the architect before, and this helped with maintaining good working relationships between them all. Tracey also praises their integrity and says they were very respectful in how they communicated with her.

    Think about your window to wall seals!

    One area that could have challenged the successful outcome of the project, was the seals between the windows and walls. Despite their Passivhaus Consultant, Nick Grant, flagging up how important it was to get right, it had been forgotten about in amongst all the other decisions that had to be made. It wasn’t until a week and a half before people were due to do the render that they realised they hadn’t thought about the window to wall seals at all. It was pure luck that they were put in touch with someone who had some spare pieces from their own self build that they could use.

    “If that had not been done, it would be a nightmare right now. We’d be dealing with silicone, silicone in windows all the time, just doing all of that stuff that would make life miserable. I can’t say enough to anybody who’s looking at doing a self-build; think about that very, very early on because we only fixed it by accident. It was a very, very lucky accident.”

    Roman warns that when you have a window company dealing with the windows, and a builder dealing with the building envelope, things like how those windows will join with the building envelope can become overlooked.

    A HEPA filter would be a worthwhile investment

    The one oversight that Roman feels they made was the issue of airflow in the house. The MVHR draws in outside air but, being in a rural spot, this can include the smell of burning horse manure! The basic filters are there to get rid of particulate matter, but they don’t deal with smells. He recommends the inclusion of a HEPA filter, which he doesn’t think is something he can now retrofit because of lack of space. He considers the £500-£1,000 for a HEPA filter would be money well spent, even more so in an urban environment with emissions from exhausts.

    ASBP Healthy Buildings Conference and Expo 2020

    This is taking place in London on 27th February, and will be addressing the subject of healthy buildings in a climate emergency. Check out the website for the full programme and booking tickets online.

    Find out more

    Visit the website of Warren Benbow Architects

    Follow Nick Grant on Twitter

    Transcript

    Download a transcript of the interview with Roman and Tracey Iwanczuk.

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  • HPH206 : What solar PV panels should I get for my roof? – with Robert Flynn from Solarbarn

    HPH206 : What solar PV panels should I get for my roof? – with Robert Flynn from Solarbarn

    Robert Flynn from Solarbarn explains how to choose a solar array to suit your needs.

    Interview with Robert Flynn

    After spending 25 years in the IT industry, Robert had a change of career and set up Solarbarn. It was 2010 and at a time when the government introduced the feed-in tariff scheme which kick-started the whole industry.

    While we have spoken on the podcast before about solar PV, we haven’t discussed what is required for the installation process.  As we have been following Solarbarn’s installation at Buckinghamshire Passivhaus, our video case study in The Hub, we thought we would speak to Robert to give us an idea of what you’ll need to think about if you’re planning to install solar PVs.

     

    Higher watt panels are only really needed on a small roof

    How many panels you need will depend on your roof area, how much energy you want to produce, and how much you are prepared to pay.

    According to Robert, you can’t really have too big a system. A large system may well produce more electricity than you need at a particular time, ie during the summer, but any surplus isn’t wasted as it is simply fed back into the distribution network to be used by others.

    A standard solar panel is now 300 watts, but you can get 360 watt panels if you want to pay extra for a more efficient product. Robert suggests if you have a large roof you don’t need to pay for the more expensive panels, as you have the space to install more of the cheaper, 300 watt panels. He says the pricier 360 watt panels are really only necessary where you have a small roof and typical sized panels aren’t going to give you the power you need.

     

    Roof pitch should be considered along with orientation

    A south facing array will produce more killowatt hours in a year than an array pointing east or west, or south-east or south-west.

    The shallower the pitch, the less of an issue orientation is. For example, with a shallow, 20 degree pitch, the panels are closer to pointing up in the air than at the horizon. A 45 degree pitch will make a difference as it is pointing more to the horizon. So a 45 degree pitch east/west will produce probably 25% less than the same array on a south facing roof.

    In terms of consumption however, there can be benefits of going east/west. An east facing array will produce a little more in the morning, and a west facing array will produce a bit more in the afternoon than a south facing array. A south facing array will give you a bigger peak at midday, with perhaps less in the morning and afternoon.

     

    Installations on new-builds are built “in-roof”

    As Buckinghamshire Passivhaus is a new-build they have been able to do an in-roof installation. The solar panels are part of the roof so it ends up being tidier than a retrofit would be. It also means you save on the cost of roof tiles as these are not required under the panels.

    The roof is built, felted and battened. At that stage Solarbarn would lay interlocking plastic flashing frames onto the battens which will ultimately hold the panels in place. The roofers return to tile the rest of the roof up to the flashing frames and making it watertight. The solar panels themselves aren’t put in place until the roofers have finished their work, to make sure they are protected and aren’t going to get damaged.

    At this installation the clients are using a power optimiser solution. A power optimiser on each solar panel means that the panels can work independently of each other, so if one is shaded for example, it wouldn’t affect the output on any of the others, which on a traditional wired system can be an issue.

    The distribution network operators need to be notified of systems up to 4 kilowatts after they have been installed. Anything over 4 kilowatts, as in the case of Buckinghamshire Passivhaus (7kW), needs to have their approval in advance as they need to be sure that the infrastructure is capable of taking the load when power is being injected back into the network.

    The solar array is first tested on a sunny day to make sure there is enough power going into all the panels and optimisers. The inverter is switched on and is paired with the optimisers at a safe 1 volt DC. When it is fully up and running it will be up to around 400 volts DC.

    The inverters get hot when producing a lot of power and eventually they will need replacing. They should last at least 5 years, and are usually guaranteed to last between 5 and 10 years. The inverter on the Buckinghamshire Passivhaus project is guaranteed for 12 years.

    Buckinghamshire Passivhaus

     

    Excess power can be diverted to an immersion heater

    A lot of customers of PV systems now have an immersion heater diverter, because in a lot of cases PV systems will produce a lot of energy when you don’t need it. This channels any surplus power that would otherwise be exported, into your immersion heater.

    Robert doesn’t feel that the economics of using batteries are quite right just yet, as they are expensive, don’t store quite enough and don’t last long enough. He does see a tipping point where improvement in battery technology plus escalating electricity prices will make batteries in solar PV installations a more feasible option.

    They have future-proofed Buckinghamshire Passivhaus by laying cables ready for batteries and technology to measure how much of the power they use and how much they export. By being able to measure their actual consumption they will be better placed when it comes to buying a battery array that is right for their needs.

     

    Ground solar arrays can be an option if space permits

    A solar panel pointing to the sun produces as much electricity on a frame in the ground as it does on the roof of a house, so space permitting, a ground installation might be an option. To make it worthwhile there usually needs to be a meaningful sized array, and for that size you will need to obtain planning consent. They need to be kept secure from children and animals endangering themselves, and also from theft. Typically, the ground arrays Solarbarn install for clients tend to be for large country houses that have swimming pools and huge oil consumption.

     

    Benefits are now more about self-consumption savings, rather than feed-in tariff payments

    People are always keen to know how soon the system will start paying back. Previously the benefits to be had were in the feed-in tariff payments, but nowadays the benefits are more to do with self-consumption savings, ie “producing lots of electricity, using it yourself and therefore not having to buy it from the grid.”

    “Generally, the people that were motivated purely on return on investment and how quickly they could get their money back are not those that install solar these days. The people that install solar these days are the people that want to do it because they know it’s the right thing to do. ”

    The benefits of installing a solar PV system at the time of building a house are that it is zero VAT (because it is a new build) and there are no scaffolding costs because the scaffolding is usually there already. Most of the work they do on new builds is now just considered an extra cost at the time of construction that will provide a huge ongoing benefit thereafter.

     

    The Hub

    For in depth videos following the progress of Buckinghamshire Passivhaus and other case studies you can join our members only area of The Hub. As well as step-by-step courses, you will also be able to join in with our monthly progress calls where members can share news of their self build projects and get advice from guest experts.

     

    Find out more

    Visit the website of Solarbarn

    Follow Solarbarn on Twitter

     

    Transcript

    Download a transcript of the interview with Robert Flynn.

    Please connect with me