SteamyTea

I shall try. What I think would happen is that the HP would run for longer, using more energy. I tend to think of a HP working with 'packets' of energy. So imagine you have a large box of cool air, you squeeze it down, thus making it smaller, but hotter. We have a simple formula for this PV/T = C. So now imagine that you are about to squeeze the box even smaller, you will need more power to do that (but you don't have a bigger motor), and it will take longer, bit like sitting on a packed suitcase to close it. C stays the same (think of this constant as your CoP, so Cn, where n=0 to infinity). So yes, you can make your own 2 stage pump, but you will gain nothing (you will actually loose to general thermal losses).

A lot of it depends on the nature of your business and the organisational skills of the office manager/administrator. And the motivation of the staff. I used to just use lists of what needed doing and trusted my staff to do what was needed in the easiest manner for them.

I think it would kill the heat transfer. When water 'falls' down a vertical pipe, it actually swirls around the inside of the pipe wall. Put that same pipe horizontally and you create a D shape (twiddled over 90°), this has a much greater volume to area ratio. That will ruin the heat transfer. When we discussed this a few years back, I took a different route from Jeremy and looked at transferring heat in a batch method. Basically the waste goes into a holding tank, then via a heat exchanger into the cold water storage. It worked, but was slow, needs space and was not cost effective at all. This idea could be modified with a W2WHP, but then getting even more costly. Main thing is to do the sums first. A normal shower should not need more that about 50 kg of water at 38°C max. Incoming mains in winter is probably very rarely below 8°C. So: 50 [kg] x (38 - 8)[°C] x 4.2 [kJ.kg-1.K-1] = 6300 kJ or about 1.7 kWh That is about 32p at my expensive day rate, 14p at my night rate. Now a 250lt tank to service 4 people with hot showers is right at the limit of its capability, so probably storing at 65°C (or maybe a bit more), but the mean temperature will probably be nearer 55°C, so that is 49350 kJ or 14 kWh. This will probably give you standing losses of around 4 kWh/day so you have 10 kWh of usable energy in the hot water (losses between 32p - 72p.day-1 or £117 to £265.year-1). So look at insulating the store more and reducing the temperature a bit. A couple of sheets of Celeotex type material will cost 50 quid. Turning down the temperature costs nothing. Another method is to get an aerating shower head, had one when I lived in the USA (it also pulsed and did wonderful things on other settings). it worked well, but the flow was still very high. I would like to try one out on my lower (11 kg.min-1) flow shower here. Another alternative is to bite the bullet and get instantaneous water heating (maybe in series with a Sunamp/PV). If that costs £7000 to install, and you can save close to £300 a year, then 'only' 23 years till you hit break even. Easier to use less.

Maybe a quick diagram would help.

Me too, have never worked out the sentimental attachment to pets. Why can't we have a referendum to ban all pets. Would get my vote.

If we all worked 4 days a week only, we would all be better off, and reduce transport costs by about 20%. When I introduced 4 day weeks at my factory 25 years ago there was great resistance to it, even though the 'lads' had to work for 1.5 hours a week less for the same money. Productivity shot up, factory costs went down and eventually people became happier.

Not looked at anyone else's answers, but have seen this before. Change the + to * and add one to the second number. so 8+11 = 8*(11+1) = 8*12 = 96

We used to install SMA's and Fronius, both are good and you can get the data off either. Unless you have shading problems, I cannot see any advantage of micro-inverters.

If you are not too bothered by the accuracy, you could use current clamps and an appropriate reader/logger. The ones I use allow 9 clamps to be wirelessly connected. It will give you a good enough idea about what is happening.

I think this is the wrong way around (and I think I may have posted it originally too) Square meter is shape dependant, e.g. a rectangle of 1 m length by 1 m width. A metre square is not shape dependant, e.g. the surface area of the Cornwall (as it is a really odd shape) 3.563824e+9m²

This highlights the difference between Power and Energy. If you draw power that is greater than the wind turbine is producing, then it tops up from the grid (an import), regardless of how much energy the turbine produces over a year. You also need a high windspeed to get close to the maximum generation capacity of a turbine. You may well find that the load factor is quite low.

Do they now

Is that why we have the most expensive water and sewage costs in the country, they need to buy a lot of sunglasses!

This highlights the problem of subsidies. I have often thought it is wrong to pay people to add extra load on the grid, but I suspect that it goes back to the old 'nationalised' National Grid. It was considered a market failure, so the cost was covered by the state. Since privatisation this has changed and it is very easy to charge to generation companies for the service as there are not too many of them. The administration costs of charging 1 million plus private generators is a different matter. I think I currently pay £0.18/day for my meter rental, so that is about £65/year. If I am also paying £140/year to the National Grid, that is a total of £205/year. This is equivalent to about 1,367 kWh/year, or about a third of my usage. I could buy 200 lt of diesel (2,000 kWh/year) and generate my own electricity and thermal energy (circa 1,200 kWh/year), so getting close to parity before capital expenditure and maintenance to go off grid. But a lot of faff to do so.

"Friends from all over the world, non from this country"

When your PV system was installed, a design drawing of the system should have been sent to the DNO. It would show location of modules, inverter, isolators, meter... as well as the type approval. I have no idea what they do with this info but I do know, that if it is not correct, the system needs to be shut down and rectified. So adding 'something else in' still needs notification. I see it as akin to driving with a bald tyre. Most of the time it is fine, but you can get pulled up for it (administrative) or have an accident (safety).

It is sending out the wrong message though. The consequences if something goes wrong, either administratively, or safety, would be tiring at best, prison at worse. Have a word with the DNO and see what they say.

Called a weighing scale on WeightWatcher day isn't it

Can send it to me too and if I get time, I will show you some different results

Put in 3 or 5 sensors in a diagonal line from the brightest corner to the darkest corner. That way you can get a gradient across the slab and eventually just use the one that gives you the closes match to what you need to control. Make sure you know where they are, so if you place any furniture or extra runs over them, you know. If you have MVHR, put the air temp sensors in the room outlet, will almost certainly give a better result, except above a cooker.

It is always worth knowing why you want to monitor something as this denotes what you can do with the data. Let us take a simple slab as an example. You can just put a sensor in the centre (but which centre) and sample the temperature every day at the same times i.e. every hour. On its own, that will not tell you much. All it will record is the temperature at that point at those times. It has nothing to relate to. So let is add another temperature to do room temperature. So where do we put this one. Hanging from the ceiling so that it is in the centre of the room (assume it is a simple rectangle floor plan), or hide it in a corner, maybe at seat height, or low down, under a sofa or fridge. Will it be affected by sunlight, draughts, mechanical air extraction? Once you have sorted those out, you can now start comparing your two data sets. There are 3 main ways to do that: Temperature Difference Binned Mean Temperature Data Sets (quite tricky to set up) Time Series Data They will all give you different results, so you need to know what you are doing it. But that still only gives you a comparison between two points at any given time (slab and air temperature), so it is probably worth getting another sensor to do external temperature (or a local weather station to get data from). Even then, it is only comparing temperatures and with a relatively large margin of error (there are statistical methods to show the bounds that are easy to set up and use). The trouble with just measuring temperature is that you will not know if, it is the internal air temperature, or the external temperature that is affecting your slab temperature, or the slab temperature that is affecting your internal air temperature, as they both may be affected by the external temperature, or the insolation, or maybe the wind speed (has a greater affect than anything else at my site). So you can see that is quickly becomes tricky to know what to measure, and when, where and how. Now two simple scenarios: Control internal air temperature from slab temperate Establish relationship between slab temperature and internal air temperature To control internal air temperature from the slab temperature is quite simple, you just plot slab temperature along the x-axis of a chart, and internal air temperature along the y-axis, draw a line of best fit (spreadsheets are excellent at this) and you will end up with an equation (stick to a simple straight line y=mx+c). As you have forced the 'controlling' factor, the slab temperature onto the x-axis, by knowing that temperature, you can just read of the chart what the air temperature should be (there will be margins of error). So if the slab gets cold, you heat the air, if it gets hot, you cool or replace the air. Simple, but crude. Much easier to just control the air temperature from the air temperature, it will be more accurate. To establish relationship between slab temperature and internal air temperature is really just a matter of collecting enough data and plotting the slab temperature against the internal air temperature, but without, or allowing for, external factors. So no heating, cooling, bulk air movement (sealed room), then look to see what the time difference is between changes. So you can start by slicing the data up into seasons, months, weeks, hours of daylight, intensity of sunlight, wind direction, wind speed, rainfall, curtains opened or closed, room usage etc, and just compare that to the 'sealed room' data. This will usually need the logger set up differently, so rather than sample at fixed times, you sample at fixed temperature differences i.e. every half degree. Then you look at the lag times, these will usually overlap because of the differing thermal properties between the slab and the internal air. You can then start to interpret the data and see where the variances are, but you still need to know why you are doing it. So assuming that it is for internal temperature control, you can create a large data array that allows you to set the heat input parameters i.e. how much and how long to heat, from the historical data i.e. slab is 2°C below optimum, I need 3 kWh of thermal energy in the room in the next 7 hours, or whatever. So after that ramble, decide why you are doing it first, then how you will do it, then what you will do with the data. Before long you will be an expert at conditional data manipulation.

Start reading: https://www.gov.uk/government/publications/electricity-market-reform-contracts-for-difference I think there are several different ways that a PV generation company can sell their produce, just a case of someone sitting down and working out the best contract to be on. If you take out the CO2 element, they are just like ordinary, small scale, producers and can enter the auctions when the price is right. So they may elect to just sell power for the morning and evening peaks in the summer and give power away the rest of the time. This, if there is enough solar being generated, will affect the market price. That is a risky game to play though as they may have to 'buy in' power when they cannot supply, and that will be very expensive as it is calling on the 'hot spinning reserves'

Have you really forked out nearly £50,000 before you actually start the real work?

I come from a production engineering background, I don't see that as a problem.

If you are using a lot of timber on site, and most houses seem to have more timber than anything else, why not buy a cheap, but adequate, planer thicknesser and save yourself a lot of time and hassle.