The solarventi is enjoying a rest. What a grey week it has been. Nevermind.
We have the answer to warm but dull days.
And it is an air-to-air heat pump, also know as an inverter, also known as an aircon unit.
We are pleased to announce that the Solarventi on the south side of the house has been balanced by an aircon unit on the northside.
The aircon unit uses refrigerant and a pump to extract heat and pass the heat energy via the refrigerant either into or out of the house.
Hence it is known as an inverter. It will heat or cool the house as your need changes. This model, mitsubishi heavy industry SRK20ZIX-S is the second most efficient on the market at the moment. (The hitachi model slightly more efficient is almost twice the price, so no economy there, bit of a posing stainless steel job I understand). This model has a COP of 5.5. i.e. generates 5.5Kw heat for every 1 Kw of electric used.
Installed by http://www.orionairsales.co.uk from bedfordshire.
Helpful bunch, 15% VAT on the web site is 5% if they install for you, as per current Govt VAT concession.
I recommend them. But please make sure they arrive with the exact model you ordered. It seems nobody including me noticed the switch to a far less efficient model by their supplier. Nearly collapsed with shock when I double checked.
As it is, 3 days in, and the unit is warming more rooms than I could have imagined possible, with outside temps of between 10 and 18 degrees c it's perfect. And puts off the day of the gas central heating starting up. Fantastic.
So air source heat pump downstairs, solarventi upstairs. This is good news for our fuel bills this autumn. I look forward to seeing how it works out in the coldest winter days, when the heat pump is less efficient.
Thursday, 17 September 2009
Saturday, 22 August 2009
Solar panel salespeople
Solarventi sales process was so straight forward. The gentlemen were able to confirm over the phone from photos and internet bird's eye photos of our house.
No site visit was necessary before arrival for installation. Saves precious resources. Saves me time.
Compare this with SolarEssence from Thetford.
They cold call and on agreement send round a "marketing executive" salesperson who want to visit and take 2 hours of your time without adding to your day.
Retails at 12,000 he says, when I dismissed his price of over 6,000 out of hand.
The amount of solar radiation in Dec. is less that 1 KWh per m2 per day on average in the UK. Therefore the idea that you can "heat your house" or provide more than 70% of your hot water requirements annually without some large m2 of vacuum solar tubes and some very efficient heat storage is just fantasy.
Even if gas rose to 10 times it current price their offering would not have saved me over 6,000 in it's lifetime. And there are much more economic, efficient, ways of being "green".
e.g. Biogas, or wood fuels, or electric efficient heat pumps.
The solarventi is an exception in my view. It does more than just add hot air. It has freshened our bathroom upstairs less over the summer months with the sun so high. But it has been more active as August has passed and the sun's angle of incidence on the panel has increased. Remember the panel is close to vertical.
The dehumidifying action increases too.
I was able to switch off the central heating earlier this year than previous years and I anticipate the central heating will come on later this autumn. I am conscious that the solarventi is part of the reason for this. It's 17 degrees outside this morning but bright sunshine. The central heating might have kicked-in over night (but it's not switched on). But the solarventi was purring away with the early morning sun.
We visited a friend last week, it's mid-August, who had windows on trickle vent/closed upstairs and the mugginess in the bathroom was a reminder where we would have been without the solarventi.
No site visit was necessary before arrival for installation. Saves precious resources. Saves me time.
Compare this with SolarEssence from Thetford.
They cold call and on agreement send round a "marketing executive" salesperson who want to visit and take 2 hours of your time without adding to your day.
Retails at 12,000 he says, when I dismissed his price of over 6,000 out of hand.
The amount of solar radiation in Dec. is less that 1 KWh per m2 per day on average in the UK. Therefore the idea that you can "heat your house" or provide more than 70% of your hot water requirements annually without some large m2 of vacuum solar tubes and some very efficient heat storage is just fantasy.
Even if gas rose to 10 times it current price their offering would not have saved me over 6,000 in it's lifetime. And there are much more economic, efficient, ways of being "green".
e.g. Biogas, or wood fuels, or electric efficient heat pumps.
The solarventi is an exception in my view. It does more than just add hot air. It has freshened our bathroom upstairs less over the summer months with the sun so high. But it has been more active as August has passed and the sun's angle of incidence on the panel has increased. Remember the panel is close to vertical.
The dehumidifying action increases too.
I was able to switch off the central heating earlier this year than previous years and I anticipate the central heating will come on later this autumn. I am conscious that the solarventi is part of the reason for this. It's 17 degrees outside this morning but bright sunshine. The central heating might have kicked-in over night (but it's not switched on). But the solarventi was purring away with the early morning sun.
We visited a friend last week, it's mid-August, who had windows on trickle vent/closed upstairs and the mugginess in the bathroom was a reminder where we would have been without the solarventi.
Monday, 1 June 2009
Long hot days
Monday 1st June; we have had a lovely weekend of continuous sunshine here in Peterborough.
I think we have a better understanding of the Solarventi solar unit in this weather.
On the control unit I have kept the max. temp. setting needle at a 2 o'clock position, probably 25 degrees. The needle goes from a temp.setting of 15 degrees at 8 o'clock, clockwise on the dial to a setting of 30 degrees at 4 o'clock on the right of the dial.
The outside temp. thermometer reading reached 25. The solarventi unit stopped running early afternoon. It recommenced at some stage late afternoon I think, I assume once the unit had cooled down. The relative humidity measured 21% on the bathroom hygrometer whilst the unit was running. When it stops, the humidity climbs very quickly back to 40+.
We also leave the bathroom window locked-open. We find this balances the extreme drying capability of the solarventi unit with our need for humidity. You can have too much of a good thing.
In future posts I will continue to give results from our solarventi unit, but in addition I will explore the use of solar power in the form of heat pump / inverter units. These units transfer heat from air outside the house to warm the inside of the house. It will be interesting to see how these investments compare.
I think we have a better understanding of the Solarventi solar unit in this weather.
On the control unit I have kept the max. temp. setting needle at a 2 o'clock position, probably 25 degrees. The needle goes from a temp.setting of 15 degrees at 8 o'clock, clockwise on the dial to a setting of 30 degrees at 4 o'clock on the right of the dial.
The outside temp. thermometer reading reached 25. The solarventi unit stopped running early afternoon. It recommenced at some stage late afternoon I think, I assume once the unit had cooled down. The relative humidity measured 21% on the bathroom hygrometer whilst the unit was running. When it stops, the humidity climbs very quickly back to 40+.
We also leave the bathroom window locked-open. We find this balances the extreme drying capability of the solarventi unit with our need for humidity. You can have too much of a good thing.
In future posts I will continue to give results from our solarventi unit, but in addition I will explore the use of solar power in the form of heat pump / inverter units. These units transfer heat from air outside the house to warm the inside of the house. It will be interesting to see how these investments compare.
Monday, 18 May 2009
Dry throat
O.K. so I should have seen this coming.
The solarventi SV14 unit, in full sun all day, has so reduced the humidity from the house norm of about 60%, to below 20%, (According to our hygrometer display relative humidity is "LO%" which I think means it can't measure below 20%) that it has dried my face and throat.
How silly of me, to sit in the study, down the landing from the bathroom where the solar panel pours in the very, very, dry air. Not only are the towels over the banister like starched sheets, but I need to have a long cool drink every 5 minutes.
The air is so much drier than the outside air, I don't think I was really anticipating the amazing dehydrating qualities of this unit.
I was quite uncomfortable, so I threw the windows wide open; this is May in Peterborough, and outside temps have not reached 20 degrees C yet. Great stuff. But there is a problem. You can't tell what the weather will be exactly, and you can't leave the windows open just in case. And you can't afford to dry the house to a crisp. Literally, arrive home, 2 minutes upstairs and my throat is dry.
The longer term solution, when I am going out for the day and can't leave the windows wide open, is to work-out the best temperature setting on the solarventi controller. It's not too difficult to gauge what temp you have set. The panel's selector needle shows 15 degrees as the lowest value (anti-clockwise) and 30 as the highest. However, when 30 degree air was being pumped into the bathroom, the fan did not hesitate for a moment, it continued at full speed. Perhaps 30 doesn't mean 30?
I don't have the answer to this yet, so I chose something around where I imagine 25 would be, setting the needle at a position of TWO O'CLOCK on the temperature gauge.
I need to ask Solaventi UK for their opinion on the temp.setting best suited.
The other option is to override the fan speed. (This is the other needle on the controller for the solarventi unit) I have concluded that since the dehumidifying aspect of the panel seems to correlate with temp. (higher the temp. the lower the humidity) then setting temp. cut-off at 25 should limit the humidity to a sensible range and suit all weather patterns.
Like today, occasional sunshine, the panel rarely reaches 25, but it is worth having the fan on full power whilst it approaches that temp.
Yesterday, Sunday, when the sun was shining, I was able to check my settings, since the hygrometer showed 24 degrees and 31% relative humidity. This seemed reasonably comfortable to me.
I imagine if customers have installed these larger solarventi units without the controller in their homes, it will prove necessary to switch the unit off in summer. Or lock the windows in an open position. Personally I did not find this enabled enough flow of air into the house.
The driver for me, my aim on installation of the solarventi model, has always been to dry the bathroom and reduce/remove the pin mould problem. No sign of the mould at the moment !!! I am very optimistic on that front.
If my main aim had been to heat the house (upstairs at least) to a very comfortable 28+ degrees then I would now consider it an un-realistic goal, since the dehumidifying behaviour of the unit is too powerful to allow the unit to keep running at that high a temperature with the windows closed, in my opinion.
Wednesday, 29 April 2009
April sunshine
Forget the showers, this last week or so has been sunshine 9 days in succession. How often is April like this? In fact it's another bright day today.
When the sun is shining the solarventi panel has reduced the bathroom humidity; 7am bath is run, humidity climbs to near 100%; with the panel operating in full sun, by 8:30 am the bathroom is registering humidity down to 45%, (bathroom norm by midday on an overcast day is still 65%) .
When I return at 5:30pm (before evening baths) the hygrometer is still measuring the bathroom at 50% humidity, and upstairs along from the bathroom the temp. has still been 23-24 degrees C. This is long after the sun has moved round the house away from the panel.
Downstairs away from the benefit of the hot air from the panel it has been cooler i.e. at the house norm of 20.
I find it very pleasant upstairs. The house is not normally as warm as 24 at 5:30pm even on a warm summer's day. The house doesn't have large south facing windows.
All this and temperatures outside the house have been moderate, between 10 and a max. of 18 degrees C.
So I am pleased with performance these last few weeks.
When the sun is shining the solarventi panel has reduced the bathroom humidity; 7am bath is run, humidity climbs to near 100%; with the panel operating in full sun, by 8:30 am the bathroom is registering humidity down to 45%, (bathroom norm by midday on an overcast day is still 65%) .
When I return at 5:30pm (before evening baths) the hygrometer is still measuring the bathroom at 50% humidity, and upstairs along from the bathroom the temp. has still been 23-24 degrees C. This is long after the sun has moved round the house away from the panel.
Downstairs away from the benefit of the hot air from the panel it has been cooler i.e. at the house norm of 20.
I find it very pleasant upstairs. The house is not normally as warm as 24 at 5:30pm even on a warm summer's day. The house doesn't have large south facing windows.
All this and temperatures outside the house have been moderate, between 10 and a max. of 18 degrees C.
So I am pleased with performance these last few weeks.
Wednesday, 1 April 2009
Hygrometer
On Saturday we had scattered showers, no make that storm clouds, (occasional heavy hail) with the odd patch of blue sky. The hygrometer in the bathroom confirmed the solarventi panel had been in action. When I returned from my travels over lunch, the relative humidity still registered 40%, and temp was 21.7 degrees C. even though the sun was not out that much.
The house "norm" is 55-60% and our central heating is set at 20 degrees.
(Fig 1. Bathroom ceiling, with input vent from Solarventi panel.)
OK, so my hygrometer has fallen from it's mounting, as you can see to the right, it now rests on the wall cabinet (far right, behind the Johnson's baby shampoo bottle). The readings are none the less encouraging. Sunday was dry and bright. The images were taken that afternoon.
As I stood peering at the hygrometer, my breath caused the humidity reading to rise from 23 to 27 in seconds. Humans are a major cause of damp in houses too. Just breathing adds moisture to the atmosphere.
The two temperature readings are internal 27.9, and external 18.4. The wire runs outside to a sensor on the wall behind the solarventi panel. The general outside temp was 10 degrees at the time, or so the car instrumentation said as we drove home from church. So the external temp is boosted by being in proximity to the panel.
Tuesday, 24 March 2009
Sunshine and gas bills
We have had 5 days of lovely sunshine. I have measured 29.9 degrees air temp. at input to the bathroom, and 29% relative humidity.
I trust that is good news, it means it will be drying out the fabric of our bathroom.
The solarventi unit is limited to 30 degrees C output. So that would explain the 29.9 degree reading at the vent in the bathroom ceiling.
The gas bill was unchanging on the year, well actually up 300 KWh on an annual consumption of 11000 KWh. Thats a 3% increase on last year. That is a mere 10 units on the meter. e.g. the gas meter reading was 370 units for the whole of last year, and 380 this. We are low users !!!
I confess that I am disappointed. Not because the solarventi hasn't delivered a small saving but because we replaced the old double glazing, fitted a bubble blanket in the loft for insulation and refreshed the draft-excluder around the front and back-door this time last year.
I guess it was a cold Feb. and the bill might have been much higher without those jobs done.
By the way, I reckon 300 KWh of energy, or 10 units on our gas meter, is probably the amount of energy we could expect to generate from the solarventi SV14 (heating our expanse upstairs) in a 12 month period. (2.5 KWh per day x 10 days per month x 12 months) Very approximately !!!
I trust that is good news, it means it will be drying out the fabric of our bathroom.
The solarventi unit is limited to 30 degrees C output. So that would explain the 29.9 degree reading at the vent in the bathroom ceiling.
The gas bill was unchanging on the year, well actually up 300 KWh on an annual consumption of 11000 KWh. Thats a 3% increase on last year. That is a mere 10 units on the meter. e.g. the gas meter reading was 370 units for the whole of last year, and 380 this. We are low users !!!
I confess that I am disappointed. Not because the solarventi hasn't delivered a small saving but because we replaced the old double glazing, fitted a bubble blanket in the loft for insulation and refreshed the draft-excluder around the front and back-door this time last year.
I guess it was a cold Feb. and the bill might have been much higher without those jobs done.
By the way, I reckon 300 KWh of energy, or 10 units on our gas meter, is probably the amount of energy we could expect to generate from the solarventi SV14 (heating our expanse upstairs) in a 12 month period. (2.5 KWh per day x 10 days per month x 12 months) Very approximately !!!
Monday, 16 March 2009
Bathroom sweet
Sunday, and Monday, 15-16 March 2009.
2 days of lovely sunshine.
It is hazy sun at times, but we noticed the bathroom reach 29 degrees (temperature near the vent in from the Solarventi solar panel), and relative humidity of 30%.
If the ceiling mould (the black spot mould) survives that, then I don't know what the answer is.
It makes the bathroom very fresh.
It makes you want to spend on a new bathroom suite to freshen the look as well.
Saturday, 7 March 2009
Early March 2009
For solar panel users in our part of the country it has to be a great start to the month of March 2009.
We have had good sunshine. The solarventi unit has run for hours.
I am no longer getting complaints from family regarding smell from unit. That seems to be over.
Just fresh air, warmed, and from my view point the early morning sun is perfect.
The bathroom hygrometer shows that when I return home the temp is still over 21c; and relative humidity 60%. The humidity is not as low as it reached in the coldest days of last month, but I guess the days are warmer, so more humid outside. The temperature is holding up well, I think. Or is someone having a secret bath mid-day?
What does this mean. We shall see. The fuel bill will arrive soon. Is it too much to hope for a (slightly) lower heating bill?
We have had good sunshine. The solarventi unit has run for hours.
I am no longer getting complaints from family regarding smell from unit. That seems to be over.
Just fresh air, warmed, and from my view point the early morning sun is perfect.
The bathroom hygrometer shows that when I return home the temp is still over 21c; and relative humidity 60%. The humidity is not as low as it reached in the coldest days of last month, but I guess the days are warmer, so more humid outside. The temperature is holding up well, I think. Or is someone having a secret bath mid-day?
What does this mean. We shall see. The fuel bill will arrive soon. Is it too much to hope for a (slightly) lower heating bill?
Thursday, 19 February 2009
Warmer times
Feb 19th 2009
Temperatures have improved this week. 7 degrees C today.
Sun was shining. 9am and the bathroom seemed to be full of warm fresh air.
We have gas fired central heating. Gas is currently 7p per KWh of energy.
If the Solarventi solar panel produces 500w heat energy per hour, that's potentially 3.5p per hour saved.
But more than that, the lower humidity might reduce dust mite activity, mould in the bathroom and apparently water moisture is expensive to heat, so a less humid house is cheaper to heat. SolarVenti UK link
Temperatures have improved this week. 7 degrees C today.
Sun was shining. 9am and the bathroom seemed to be full of warm fresh air.
We have gas fired central heating. Gas is currently 7p per KWh of energy.
If the Solarventi solar panel produces 500w heat energy per hour, that's potentially 3.5p per hour saved.
But more than that, the lower humidity might reduce dust mite activity, mould in the bathroom and apparently water moisture is expensive to heat, so a less humid house is cheaper to heat. SolarVenti UK link
Friday, 13 February 2009
Snow blanket
Photos, both taken Friday 13th Feb 2009. 9 am.
Peterborough had more snow fall last night. And temperatures dropped to -1 perhaps -2.
On the driveway, a car has a snow blanket, which has frozen, then started to thaw.
(The cotton blanket at the bottom of the windscreen just protects the wipers and spray jets overnight)
The same morning, 9am the solar panel is warming up.
Another dry (cold) sunny day in prospect. 
By this time of year, the sun is now high enough by 9am to ensure the shadow from the house next door does not cover the panel.
If you are contemplating solar panels on your house, even if the neighbouring houses are close, (approx. 8 metres apart in this case) the angle of the sun is enough to reach a well positioned panel.
In this case the panel is not vertically attached to the wall, but it's approx. 30 degrees from the vertical on a pair of aluminium stands. I understand these would normally be used if siting the panel on a tile roof, but here they serve well to maximise the exposure to the sun at this time of year.
Sunday, 8 February 2009
Winter sunshine - Feb 2009
Sunday 8th Feb 2009.
This week we have had 3 days of sunshine and glorious blue sky, and other days snow showers.
The media refer to this past week as the big freeze in the UK.
Southern counties have had more snow than usual that is true. But Tuesday, Wednesday and Saturday were beautiful days.
I made myself a nuisance on Tues, & Wed calling home to ask my wife to turn the fan speed up on the Solarventi controller. Saturday was such a lovely crisp bright day. I had a driveway to clear of snow, again.
Of course, such days are dry, and should be "tailor made" for the solarventi solar panel that is stuck on the side of the house. The dry air, and bright sunshine (the outside temperature rose to about 3 degrees C) caused the unit's fan to kick into action from 9am onwards, even though the sun was still low in the sky.
I monitored the humidity in the bathroom, it fell to 34%, (from a house norm of 55-60%) and the temperature in there held above 22 degrees C. (I should point out that the central heating is set at 20.) I guess that means the room was being dried effectively. Certainly all windows upstairs lost their usual inside surface moisture.
The solarventi panel and fan was working at full blast as far as I could tell. The controller was set to full fan speed. Whilst the sunshine was bright, so the unit worked, until 3pm, where the sun is too low this time of year.
The wall is South South-East facing, i.e. slightly east of due south, so it will do better in the morning, as the days get longer.
One point I should make is that the unit has produced an vague odour since installation (3 weeks ago now), but it's now diminishing. My wife describes it as smelly socks. I guess it is like a new car smell. It wears off eventually.
This week we have had 3 days of sunshine and glorious blue sky, and other days snow showers.
The media refer to this past week as the big freeze in the UK.
Southern counties have had more snow than usual that is true. But Tuesday, Wednesday and Saturday were beautiful days.
I made myself a nuisance on Tues, & Wed calling home to ask my wife to turn the fan speed up on the Solarventi controller. Saturday was such a lovely crisp bright day. I had a driveway to clear of snow, again.
Of course, such days are dry, and should be "tailor made" for the solarventi solar panel that is stuck on the side of the house. The dry air, and bright sunshine (the outside temperature rose to about 3 degrees C) caused the unit's fan to kick into action from 9am onwards, even though the sun was still low in the sky.
I monitored the humidity in the bathroom, it fell to 34%, (from a house norm of 55-60%) and the temperature in there held above 22 degrees C. (I should point out that the central heating is set at 20.) I guess that means the room was being dried effectively. Certainly all windows upstairs lost their usual inside surface moisture.
The solarventi panel and fan was working at full blast as far as I could tell. The controller was set to full fan speed. Whilst the sunshine was bright, so the unit worked, until 3pm, where the sun is too low this time of year.
The wall is South South-East facing, i.e. slightly east of due south, so it will do better in the morning, as the days get longer.
One point I should make is that the unit has produced an vague odour since installation (3 weeks ago now), but it's now diminishing. My wife describes it as smelly socks. I guess it is like a new car smell. It wears off eventually.
Sunday, 1 February 2009
Experimenting
Solarventi controls include fan on/off, variable fan speed, and maximum temp.
Max. Temp? That has bothered me slightly since I first read about it. (http://www.solarventi.co.uk/ has some details, UK prices etc., and http://www.solarventi.com/ has .pdf documents and further info.)
In fact, I asked the installer, from solarventi UK, to clarify was the temperature setting the minimum temperature, or the maximum that air should be vented into the property.
Answer: it is the maximum. The setting is intended for summer time, when you don’t want hot air pumped into the house. It cools itself, by blowing the air out (I think?).
It struck me that I would prefer to also have a minimum temperature setting, say 20 degrees.
That would prevent the fan starting until the air captured in the unit has been warmed to at least match the temperature in the house?
I have slightly re-evaluated my point of view. The week and a half since installation I have not been in, or there has been very little hazy sunshine at weekends. The fan makes a little effort in hazy sunshine, and cool air appeared to be pumped into the house. Virtually nothing happened it seemed to me.
Saturday, 31st January 09, with a bright clear morning, and a little time on my hands, I could see what was going on. It seemed at first that cooler air than room temperature was entering through the vent. What should I do? Think.
The outside temperature started that morning about 4 degrees C.
I thought about the controls. How can I get the air temperature I want, and the fresh air I have boasted to the wife about, at the same time, on a cold day like this? The fan was on full speed, as I had left it.
At regular intervals, I experimented with the fan speed, and checked the temperature and humidity in the bathroom, at the vent, and 50cm away from it for an idea of general room temperature.
This was the concept I developed. Number 1. You can't really estimate to what temperature the air will rise. The air actually needs to be drawn through, otherwise you won’t know if the air at the fan has risen enough, nor if it is dry air (low humidity will have the beneficial effect of drying the room).
Number 2. If that's the case, what fan speed? So I slowed the fan speed, and found the air temperature produced at the vent into the bathroom increased. I figured the air has more time to warm in the unit. I was pleased to see the hygrometer (humidity gauge and thermometer) climb to 23.1 degrees C next to the vent, (2 degrees more than room temp) humidity was 58 in the room and gradually over the morning, the vent produced air as low as 41% relative humidity.
So with the fan on full speed I was letting cooler air in, but was it dry? Not as dry as it was by lunch time, when the unit seemed to be delivering on my expectations. By this time I had moved the fan up to half speed, and sacrificed a degree in temp. for what I considered to be loads more volume of dry air pumped in.The upstairs in the house seemed fresher, but it also had a slight draft, as you would expect.
I am sorry to say lunchtime saw high cloud obscure the sun for the rest of the day.
But lesson learned, I think; when the system is struggling in early morning sun, in January, you will have to put-up with lower temperature air or turn the fan down low.
I have compromised for now and set the fan to just under half speed, for the next few days may be bright, but are forecast to be very cold.
But lesson learned, I think; when the system is struggling in early morning sun, in January, you will have to put-up with lower temperature air or turn the fan down low.
I have compromised for now and set the fan to just under half speed, for the next few days may be bright, but are forecast to be very cold.
Friday, 23 January 2009
First steps to using solar energy
Solar? Saving on energy consumption in the home? Are you serious?
Well yes I am.
I have for several years looked at the various merits of solar panels. (Ground-source and air-source heat pumps are another subject for another time)
By now I reckon I have a pretty good appreciation of the subject. (I may look back on this blog and realise I was wrong)
I have investigated water heating panels (flat plate, or vacuum tube), PV panels generating electricity, and air heating panels (most of these seemed to have a ‘home-made’ feel about them, in the USA some types are made with old soft-drink cans!)
I enjoy reading the technical stuff like average UK daily “insolation” (sun’s energy) each month of the year, I find this fascinating. And energy conversion ratings such as watts (w) energy output per hour in overcast, bright or very sunny conditions are published by some vendors. This gives you an ability to compare raw numbers for different units. I shall come on to some of the details in a minute.
The issue for me came down to initial investment cost, and complexity.
I wanted to produce some heat in the house from the sun. I knew it was possible. But which solution should we choose?
Some of my findings.
PV solar panels, generate very little energy for each M2 (square metre) of panel. OK it’s easy to carry the energy inside the house, because it’s electricity that it generates, but the best on the UK market are still only 16% efficient. And I was expecting to pay £500 for a 200w (max. rating) electric panel.
That’s before installation, where an inverter is required (£600) to convert 12v (Volts) to 240v. (Grid tie inverter, plug the output into a socket, and voila, electricity straight to the rest of the house)
The panels have to be big to achieve this 200w output.
Around 1000 watts of energy are present during regular sunshine for each 1M2 of UK land surface. Therefore 16% efficiency means the panel must be 1M2 to generate 160w of energy.
Water heating panels (vacuum tube especially) are efficient at capturing the sun’s energy, but you need all the water pipes, pumps, non-return valves, pressure release valves (for July sunshine) and a radiator within the property on a closed loop.
You can of course use the energy to heat your tap water. But the hot water bill in summer for us is about £18, (our summer quarter bill is always very low) and the system plus install would be about £2000 for tap water heating.
So I thought perhaps air heating was my best option. It seemed less complex, less parts, easier to install and therefore slightly less expensive. The guide price for the large unit “SV14” we were considering on the http://www.solarventi.co.uk/ web site was around £900 plus vat, plus install. It was claimed that up to 600w energy could be produced. The unit is 2M x 0.7M, i.e. approx. 1.4M2.
Simply, the Solarventi models aim to heat out-side air and push it into the building thus contributing to a recycling of air that is in the house. Stale air inside the house is pushed it out through those cracks and crevices around windows, doors etc.
It is rated highly any time of year, but particularly on those winter days when the sun is low, the ground is frosty, and the out-side air is very dry (low humidity).
Why is that important? Well, low humidity air in winter, can, it is claimed, in effect dry your house. Moisture takes plenty of energy to heat. So, unless you have a grand-piano with a requirement for moisture, it’s a good idea. We are hoping that in winter moisture around the inside of windows will also reduce over time.
The Solarventi solar panel is installed out-side on a wall or roof. It sucks out-side air into the unit, warms it and a PV panel generates a small amount of electricity to drive a fan to impel the air into the house.
Our unit only seems to work in bright sunshine. But that’s the idea I guess, bright winter sun equals dry, crisp air outside. Over the months we should see a warming of the house, and a drying too.
So where did we install the Solarventi unit? It’s on the external wall outside the bathroom, facing south, of course. Ideal we hope for capturing low winter sun.
We had a choice where the vent into the house should be piped, through the roof space, from the unit. But we chose the solarventi to vent into our bathroom.
At least it will when we next have a bright sunny day. Wed. the day of the install was bright and sunny, and the unit worked fine as we inspected it before it was lifted in place onto the wall. It has been overcast since then.
I have a couple of photos of the install, and over time I will report on the results. The installers kindly helped me install a hygrometer, (humidity gauge) which has a remote temperature sensor. They placed the sensor on our outside wall next to the solar panel. So I have been taking daily readings of inside temp, inside humidity, outside temp. and recording the amount of bright sunshine.
The challenge then for this solarventi unit is, over time, to reduce the humidity (and unsightly mould) in the bathroom in particular and we are told to expect the other rooms upstairs to benefit also.
We shall see.
Well yes I am.
I have for several years looked at the various merits of solar panels. (Ground-source and air-source heat pumps are another subject for another time)
By now I reckon I have a pretty good appreciation of the subject. (I may look back on this blog and realise I was wrong)
I have investigated water heating panels (flat plate, or vacuum tube), PV panels generating electricity, and air heating panels (most of these seemed to have a ‘home-made’ feel about them, in the USA some types are made with old soft-drink cans!)
I enjoy reading the technical stuff like average UK daily “insolation” (sun’s energy) each month of the year, I find this fascinating. And energy conversion ratings such as watts (w) energy output per hour in overcast, bright or very sunny conditions are published by some vendors. This gives you an ability to compare raw numbers for different units. I shall come on to some of the details in a minute.
The issue for me came down to initial investment cost, and complexity.
I wanted to produce some heat in the house from the sun. I knew it was possible. But which solution should we choose?
Some of my findings.
PV solar panels, generate very little energy for each M2 (square metre) of panel. OK it’s easy to carry the energy inside the house, because it’s electricity that it generates, but the best on the UK market are still only 16% efficient. And I was expecting to pay £500 for a 200w (max. rating) electric panel.
That’s before installation, where an inverter is required (£600) to convert 12v (Volts) to 240v. (Grid tie inverter, plug the output into a socket, and voila, electricity straight to the rest of the house)
The panels have to be big to achieve this 200w output.
Around 1000 watts of energy are present during regular sunshine for each 1M2 of UK land surface. Therefore 16% efficiency means the panel must be 1M2 to generate 160w of energy.
Water heating panels (vacuum tube especially) are efficient at capturing the sun’s energy, but you need all the water pipes, pumps, non-return valves, pressure release valves (for July sunshine) and a radiator within the property on a closed loop.
You can of course use the energy to heat your tap water. But the hot water bill in summer for us is about £18, (our summer quarter bill is always very low) and the system plus install would be about £2000 for tap water heating.
So I thought perhaps air heating was my best option. It seemed less complex, less parts, easier to install and therefore slightly less expensive. The guide price for the large unit “SV14” we were considering on the http://www.solarventi.co.uk/ web site was around £900 plus vat, plus install. It was claimed that up to 600w energy could be produced. The unit is 2M x 0.7M, i.e. approx. 1.4M2.
Simply, the Solarventi models aim to heat out-side air and push it into the building thus contributing to a recycling of air that is in the house. Stale air inside the house is pushed it out through those cracks and crevices around windows, doors etc.
It is rated highly any time of year, but particularly on those winter days when the sun is low, the ground is frosty, and the out-side air is very dry (low humidity).
Why is that important? Well, low humidity air in winter, can, it is claimed, in effect dry your house. Moisture takes plenty of energy to heat. So, unless you have a grand-piano with a requirement for moisture, it’s a good idea. We are hoping that in winter moisture around the inside of windows will also reduce over time.
The Solarventi solar panel is installed out-side on a wall or roof. It sucks out-side air into the unit, warms it and a PV panel generates a small amount of electricity to drive a fan to impel the air into the house.
Our unit only seems to work in bright sunshine. But that’s the idea I guess, bright winter sun equals dry, crisp air outside. Over the months we should see a warming of the house, and a drying too.
So where did we install the Solarventi unit? It’s on the external wall outside the bathroom, facing south, of course. Ideal we hope for capturing low winter sun.
We had a choice where the vent into the house should be piped, through the roof space, from the unit. But we chose the solarventi to vent into our bathroom.
At least it will when we next have a bright sunny day. Wed. the day of the install was bright and sunny, and the unit worked fine as we inspected it before it was lifted in place onto the wall. It has been overcast since then.
I have a couple of photos of the install, and over time I will report on the results. The installers kindly helped me install a hygrometer, (humidity gauge) which has a remote temperature sensor. They placed the sensor on our outside wall next to the solar panel. So I have been taking daily readings of inside temp, inside humidity, outside temp. and recording the amount of bright sunshine.
The challenge then for this solarventi unit is, over time, to reduce the humidity (and unsightly mould) in the bathroom in particular and we are told to expect the other rooms upstairs to benefit also.
We shall see.
Installation
Wed. 21st Jan 2009.
Thank you Jesus, it is a dry bright day for installation. (You are a bit too exposed installing a 2 metre solar panel on a south facing wall for it to be raining or snowing!!)
The staff from Solarventi were booked to perform the installation. Good communication prior to the day regarding the layout (inside and out), suggested to me the install would be successful. I was pleased with the communication on the day; discussion and explanation of the approach to the work made me feel well informed.
The gadget just before it is raised up the scaffold.Aluminium backed unit has many tiny perforations to allow air into the unit to be warmed and vented into the property. The vent output is pictured at the top next to the regulator cable. The cable was fed into the house to a rudimentary thermostat / control unit placed on the upstairs landing.
It should give adequate control over the panel output.
December and January have been cold and dry for the most part. The forecast is for rain for the rest of the month.
Hmmm...
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