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

grahamc2003

pwllbwdr wrote: »

Thanks. Our system is 3.95kWp, we're in North Wales. It is SW facing, abt 35 degrees elevation. I reckon in summer it will come on stream quite early in the morning.

Oil hasn't dropped much in the last couple of years. Although the dollar oil price came down, the weak pound means that heating oil costs are still massive.

Consumption will undoubtedly vary from season to season, but a lot of the heat loss occurs when cooking is taking place, so consumption in summer daytime is still pretty high, especially if you set a timer to turn it down or off during the night.

I don't think anyone has made a heat pump AGA yet, but for the other question above, yes they do run off a standard 13A spur. They're continually on.

When you say 'continually on', do you mean the element is heating all the time with no thermostat? Sounds odd to me. When I looked into converting my AGA from oil to electricity, I think the only option then was nightime (i.e. E7) heating, a bit like a storage heater (in fact very much like an uncontrollable storage heater which you can cook on). That was a few years ago, but it was still very expensive even on cheap rates.

If it is on all the time, then the power is 220/7*24, which is 1.3kW. The problem with that is that it would take days to get up to temperature - are you sure it's on all the time, and therefore it only has a 1.3kW element? I'd expect something like the max possible on a 13A spur, which I expect is about 3kW (but you'd then be limited with whatever else is connected on the ring main).

We sometimes run ours (oil) for a couple of weeks at Christmas, but apart from that it's off - cooking and a warm kitchen for £100pm seemed a bit much for us. We never did run it in the summer - paying to have a too hot kitchen isn't the sort of thing I do.

If the electric Aga does cycle a 3kW heater, then of course, it won't match the solar output very well - a lower powered constantly on one would be better I suppose.

grahamc2003

John_Pierpoint wrote: »

Valentine's day - some how DW does not understand that this is much more exciting than red roses.

The manual helpfully talks about "closing" the external switches.
to turn on, (Then a "traffic light" array of LED's will explain what is happening (preferably leading to a constant green !)).
The turning off instructions are to reverse the switching on instructions!!
BUT I've got three such isolation switches.

So in which order do I turn them on/off ?
Does it matter if the panels are bathing in full sunshine with nowhere for the electricity to go ?

My electrician gave a bit of a demo of what to test on my system - nothing more than pressing the rcd then resetting it once every six months. He said no need to touch any other of the switches - they're just for those working on the system (little does he know I'll soon be nosing around). So it doesn't look like there's any important procedure to follow - but I'm not a sparky so don't take my word for it.
'Closing' means switching on.

pwllbwdr

grahamc2003 wrote: »

When you say 'continually on', do you mean the element is heating all the time with no thermostat? Sounds odd to me. When I looked into converting my AGA from oil to electricity, I think the only option then was nightime (i.e. E7) heating, a bit like a storage heater (in fact very much like an uncontrollable storage heater which you can cook on). That was a few years ago, but it was still very expensive even on cheap rates.

If it is on all the time, then the power is 220/7*24, which is 1.3kW. The problem with that is that it would take days to get up to temperature - are you sure it's on all the time, and therefore it only has a 1.3kW element? I'd expect something like the max possible on a 13A spur, which I expect is about 3kW (but you'd then be limited with whatever else is connected on the ring main).

We sometimes run ours (oil) for a couple of weeks at Christmas, but apart from that it's off - cooking and a warm kitchen for £100pm seemed a bit much for us. We never did run it in the summer - paying to have a too hot kitchen isn't the sort of thing I do.

If the electric Aga does cycle a 3kW heater, then of course, it won't match the solar output very well - a lower powered constantly on one would be better I suppose.

No - I said continually on to explain that it isn't a normal cooker needing to be heated up for each use. I'm pretty sure it is a thermostatically controlled load, not sure of the power draw when it is on.

The 13A ones are relatively recent - the older type of electric ones are economy 7 as you say, this is completely different.

I take what you say about any on/off thermostatic load not being a perfect match for a solar energy source, but the way I see it is that has to be viewed in the context of the alternative energy source being displaced.

If we start from the position that there is going to be an AGA and it is going to be on 24/7 (ours is), then provided the standard rate electricity isn't hugely more pricey than the oil (when taking into account the inefficient burner type), it seems to be to be a good option. Any transfer of energy source to the PV which is taking up PV gen which would otherwise be exported is a good thing, no? Provided that doesn't cause you to end up using peak rate electricity if you have a much cheaper alternative (i.e. gas). We don't.

One of the conversions includes a time/temperature controller which allows you to drop the temperature for certain parts of the day. If that was timed properly you could run the AGA on low overnight and then schedule its return to full temperature for a time you expected a good likelihood of solar generation. Not foolproof, but again it depends on the cost of the other energy source.

don0301

grahamc2003 wrote: »

My electrician gave a bit of a demo of what to test on my system - nothing more than pressing the rcd then resetting it once every six months. He said no need to touch any other of the switches - they're just for those working on the system (little does he know I'll soon be nosing around). So it doesn't look like there's any important procedure to follow - but I'm not a sparky so don't take my word for it.
'Closing' means switching on.

there's always 'good practice' but then there is always people like you too..

Martyn1981

John_Pierpoint wrote: »

Valentine's day - some how DW does not understand that this is much more exciting than red roses.

BUT I've got three such isolation switches.

So in which order do I turn them on/off ?
Does it matter if the panels are bathing in full sunshine with nowhere for the electricity to go ?

John, been digging further, regarding procedural order.

For fun, you can listen to a guy with a funny accent tell you what to do with an SMA:

http://www.youtube.com/watch?v=7Y4sEY6yKtQ

For Power One, the manual, page 49 has the same order, but then helpfully states that it doesn't matter!

The start-up procedure is as follows:
1) Set the external DC disconnect, if present, (for the photovoltaic panels) to ON
2) Set the external AC disconnect (for the grid) to ON.
There is no specific order for closing the two disconnects.

http://www.power-one.com/sites/power-one.com/files/manual4.2us_0.pdf

Doesn't look like you need to worry, unless you also have some 'bossy stickers'. If so play by the rules and keep your warranty safe.

Another fun day of flashing?

Mart.

John_Pierpoint

Thanks Mart,

This on-line manual pre-dates mine - no illustration of the blue tooth radio stuff. I wonder if that will interfere with the lap top communication to our router?
My paper manual is a subset of this North American manual, it has been created for the EU market and further afield.

Interestingly this original manual does mention agents in other countries but not UK. It does lapse into a foreign language at one point - Italian.
Lets hope its Italian influence does not mean it is like an Italian car: fast, clever and flash; but falls to bits sooner.

I kind of reasoned that turning off the AC should activate something inside the inverter that automatically turn off the DC, because the electricity now has nowhere to go and so it has:

To avoid any possible islanding operation, the Aurora inverter is provided
with an automatic disconnection protective system called Anti-Islanding.
The AURORA PVI-3.0/3.6/4.2-OUTD-US model is equipped with a state-of-the-art
anti-islanding protection system certified to the following standards and regulations:
• CSA-C22.2 N.107.1-01 UL Std N.1741

I wonder what one of these is in everyday English, presumably that is what I've got? :
On the AC output side an automatic magnetothermic switch should be inserted
between the Aurora inverter and the distribution grid

Do I need to have some rolls of black polythene and suitable clips for this
emergency turn off and access the inverter situation:

STEP 1 If the inverter is connected to the AC Grid (Fig. 15- “Terminal Block for AC Connection”– pos. "1", "2" and "3"), DISCONNECT the inverter from the AC Grid by opening the switch indicated as Part “D” in Fig. 9-“Electrical Connection Diagram”. Disconnect the DC side switch (integrated in the –S models, or externally provided).

STEP 2 Carefully cover all the photovoltaic panels using appropriate cover or perform the grid CONNECTION and/or DISCONNECTION operation during night hours.
Ensure that the no photovoltaic panel can provide energy during this operation.

I think I now know how the product makes the boast that it is not using mains juice over night. Rather like in a former life I had an involvement with a bulldozer: I hand cranked a Morris minor petrol engine, the petrol engine then cranked the bulldozer engine into action. I wonder how long this internal battery lasts:

STEP 1: Disconnect the inverter from the AC Grid using the AC disconnect switch shown as " Part "D" in Fig. 9 – " Connection Diagram".
STEP 2: Wait about 5 minutes to allow the internal capacitors to discharge (verify that the LEDs on the front panel are OFF).
STEP 3: Disconnect the High Voltage DC power line coming from the photovoltaic arrays using the appropriate switch (switch "C" of the Switch Box shown in Fig. 11 - "SB-01 - DC Switch Box Layout"). Turn the switch to the OFF position as shown on the silk print shown in Fig. 11 "SB-01" and LOCK as shown in Fig. "SB-02 – DC Switch Box/Safety Lock". This step completes the electrical disconnection of the inverter from the DC Switch Box.

[I have a different switch from the Aurora designed N.American one, so only if messing with the direct voltage switches is "doing it in the hours of darkness" or covering the panels required].

However this procedure might be an expensive PITA if it really needs a qualified electrician.

Inside the Aurora inverter there is a CR2032 lithium battery. When this battery is at end-of-life, a message will be shown in the display informing that the battery needs to be replaced.
The battery is visible after removing the Aurora inverter's front panel. Refer to section 3.3.2 for the procedures to remove the front panel.
To insert the new battery into the battery holder the battery needs to be slid at a 30° angle as shown in Fig 16, and when pushed in on insertion it should seat into the correct position within the holder.

WARNING: The replacement of this battery should be performed only by
trained personnel.

As well as the information that scrolls out on the display, that we identified and decoded in previous postings, there is other information/analysis that could be downloaded to our PC:
• Grid voltage
• Grid current
• Grid frequency
• Power transferred to the grid
• Voltage of photovoltaic array 1
• Current of photovoltaic array 1
• Voltage of photovoltaic array 2
• Current of photovoltaic array 2
• Heat sink temperature
• Serial number / Part number
• Manufacturing week
• Firmware revision code
• Daily energy
• Leakage current of the system
• Total energy
• Partial energy
• Mean grid voltage
• Insulation resistance
• Leakage current to ground
• Date, time

Plus

- CLOCK FAIL indicates clock malfunction; contact service
- BATTERY LOW
- SET TIME, appears the first time the unit is powered up or after the battery has been
replaced.
- FAN FAIL: contact service
- MEMORY FAIL: Data logging malfunction. Contact service.

Then available to the screen (by fiddling with the buttons) or to a service engineer/users laptop, we have:
Address
Display Set
Service
New Password
Cash
Time
Language
Vstart
Autotest
Alarm
Remote Control
UV Prot.time
MPPT scan EN/DIS
Scan Period

and the ability to extract statistics:

Lifetime
Partial
Today
Last 7 days
Last Month
Last 30 Days
Last 365 Days
User [defined] period

This could get really nerdy and addictive.On a lighter note, what do we think is the gender of an inverter - traditionally [unreliable and temperamental but loved] cars were female.

http://en.wikipedia.org/wiki/Genevieve_%28film%29

Anyway I caught he/she/it waking up this morning at 06:58.

It seems that a voltage of 200 Vdc acts as the alarm call and once a reliable
200 Vdc or greater is established off we go 22kWh since last Tuesday and by 07:15 in sunny Essex we were producing 37 Watts.
Now at 09:00 GMT we are achieving 2,222 Watts. [but with a SE orientation the sun is "square on" to the panels]

Fingers crossed for a record day for the 3.6 system.

http://www.power-one.com/sites/power...ual4.2us_0.pdf

sly_dog_jonah

Martyn1981 wrote: »

Anyone else noticing how the system outputs are steadily changing. Or am I the only truly sad soul here?

Further to my previous reply, I've been comparing when our system starts generating and stops generating. Our monitor logs output in 15min increments so I can see when the first/last non-zero outputs are each day. The following comparisons are between days where it was clear blue skies at sunrise and sunset. I've also added total generation (these were some of the best days around each date)

Date First energy Last Energy Total Generation (kWh)
18th Dec 0800 1545 8.03
2nd Feb 0745 1645 14.8
11th Feb 0730 1700 15.7
18th Feb [Cloudy morning] 1715 3.49 (cloud only cleared late on, included for the sunset time) 
19th Feb 0715 [Today]

We're SE facing we catch the sun as soon as it's above next door, this morning we were outputting 2.2kW before 9am (2.6kW as I write this). We lose direct sunlight aboard 3/4pm currently but still keep generating for an appreciable period afterwards.

grahamc2003

pwllbwdr wrote: »

No - I said continually on to explain that it isn't a normal cooker needing to be heated up for each use. I'm pretty sure it is a thermostatically controlled load, not sure of the power draw when it is on.

The 13A ones are relatively recent - the older type of electric ones are economy 7 as you say, this is completely different.

I take what you say about any on/off thermostatic load not being a perfect match for a solar energy source, but the way I see it is that has to be viewed in the context of the alternative energy source being displaced.

If we start from the position that there is going to be an AGA and it is going to be on 24/7 (ours is), then provided the standard rate electricity isn't hugely more pricey than the oil (when taking into account the inefficient burner type), it seems to be to be a good option. Any transfer of energy source to the PV which is taking up PV gen which would otherwise be exported is a good thing, no? Provided that doesn't cause you to end up using peak rate electricity if you have a much cheaper alternative (i.e. gas). We don't.

One of the conversions includes a time/temperature controller which allows you to drop the temperature for certain parts of the day. If that was timed properly you could run the AGA on low overnight and then schedule its return to full temperature for a time you expected a good likelihood of solar generation. Not foolproof, but again it depends on the cost of the other energy source.

If you want a rough estimate of the savings solar will give you with your setup, probably the easiest way is to do it graphically (a few years ago I would have easily calculated it analytically making reasonable assumptions - anyone care to have a bash?).

If you want to try it, get some graph paper, and plot time on the x axis and power on the y. Assume the average or typical output for your panels - probably a Gaussian (or normal or bell curve), start at 06:00 with 0kW, then plot to get your kWp (or 70/80% of it) at 12:00, then back down to zero at 18:00 (Just draw a bell shape hitting those points). Next, plot on top your AGA load, approximated by a 2.6kW load on half the time (say 1 hour on, one hour off, all through the day - so you get a superimposed square wave.

The graphs will show (roughly, under those assumptions) how your generation will cover your load, and the area under both the Aga load (the square wave) and the solar generation (the gaussian) will, give you the energy covered (in kWh), so simple to see how much that saves you (by multiplying by your cost/kWh).

From that basic approach, you can refine it to death - first refinement would be to estimate your background load (I'd assumes 100W in my case), and offset the aga load by that.

(BTW to preempt responses from various quarters, this is an estimate, not an exact science, and it won't produce an exact answer, but it wil produce an indication of likely savings - there are thousands of refinements can be made to get a close approximation to the answer.)

thenudeone

pwllbwdr wrote: »

One thing I'm considering is converting our AGA to electricity. The conversions run off a 13A supply, so not the economy 7 thermal store ones.

But the conversions will no longer provide domestic hot water. Another extra cost to factor in.

Plus you are then 100% dependant on electricity. If you are in a very rural area subject to more than average power cuts, the ability to have a constant heat source even when its -15C outside and the electricity is off, could be worth having.

pwllbwdr

thenudeone wrote: »

But the conversions will no longer provide domestic hot water. Another extra cost to factor in.

Plus you are then 100% dependant on electricity. If you are in a very rural area subject to more than average power cuts, the ability to have a constant heat source even when its -15C outside and the electricity is off, could be worth having.

Thanks. We don't have it making hot water - no point as the CH boiler is oil also and is probably more efficient than the AGA burner.

True about us then being dependant on electricity. We are rural and do have power cuts occasionally. We have a solid fuel stove in the sitting room and this heats virtually the whole house when we fire it up fully. It has been on continually for the last few weeks and the CH has hardly fired up.

Being without cooking if there is a protracted power cut is a valid point, and about the only real downside I can see.