Carrerahill

Argh... who resurrected this ancient post!?

Assume long cable runs or something? Tricky install? If all short local runs and easy install, then it's about £350 too much.

Don't. Simply don't. There is no such thing as an hour of work. I am a consultant engineer, the minimum we charge is 1/2 a day and even then we need to be pushed to offer a 1/2 day. Work in days, unless you really cannot justify a day for something but then we usually just lump it in with something else. We were asked to update 3 cable lengths on a site distribution design schematic this week, I had to review all the info, run the model again to get the new cable sizes (which also impacted switchgear and sub-mains further upstream), passed the drawings to CAD for updating, I then checked them, CAD updated the drawing issue sheet, created an issue folder, made a share link, I typed a cover email and issued. The client would see that as 3 cable sizes being increased, and a drawing tweaked, it took us about 4 hours all in. Generally we allow 1 day per typical drawing, obviously that might sometimes change if there are very little details or loads, i.e. a small power drawing might take 2 days, for a larger office, or you might get 3 floors (3 drawings) of a small office done in 1 day. That is based on locked GA's being issued to us and design development tweaks are included, anything bigger is a variation which we hit as a fee all together and work out how many days it might take to do them all. We then allow 1 day for say calcs package for a service, 1 day for schedules etc. Another example, if the architect changes things and issues new GA's even updating all the xref's (properly) so we can reissue drawings on up to date drawings, even if we have no changes, it can take days by the time you strip the architects drawings, clean them up (most of them are a total mess and drawn badly at a CAD level), convert them to a single colour (we use a mid grey ACAD colour 8), save them off as new Xref's with date and issue details registrar on them, then up-rev all the drawings can take 2days even on a small job. The first thing you need to work out, are what your deliverables are, then work out how long each stage will take you. We often issue a drawing issue sheet (DIS) early on populated with all the drawings and schedules we expect to issue, energy modelling we usually work on weeks not even days. That doesn't really answer your question, but I would think depending on your overheads you need to work out what you need to make. A consultancy these days, day rate, is about £400 for a junior engineer, £600 a day for a senior engineer, £750 for an associate, £850 for a director. Typically a project will be priced on a senior engineer day rate. Assume you will have CAD, SE software, Tekla or something, etc. Get your monthly costs for them, + insurances and running costs, then work out what they cost you per day. Then include them in every day you work. If you only work 3 days a month that will be skewed but you get the idea.

I am going to work on that! I have some unconventional ideas. I am now thinking I need a little cylinder which I would use to preheat water going into the combi, or I might use it to charge a battery bank in a more unconventional way, i.e. a battery charger that gets powered up when export meets or exceeds typical charger demand - that sort of thing. I have a 24VDC PV system in the garage which as of yet has no load on it (only got the solar charge controller 2 weeks ago) which I am going to use to feed a small inverter and run all my garage lighting and garden/house external lighting from, so I have options. It is as much about tinkering for me as anything else.

It has all these things and live monitoring via a portal etc. so I suspect that can be used indeed. Just need to tie it all up.

I know some members on here have done things like this before, so I am looking for a little guidance. I want to make a sort of PV traffic light system which I can in turn use to control some loads. We do not have a cylinder so an iBoost is of no use to me, but what would be of use to me is a monitor that can switch on outputs or give us a bit of a heads up we have some spare PV to make use of. My thinking is the best way to do this would be an Arduino monitoring a CT meter or meters (mains incomer and PV), it can monitor what is going on and I can then write some code to carry out different tasks at different thresholds. Let's say I had a spare kW, I could kick in the water heater in the garage or something. I am aware things can probably be bought to do this sort of thing, but there is no fun or learning in that and as I see it the less I spend on the PV related components the better the sooner the payback!

Many replies and lots of info, forgive me if I do not respond to each directly but to respond to some comments, yes it seems many of you have got the typically combustible surroundings that so many PV inverters have, I think I have decided, well I have, because I only bought enough cable to do it this way, I will put the inverter into the eaves space, it will be mounted onto a Unistrut frame on a brick wall, I will line the roof above with 2 sheets of plasterboard to make myself a little happier. I am going to monitor the temps this summer and see how hot it gets out there, if the temps get too high I will add a duct to cover this area for ventilation.

I am certain your concrete will crack over the pipes, however, does it really matter in this makeup, probably not, you could throw some mesh in but you will then struggle with your 50mm cover. Stronger mix with fibre in it... but then again, thinking about what it is doing and the fact the cracks will be adequately bridged by the PIR, I don't think you will have an issue.

They called poor John, "Really old" he doesn't even look that old!

We are going to be oversized on the inverter but within efficient parameters as the start-up voltage is quite low, so it should never get too hard a workout.

Agree 100% with all of that. It's just if there was ever far too much thermal energy I would worry a bit! Maybe I line the area in fireboard and be done with it...

Why don't you just get a roof company to make you vaulted ceiling trusses? You get your roof made and they design it...

I am increasing my PV array next month and this will involve switching to a bigger inverter with dual MPPT, I need to tweak things and move things about a bit anyway so it's time to reconsider the location of the inverter. I really don't like the idea of them in my house. The fairly common place is for them to go in the loft, in my case south facing eaves, not ideal. I design PV system into buildings all the time, commercial inverters go anywhere from the north side of a lift shaft overrun to the plant room, in flatted developments it's fed into the landlord supply so the inverter can go anywhere from a ventilated riser cupboard to a roof void. So it's common enough, but I am still not 100% sold on them going inside, it is possibly an irrational fear, perhaps as a building services consultant I understand all to well the weakness of these systems and the point(s) of failure which can lead to fire. I have made an executive decision to, for example, remove all the MC4 connectors from within the house. I am going to replace the panel mount MC4 connectors on the inverter with a small cable gland and dress the DC cables directly into the inverter and terminate them directly into the screw terminals on the built-in DC isolator (I'll cross the bridge that is the warranty issue if it comes to it). That removes 12 points of failure (crimp on each side of the MC4 and the interface between the pins over 2 strings). However, it got me thinking, the inverter is IP65, it could go outside, I get mixed information when you do a search on this, some articles say, yes great idea, outside in the shade, could not be better, others comment about the inverters being exposed to the elements etc. I get that, but there is no reason why I couldn't protect the inverter further. I had considered a feeder pillar (yes like you see on the street), but I think that would look too commercial, so I considered a wall mounted enclosure, something like a 800x800x250mm enclosure I could mount low down on the outside, side of the house, I can get one with fans which I could run via a temperature sensor, but a bit pricey for all this. I also considered putting them in the garage, I could mount them low, so if a fire did occur the concrete floor and block walls are not going to combust, but I would then need to run the DC cables down the house, across the path somehow (no spare ducts) and into the garage, probably totalling about 30m runs, I considered making a double/triple fireboard lined plant area in the eaves and adding good insulation to stop solar gain via the roof and mechanically ventilate it on a temperature sensor. So, I think I am just looking for some collective input from the forum, some thoughts and ideas, some irrational fear counselling maybe...

Why don't you buy your lights from China, but invest in a decent quality power supply? I usually use Meanwell or EldoLED for things like this.

Do the maths on material and time difference, but we just increased the timber size for the frame, think we went 2x7 in the end for our kit. Meant everything was insulation and service void ready in 1 go and gave us nice chunky TF. It saved having to batten it all out, the material costs, nails, time etc. etc.

When we did it, I measured the opening in the TF and provided that to the manufacturer clearly, in bold, as actual measurements deductions to apply, they made deductions. When they arrived I slid them into the openings then added my 50x50mm treated timber around the openings and I was able to pull them in tight to the windows, they were faced with DPC then the block work was built up to and over the frame by about 1-5mm. I still used the proper brackets so to remove them you could just remove the internal linings and pull them out, but the fit was essentially tight.

What are you going to light with them? I know what you mean about cost, I bought 6, circa 40mm downlights with white bezels about 7 years ago for a plasterboard shelf detail I built down each side of a chimney breast and they were about £40 Ea. at the time.

Ah, didn't read the 1/3W was different models, I thought they were being typically Chinese about the spec of the chip at different voltages. Those are suggesting to be 95Lm per watt, so 285Lumen.

Should do. Do you have any old power supply that is output DC between 12-24V? Favourite of mine back in the day was a Hornby trainset supply. Used to use it for all sorts before I got my lab power supply.

Right, I have just looked at the transformer you bought, it is a half amp 24VDC power supply. How many of the little LED lights do you have? Are you overloading it? They state they are 1W/3W - LED's are funny, I would say at 24V they will be 3W as they are pulling more current as the forward voltage goes up, so do you have too many on it and thus are overloading it?

Maybe you have, but did you not say there was a minimum load?

Their is nothing to suggest they are CC. If they were a current would be listed somewhere. 12-24DC. Hook one up to your car cigarette lighter or any other 12-24DC power supply you have and it will work.

Having looked at the spec on AliExpress is says the input voltage is 12-24VDC - get a DC supply in that region capable of the wattage you need (add them all up for total wattage) and it will work.

No, they are incompatible, the driver behaves like that as it is ascertaining the characteristics of the LED, the fact it keeps going says they are not compatible.

Driver will be seeing that as open circuit and is pulsing the output "looking" for the load. Because of how drivers work, they need to work out what the drive voltage will be, so on startup they sort of ramp up until they detect the forward voltage of the LED (the point it starts to emit light) then they can drive it up will they get the rated current of the driver. Looking at those, I think those LED lights are just 12V because if they were say 100mA they would usually list the current not the voltage, 12V is also quite specific and few LED's will be a nice round, industry standard voltage like that.