So now I have a solar PV system how do I make the most of it???

EricMears

solar_learner wrote: »

I have 2 monitors on different wavelengths so 1 of them measures what is being produced by the panels and the other monitor tells me what i'm currently using....

At the risk of sounding like a commercial for Wattson meters, can I mention (yet again) that a Wattson can accept up to three inputs from cables where you know you're measuring usage and add them together plus one input from a generation cable then display a nett usage figure.

The only snag I've found is that transferring results to a computer can only be done on an historical basis so it's not really practical to use the data for real-time control of equipment that you want to run on your 'free' electricity. Still investigating that but meanwhile I keep my eye on the Wattson and can switch on (say) washing machine when there's a couple of kw surplus and weather forecast suggests that will last for a couple of hours.

Martyn1981

Kernel_Sanders wrote: »

Except that in your case, some of the 'roundabouts' in late spring and summer will be occurring in what (to me) are still the early hours, so difficult to utilise. Are you an early riser by any chance?

Yeah, usually up by 6am, got to 'stab' the cat (he's diabetic) anyway. Sweet spot is 10am to 11am, though to be honest I get really good generation till 2pm, or 3pm BST. Then 300W to 400W till an hour before sunset.

Did see the bigger inverter power up at 6.05 in early August (the smaller one wasn't running till 2 weeks later). Will be interested to see what time the little fellah will start at in late June.

Mart.

EricMears

Martyn1981 wrote: »

Will be interested to see what time the little fellah will start at in late June. Mart.

On 21st June, Sunrise in London should be at 04:43 and Sunset at 21:21 (BST I presume)
from http://www.timeanddate.com/worldclock/astronomy.html?n=136&month=8&year=2011&obj=sun&afl=-11&day=1

Not sure what part of Wales you're in but both times could be up to 15 mins later
Extract a sunrise time for a date when you know what time you started generating and you should get a rough idea of how long after official sunrise you start generating.

Or wait till June & check meter of course

EricMears

We started getting clear sky around 4pm yesterday. Beautifully sunny evening but very little generation due to shallow panels, low angle of sun plus a bit of shading from a chimney (strings were set so that only half of panels affected by shade at same time).
Fabulously clear skies after dark - shame that panels don't react to starlight !
East Midlands weather forecast promised fog all morning. Luckily, Met Office had hung their seaweed upside down again and our clear sky continues.
Today's sunrise in London 06:45
adjustment for 1deg 22' W 5.5 minutes
Actual sunrise here 06:50
Generation started at 07:15 (albeit only 12 watts !) so guess I can say no generation for first half hour. No doubt Martyn in Wales will have a rather shorter 'dead time' from his SSE panels.
Now (10:40) up to 2.4kw (remember panels are only 17.5 deg). Wattson telling me I've got a surplus of almost 2KW so off to switch on washing machine.

larkim

don0301 wrote: »

16.4 kWh today

286.9 kWh for month :j

and as promised my figures

points to note:

Projected estimate for first year £2100-£2300

Projected return of Capital 5 yrs 9 days

:D:D

Just a minor question - what rate are you using for the export tariff? I was trying to check your workings (I'm an accountant, that's what I do!) - eg. Feb - 161.7 kWh generated. Divide 161.7 by £72.52 gives a rate of 44.85 per unit - deduct 41.3 from that leaves 3.5p per unit generated, which doesn't feel right.

It doesn't make a massive difference to your numbers, just curious!

(Not grumpy today!)

Matt

don0301

larkim wrote: »

Just a minor question - what rate are you using for the export tariff? I was trying to check your workings (I'm an accountant, that's what I do!) - eg. Feb - 161.7 kWh generated. Divide 161.7 by £72.52 gives a rate of 44.85 per unit - deduct 41.3 from that leaves 3.5p per unit generated, which doesn't feel right.

It doesn't make a massive difference to your numbers, just curious!

(Not grumpy today!)

Matt

Export tariff is 50% of 3.1p, 1.55p

Feb i generated 286.9 kWh

and it's 43.3p

not much of an accountant then

larkim

larkim wrote: »

I read on another site (or at least I think I did!) how to make the total consumption meter figure on an OWL "work" properly (or at least better than the normal setup).

I think it involved taking a splice out from the solar generation "brown" cable (i.e. the cable that you would normally measure your solar output on with an OWL) and somehow feeding both that cable (on which you know the "direction" of the electricity flow - it is always something to be deducted from your total consumption) as well as the normal mains flow through a second OWL clamp.

"Normal" OWL readings
1.5 solar meter with 1.0 demand = (-)0.5 net meter - but I want it to read 1.0 demand
1.5 solar meter with 2.0 demand = (+)0.5 net meter - but I want it to read 2.0 demand
(The issue is that the net meter doesn't show its +ve or -ve indicator (it can't), but that is the "real" position)

"Revised wiring" OWL readings
1.5 solar meter with 1.0 demand = -0.5 net usage PLUS new wiring 1.5 in the same clamp = 1.0 which equals the demand (which is the figure I'd like to know)
1.5 solar meter with 2.0 demand = 0.5 net usage PLUS new wiring 1.5 in the same clamp = 2.0 which (again) equals the demand figure.

I think that was how it was supposed to work. I don't know whether that is electrically feasible, but it would appear to give two "real" figures to work with (solar generated and household demand) which is what people (like me) with two OWLs are missing.

Hope someone with a better understanding of wiring can make sense of whether this works or not!

Matt

I posted this about a month ago as my understanding of someone's approach to getting a more valid net usage figure using a couple of Owl meters. No one responded, so I'm curious as to whether any of the technical minds here can tell me if its right or wrong!

Matt

Dave_Fowler

larkim wrote: »

I posted this about a month ago as my understanding of someone's approach to getting a more valid net usage figure using a couple of Owl meters. No one responded, so I'm curious as to whether any of the technical minds here can tell me if its right or wrong!

Matt

I think what you are saying is correct - provided you pass the solar gen wire the correct way through the current probe - otherwise you'd get 2xsolar + demand.

There may be practical problems with the standard Owl sensor. Mine only just takes the thick cable from the consumer unit and I would not be able to fit the extra wire through it.

Even if I were to get the larger diameter sensor, the lengths of wire available in my system prevent me from ever getting the wires through the same sensor without removing the outer sleeve from the 3 core cable. Not a job I recommend unless you know what you're doing and isolate the system first.

Dave F

EricMears

seagull09 wrote: »

On a different subject (and really the one of this thread!): anyone know of the most reliable meter for reading PV generation and exporting data to PC - preferably without having to leave computer running all the time? The OptiSmart looked good but currently not available. I don't really need to see consumption data, just generation would be handy.

For generation results, I'm happy to rely on our 'sunnyBoy' 4000TL inverter. I do actually have it connected via Bluetooth to my computer all the time but there's really no need to as the inverter itself stores several months worth of daily data and can download it's history every day or every few months whichever you ask. It doesn't show quite the same results as the official generation meter but it's only a few units out in six months so far better than any external 'clamp on' meter such as Wattson, Owl etc.

grahamc2003

seagull09 wrote: »

Well it's turned out rubbish here yet again, after a lovely clear night and a clear morning, it went dark and grey at about 10.45 this morning, just as the sun was coming round onto my panels. :wall:

And it's stayed like that. Annoyingly, just 30 or so miles to the east in Newtown Powys it's a lovely sunny day.

I shall be looking at those sunshine maps (thanks Martyn) for Feb and March on the Met Office site with great interest when they come out - because the mid-range March forecast for Wales is pretty grotty too.

On a different subject (and really the one of this thread!): anyone know of the most reliable meter for reading PV generation and exporting data to PC - preferably without having to leave computer running all the time? The OptiSmart looked good but currently not available. I don't really need to see consumption data, just generation would be handy.

I've got and eon monitor hooked up to the inverter output. It's quite accurate over a couple of hundred watts (it agrees with the inverter display very well), but below that it seems to read about double the inverter (surprisingly reasonably consistently). It is much more accurate than an owl, which I have hooked up to mains import (the usual set-up, i.e. consumption minus solar generation (with no negative sign if it's negative!)). The owl really is absolutely useless below about 250W, and any reading below that really means nothing at all. The eon monitor saves a month of data and can be downloaded to the pc, then manipulated with bugridden eon software.

What you really need for accurate generation data is a bluetooth module inside your inverter - sunnyboys have those as an option, perhaps worth chcking whether yours has too.