News Alert

Wondering how to further reduce your energy bills? Have a look at the HOBBS report for a few ideas.
Showing posts with label PV panels. Show all posts
Showing posts with label PV panels. Show all posts

Wednesday, March 25, 2015

Open Homes April 2015 - Home no. 11 (Burnside House)

The eleventh home taking part in this year's spring time Open Homes event is on Burnside Road in West Bridgford.


This semi-detached house built in 1939 has been improved step by step over the last 7 years, and further work is planned.
Eco-features on display include:
  • Solar PV and solar hot water (2008-9)
  • Timber triple glazing (2014)
  • External wall insulation with government grant (2015)

For anyone considering External Wall Insulation, and interested to know more about the government's Green Deal Home Improvement Fund grant scheme that helps home owners with the cost of installation, this home and the one on Musters Road are very relevant.

This home is open on Saturday 25th April at 3.30pm

To book your free place, click here

(https://www.eventbrite.co.uk/e/twb-open-homes-2015-burnside-house-tickets-16324249269)

Tuesday, March 24, 2015

Open Homes April 2015 - Home no. 10 (Peveril Solar House)

The tenth home taking part in this year's spring time Open Homes event is on Peveril Drive in West Bridgford.



Peveril Solar House is a 2000's detached house. It is fairly standard in its original construction, but is far from ordinary in the renewable technologies employed. It is the UK's first entirely solar heated house, using a combination of power generation and underground thermal storage. 

Eco-features on display include:
  • Ground source heat pump drawing energy from vertical borehole
  • 6 sqm of innovative self-built sunboxes burying thermal energy 16 storeys underground
  • PV panel array producing more electrical energy than the annual heating requirement
  • Passive house style extension in SIPS panel construction
  • New - innovative composting and vertical farming systems
  • Solar dehydrator (will be on show before it gets moved to an organic farm)
  • Electrical car charging point
The home owner has developed the sun boxes as a research, design and build project, and monitored their impact, and has lectured about it, home and abroad. This is a fantastic opportunity to learn more about what renewables can achieve.
Other features that may be of interest is the disability adaptation of the house - sliding doors, wheel chair accessible bathroom, disable designed kitchen, platform elevator. 

This home is open on Saturday 3rd May at 11am

To book your free place, click here.

Monday, March 23, 2015

Open Homes April 2015 - Home no. 8 (Holwell House)

The eighth home taking part in this year's spring time Open Homes event is a 1940's end terrace in Holwell near Melton Mowbray.

This home has had to be withdrawn

There are others with some similar features such as 

Greenstone in East Leake.

So far, the owners have installed:
- low energy lighting
- PV panels on the roof linked to a system that diverts spare electricity from the roof to heat water.

They installed the PV panels in December 2014 so know how the system will run through the winter (the worst months for PV) and are no doubt hoping for a sunny summer!







Open Homes April 2015 - Home no. 5 (Harrow Road)

The fifth home taking part in this year's spring time Open Homes event is a 1950's detached house in West Bridgford.


  

It was extended and refurbished using the Passive House refurb standard (EnerPHit) as a guide. The works include: 


External wall insulation with render and some brick slips
Super-insulated loft conversion (insulation above and between rafters)
300mm insulation between ground floor slab
Triple glazed doors and windows, quad glazed roof light
Air tightness just over 1 ACH (extremely draught-proofed)
Whole house MVHR (mechanical ventilation with heat recovery)
Replaced all light bulbs with CFL or LED bulbs

Installed 3.2 kw solar PV system
Low water use features


This home is open on 11am and 3.30pm Sunday 26th April and at 3pm on Sunday 3rd May
To book your free place, click here.

(https://www.eventbrite.co.uk/e/twb-open-homes-2015-harrow-house-tickets-16286678895) 

Thursday, March 05, 2015

Open Homes April 2015 - Home no. 4 (Lady Bay)

The fourth home taking part in this year's spring time Open Homes event is a 1930's semi-detached house in West Bridgford.



In 2014 it was extended and refurbished. The works include:

New gas boiler and controls
New double glazed windows and doors
Additional loft insulation (including loft hatch)
Draught-proofing
Through-the-wall fan with heat recovery installed in the bathroom
Internal insulation (front elevation)
External insulation (back and side elevations)
Single storey extension (cavity wall construction to building regulations)
Solar PV panels fitted to south and east facing roof

This home is open on Saturday 25th April (2pm and 3.30pm) and Sunday 26th April (11am, 12.30pm, 2.30pm and 4pm).

To book your free place, click here.

(https://www.eventbrite.co.uk/e/twb-open-homes-2015-lady-bay-house-tickets-16036048252)






Wednesday, March 04, 2015

Open Homes April 2015 - Home no. 3 (Greenstone)

Our third home on the list was probably the first zero carbon barn conversion in the UK.

The barn, built in 1860, was converted in 2008 and now generates more energy than it consumes.



As you might expect, this was achieved with a highly efficient building fabric and a range of renewable technologies which not only serve the home but also help to run the electric car.

Super Insulation (25w/m2)
Air tight (2.3m3/m2@50P)
Whole house ventilation with heat recovery
Triple glazed
Underfloor heating
Ground sourced heat pump with bore hole heat collection for space heating and hot water
Biomass pellet stove for backup/occasional room heating
Solar thermal
Solar PV roof and ground mounted
Solar battery storage
Optimersion (using surplus solar electricity to generate hot water)
High use of thermal mass to reduce heating required and control summer overheating
Rain water recycling
Electric car charging

Detailed energy monitoring

For anyone wanting highly technical information about various renewable technologies, home owner David Hill will be able to answer a wide range of questions.

Open on Saturday 25th April at 10am and Sunday 26th April at 2pm.

To book your free visit, click here.

(https://www.eventbrite.co.uk/e/twb-open-homes-2015-greenstone-tickets-16024926988 )

David is also MD of Carbon Legacy Ltd., a local company which installs renewable technologies, and also one of the sponsors of this event.













Tuesday, April 22, 2014

Open Homes May 2014 - open for bookings!

Here are the links to each home on the booking system (with further details on these and other homes across the East Midlands in the blog posts below).

For last minute bookings (on the day, or the evening before), text or call 07962 453037 with the house name, date and time for the visit you wish to book. We will get back to you with the details and confirm whether there is space still available.

Book here for Wollaton Road Refurb in Beeston - in mid refurb! (17 May: 2pm)

Book here for Charnock Avenue Refurb in Nottingham - also in mid-refurb! (18 May: 2pm)

Book here for Elm Avenue in Beeston - the new addition to our booking system (17 & 18 May:  hourly tours from 2.30pm both days)

If you have any questions or any difficulty booking a visit, just email wbecohouses@gmail.com or phone 07962 453037 and we'll get back to you.

All these homes and others can be found on the Green Open Homes website - just put in your postcode to find a low energy home that is local to you.

Homes which have already opened are listed below. If you missed visiting one of these, there may be opportunities for "ad hoc" visits in the next month or so. Just email wbecohouses@gmail.com with your enquiry as we now have a waiting list for several homes.

* Worwood Drive (left hand branch)  on 10th May between 11am & 3pm and make your way to the house with the gazebo and the green balloons in the front garden.

Greenstone - a zero carbon barn conversion in East Leake (10 May: 10am and 2pm)

 Harrow House (towards EnerPHit) - a nearly Passive House refurb (10 & 11 May: 2pm both days)

The Green Man House - an ultra-low energy new build near Market Bosworth (10 May: 10am and 2pm)

* Peveril House - solar power & ground source heat pump (11 May: 12 noon and 4pm)


Tuesday, April 08, 2014

Open Homes May 2014 - House number 5 of 7

Our 5th Open Home this year (on Wollaton Road in Beeston) is "mid refurb", so it really is a great opportunity to see the nuts and bolts of what's being done now while you can still see the insulation and other elements that will eventually be hidden.

To book your free place for the 2pm tour on the 17th May 2014, click here.

Mid-refurb!
An extraordinary self-build project to significantly extend and energy efficiently refurbish a mid Victorian semi-detached villa.  The owner is carrying out most of the work himself including some fairly serious structural challenges and braving all weather.
Features:
Single storey rear extension shell complete including green roof, Passivhaus style timber frame and oak cladding.
Large side extension substantially underway including a full size basement built next to the existing house which alone took a year owning to needing to underpin sections, build retaining walls and beam others.  Superstructure of extension 3 storeys above basement in Porotherm clay interlocking lattice blocks 365 mm thick (complete) with 100 mm EWI over (planned).
Green Building Store windows throughout, different ranges.  
TJI engineered floor joists.
PV on the workshop.
Solar thermal planned on large dormer roof.
Wood pellet boiler planned.
Double height conservatory planned.

Roof should be complete and windows installed ready for EWI.

Open Homes May 2014 - House number 4 of 7

On Peveril Drive, West Bridgford, just up the hill from house number 3 (see previous post) is another seriously low energy home - achieved in a very different way.

To book your free place for the 12 noon or 4pm tour on the 11th May 2014, click here.


This house was built with extra cavity wall insulation and has subsequently been fitted with solar hot water panels, solar PV panels, a ground source heat pump linked to 2 "sun-boxes" and more recently still a PVT system.

The owner is a technical expert on this system, using it for cutting edge research into the levels of efficiency that can be achieved with a ground source heat pump.



Open Homes May 2014 - House number 3 of 7

Our third open home (Harrow House / Towards EnerPHit) is an ultra-low energy refurbishment which was designed to meet the EnerPHit (Passive House refurbishment) standard.

To book your free visit to this West Bridgford home, click hereNumbers are limited so that you get the best from the visit, with time to put your questions to the home owner during / after the tour.



Although the air tightness figure of 1.08 ACH narrowly missed the target of 1 ACH required for certification, the performance of the house is definitely in line with the EnerPHit standard.

The house provides comfort and excellent air quality in hot and cold weather. Gas use for the last year was a tiny 4800 kWh (heating plus hot water) and electricity bought in from the grid came to 1500 kWh.

In other words, gas costs around £200 per year (plus a standing charge), and electiricity costs almost exactly the same. Altogether, this means that we earn more for the electricity generated by PV panels on the roof than we pay for gas and electricity.

The secret is the Passive House methodology - insulation, air tightness and a whole house ventilation system with heat recovery. The thermal mass prevents overheating in summer and keeps indoor temperatures steady all year round.



Friday, April 04, 2014

Open Homes May 2014 - House number 2 of 7

A little closer to home, in East Leake, is our second open home, Greenstone.


It's a zero carbon barn conversion with a long list of features. And since this home last opened to the public, there have been a few additions to maximise use of the elecctricity generated. If you have not been before, it is well worth a visit!

To book your free place for the 10am or 2pm tour on the 10th May 2014, click here.

·         Super insulated 9” solid brick walls (oldest barn built in 1860)
·         Factory made Insulated roof panels (SIPS)
·         Super insulated floor slab with wet under floor heating (ground and first floor)
·         Extensive use of thermal mass in floors, internal walls and ceiling
·         Itho Whole house ventilation with heat recovery 90% efficiency
·         Triple glazed timber windows with aluminium outer skin (Rationel)
·         Draft lobby with highly insulated doors (Rationel)
·         Air tight construction with measured value of 2.3m3/m2@50Pa pressure
·         Thermal store feed by oversized Solar Hot water panels and heat pump for space heating and domestic hot water
·         10kw roof mounted Solar PV system
·         20kw ground mounted Solar PV system
·         Powerrouter 5kw battery storage system providing solar produced electricity at night and back up electricity in the event of a power cut
·         Two intelligent immersion switches using spare solar generated electricity to heat hot water in 400 and 300L thermal stores
·         Ground sourced heat Pump (GHP) providing space heating and some of the domestic hot water
·         Electric car powered from the solar PV panels
·         Experimental Solar PVT panels providing Earth charging energy from solar panels to improve the efficiency of the GSHP
·         Recently installed Web based energy monitoring equipment measuring electrical use, solar power generated, appliance consumption, heat generation
·         Rain water recycling from underground tank to provide water for toilet flushing and garden irrigation
·         Presence and daylight sensor light control in common areas of the house
·         100% low energy lighting and low energy appliances
·         Reserve wood pellet 5kw stove in case of power failure

Interesting facts/results:
·         It works!
·         It has met its target energy consumption with 3 years’ worth of all power consumption (electricity) 10,500kwh/year
·         The house is now a net exporter of  Solar generated electricity providing a very useful additional income stream
·         It  also provides free electricity to charge 2 or more electric cars the first of which is doing really well (Volt)

·         The family loves it because it is comfortable and pleasant to live in all year round

Tuesday, March 11, 2014

Open Eco Homes event in May 2014

If you are interested in seeing inspiring examples of energy efficient homes, there are various events coming up across the UK in May.

Here in the East Midlands, we're joining in the fun as usual. There are plenty to choose from in Nottinghamsire and Derbyshire (here) and in Loughborough

Transition West Bridgford's Eco House Group has a number of interesting homes lined up and a few more to be confirmed. If you would like to receive an email invite once all our homes and opening dates and times are confirmed, just email wbecohouses@gmail.com to join the mailing list. Or check this website as every home will be featured here over the next 4 weeks and booking details will be provided.




Thursday, January 10, 2013

Arguments for and against PVT


9 Jan 2013: DNC writes: There's an interesting article on the Solar Blogger website by Stuart Elmes. It's about PVT (Photo-Voltaic-Thermal) panels, and he has a more technical PDF linked to it.

PVT panels are, in essence, a PV panel with a mesh of liquid cooling tubes behind the PV surface. For higher PV capture, the panel is uncovered, but for a higher thermal capture, the panel has a glass cover over it and insulation behind.

   I am a great believer in PVT, but the only properly productive application for it that I can see is when it is associated with low-grade thermal storage and heat pump.
   It could also good for those who have a limited area of roof, and haven't enough space. If you have enough roof surface to play with, the best place for PV might not be the best place for thermal. Ideally, a house needs 28-30 square metres of PV to attain the 4 kW that is recommended for the Feed-in-Tariff in the UK - a smooth, unobstructed and unshaded area facing south is the best. PV arrays normally have an air space under them and they work best on sunny days with a cooling northerly breeze that can get under the panels.
   For solar thermal, the size can vary from 1sqm to 4sqm. Above that, it gets a bit silly unless you are addicted to hot showers all summer. So Solar thermal can often work well in smaller locations on hipped roofs, or large dormers, providing you can get a south aspect. Another criterion for best place might be closer to the optimum positions of a tank and the plumbing.
   The idea of PVT is that you get a larger area for thermal, and the PV element is cooled by the liquid passing under it.

   The paradox is this: for you to get useful heat to a water tank, you want the panel to run very hot, but for the PV panel to run well you want it to run very cool. Stuart's article explains the paradox well.


   So for a solar thermal water tank you want the circuit to run at 50-70ºC, and when the tank reached 60ºC, the circulation would stop. If you ran PV at these temperatures it would be unworkable. If you want PV to be optimised, the purpose of the liquid has to be to cool the PV, so it should be circulating at 15-20ºC. A normally air cooled PV panel reaches 40-50ºC surface temperatures on a hot summer's day, but the PV cells run better is the wind is blowing.
   If the water tank reaches optimum temperature and turns off the pump, the sun will make the PV even hotter, and as there would be insulation behind the PVT panel, there's nothing to stop the liquid temperature getting dangerously high. Stuart's article refers to the risk of temperatures as high as 220ºC. (I am informed by Newform that this might be a mistake, as Powervolt panels permitted to stagnate seriously haven't gone higher than 100ºC, although the glass topped Powertherms might get hotter.)

Therefore, for thermal storage for a heat pump, the panels running at 15-20ºC would be warming an infinitely large tank size, the earth, whose base temperature would be 10-12ºC, so there will always be a benefit. There is no risk of any of the system reaching stasis and turning off because earth has a vast thermal capacity in relation to the size of the panel array or the size of the building above it.
    Having a larger surface area than normal solar thermal panels (28sqm instead of just 2 or 4sqm) the solar thermal gain for the store - large volume of low grade thermal energy is going to be very good! One thing that my experiment has shown is that the ground does not get 'hotter', but the volume of earth that is warmed up to a moderately warm temperature gets larger.
    One thing about any of these systems, is that they must keep running. If the system circulates reliably everything is the right temperature. If a future owner of this house just turned the solar circulation off in summer, there would be problems if temperatures rise and there isn't sufficient capacity for expansion of the liquid.

Tuesday, August 21, 2012

Open house visits in September

Several local homes which have been built or refurbished to use less energy will be opening their doors during September to interested visitors. Visit and ask any questions you like.

Keep an eye on the website as additional houses and other details may be added in the next few days:

1st September
• 1950's ultra-low energy refurbishment (passivhaus) in Derby.
There will be a tour from 10.30am to noon and a later one from 1pm if numbers require a second tour.
(Child-friendly arrangements are possible here - just ask for details).

8th September
• Penney and Gil's 1890's house (now very low energy indeed) in West Bridgford
There will be a tour from 11.30am and 1.30pm,

Edwardian home in Carlton - book your visit on 8th or 9th September via the Superhomes website: (http://www.superhomes.org.uk/superhomes/nottingham-carlton-mayfield-road/)

15th September
• David Hill's zero carbon barn conversion in East Leake (superinsulated, renewable technologies and now an electric car)
There will be a tour from 2pm,

16th September (10 mins walk between these two)
1950's ultra-low energy refurbishment (passivhaus) in West Bridgford
• Website (http://www.eco-retrofit.blogspot.co.uk/)
There will be a tour from 2pm and a later one from 3.30pm,

2000's house with cutting edge renewable technologies in West Bridgford, and a ultra-insulated extension under construction
• Website  (http://chargingtheearth.blogspot.com)
There will be a tour from 2pm and a later one from 3.30pm.

Unless indicated otherwise, contact wbecohouses@gmail.com 
for more details or to book your place.

Wednesday, January 25, 2012

Low energy homes exhibition a success

On 21st January 2012, the exhibition of low energy homes attracted about 130 people interested in seeing the homes on show and listening to the talks. With stall-holders displaying a range of technologies from Rushcliffe Borough Council's light-bulb library to full scale home refurbishments and renewable technologies, there was a lot to see. To read about the stalls, talks and afternoon house tours in more detail, read the full write-up here.

A very big thank you must go to the exhibitors and a super team of Transition West Bridgford / Eco House Group volunteers who worked hard on the day to make it happen and to provide a warm welcome to the visitors.

This exhibition marks the final event in our "Eco Houses under Construction" series, but don't worry - there will be opportunities to see these homes and others in the future.

Thanks to our recent successful LEAF funding bid, there will be further house visits and a set of workshops due in March, so look out for our "Homes Behaving Badly" events. The idea is to make sure that these workshops are as relevant as possible to those who come along. Knowing that West Bridgford has more than its fair share of solid wall homes and large areas of cavity wall housing, different workshops will focus on different types of homes and the associated low, medium and high cost solutions to cut energy use.

As well as looking at all the feedback from the exhibition, we would like to know if you live in a cavity wall home or a solid wall home, and what issues and options you need to know about in more detail. A questionnaire is coming soon!


Monday, November 21, 2011

December PV scramble!

21 Nov 2011: DNC writes: I had an email from Good Energy today to say that they will have staff in the office on Saturday 10th (10-4pm) and Sunday 11th (12-6pm) in December to super-streamline OfGem registrations in time for the midnight deadline of Dec 11th. If you get your installation registered by then, you are on the 43pence tariff for the next 25 years! Some utility companies are telling people that they need 3 or 4 weeks to register, so don't take that nonsense from them - switch!
    I don't normally want to promote one company only, but if they can do this for the customers, it's a benefit for all. Also. I hope they can lose George Monbiot his £100 bet - he bet someone that renewable energy companies can't maintain their prices till  2014... but GE have already maintained their prices without an increase for 4 years - due to the fact that their 'Wholesale Fuel' price is zero - the Wind for their windfarm and the Sun for their customers who are home generators!
     This underlines the fundamental benefit of renewable technology - it trumps all the arguments of people who say that Wind farms or Solar or Hydro is not 'economic'. The fossil/nuclear generators are helped by the many visible and invisible subsidies and economies of scale that the fossil/nuclear systems get - but every other one of these is trumped by the fact that the renewables come free, but the nuclear fossils have a Wholesale fuel purchase price, with competition from others to obtain those fuels, with risks of war or hostilities cutting off the supply.

Monday, November 14, 2011

Eco Houses Under Construction - Event 5


On 12th November, a dozen people gathered to find out more about barn conversion in East Leake that will soon become zero carbon. David Hill (now Managing Director of Carbon Legacy Ltd.) turned the old dairy into a comfortable, highly insulated space. If you think that going low carbon is for the “hair shirt brigade”, think again – this is definitely luxury low carbon living!

Good air quality is provided by the MVHR system (mechanical ventilation with heat recovery), which draws stale air out of kitchens, bathrooms and the utility room, and sends warmed fresh air into the main living spaces. (This makes the utility room a great place to dry clothes simply because of the air flow.) The system was extremely quiet (well, I didn’t even notice it), although it could be heard in the utility room where the MVHR box was located.

 The house design ensures thermal comfort thanks to insulation, controlled ventilation rather than cold draughts, and plenty of “thermal mass”. Thermal mass is present in the form of stone floors and stone or brick walls – these absorb heat to keep the house cool on a hot day, and release the heat as the air cools in the evening.


Energy is provided in a variety of ways:
The forthcoming addition of more PV panels to create a 10kwp system, will equal the entire annual energy consumption of the house (10,000-10,500kWh per year). Furthermore, the imminent installation of an inverter with intelligent control system and batteries (called Power Router from Nedap in Holland. www.powerrouter.com) means that this house will continue to have an electricity supply even if the rest of the area suffers a power cut!

Solar hot water panels supply hot water during the summer months, and a ground source heat pump provides heat to the under-floor heating system. Recently, a pellet burning stove in the main living area has been installed in case of power failure or temperatures below -10 degrees C or when the main heating system has not been switched on.





Monday, October 10, 2011

Eco Houses Under Construction - Event 5

The 5th event in the series will take place on Saturday 12th November, 2-5pm.

This is a rare opportunity to visit the UK's first Zero Carbon Barn Conversion, just down the road in East Leake. The developer (and owner) of this home is David Hill, who previously developed the UK's first Code 6 new build Zero Carbon homes in Upton, Northampton. He is now director of Carbon Legacy Ltd.

Although not still "under construction", this house has the advantage of 3 years' energy data post completion, showing that the approach taken has worked.





(For anyone who attended the series of Eco House Seminars which we ran this time last year, you may remember that David presented a talk on low energy refurbishment, and also contributed to the seminar on renewable energy for homes.)

For more information or to book your place on this free event, email Tina on info@wbecohouses.co.uk

Here is David's summary of the house:


·         Super insulated 9” solid brick walls
·         Factory made Insulated roof panels (SIPS)
·         Super insulated floor slab with wet under floor heating (ground and first floor)
·         Extensive use of thermal mass in floors, internal walls and ceiling
·         Whole house ventilation with heat recovery 90% efficiency
·         Triple glazed timber windows with aluminium outer skin (Rationel)
·         Draft lobby with highly insulated doors (Rationel)
·         Air tight construction with measured value of 2.3m3/m2@50Pa pressure
·         Thermal store fed by oversized Solar Hot water panels and heat pump for space heating and domestic hot water

·         10kwp Solar PV system installed in December which should make us carbon neutral in energy use. Half of the system also feeds a new type of inverter (Nedap Powerrouter). This will do 5 important tasks: Send power to the house as it is required, when the house does not need the power divert it to a large battery store, in the evening when the house is calling for electricity turn the battery power into AC and send it to the house, during the day if the house does not need power and the batteries are fully charged then export power to the grid, should the Mains Grid supply fail then the unit will continue to feed converted power from the batteries into the house independently.

·         Ground sourced heat Pump (GSHP) providing space heating and some of the domestic hot water
·         Experimental Sunbox providing Earth charging energy from solar and ambient air to improve the efficiency of the GSHP
·         Rain water recycling from underground tank to provide water for toilet flushing and garden irrigation
·         Presence and daylight sensor light control in common areas of the house
·         100% low energy lighting and low energy appliances
·         Planning permission and foundation pad for a 10-15kw VAWT wind turbine for when I find one that works!
·         Reserve wood pellet 5kw stove in case of power failure

Interesting facts/results:
·         It works!
·         It has met its target energy consumption with 3 years’ worth of all power consumption (electricity) 10,500kwh/year
·         If we had the 10kw wind turbine (long story) or when we install the 10kw or bigger Solar PV installation then the house will generate as much or more power than it consumes.
·         It may also provide free electricity to charge 2 electric cars the first of which is due to arrive in 2012
·         The family loves it because it is comfortable and pleasant to live in all year round

Sunday, October 02, 2011

September Heatwave

2 Oct 2011: DNC writes: The heat wave at the end of September 2011 produced 3 successive PV-Maximum days in a row. As it is after the Equinox, these averaged 13.5 kWh only per day on my east facing 4KW array, but it is still nice to have them. The lower daily harvest is due to lower sun angles and short hours of daylight. It's distressing how quickly it gets dark in the early evenings!
    It says something about the summer we have had (a lot of cloudy bright conditions) that that last day that PV was close to a maximum was 14th June, and previous to that it was May 1st and 2nd!
     For those who installed in early 2011, the good news is that 2011 has so far been sunnier than 2010, July and September being notably better.
dnicholsoncole@gmail.com