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

anitainjune

Sorry so many discussions here I got bogged down. I think I understand that I should use energy when I'm generating but, we've been on E7 for years and used energy overnight. Its still cheaper by nearly 7p per unit to do this and we've been told it will cost us to change our meter back to an ordniary tarrif. So in winter are we not still better to use washer/dishwasher etc over night?

Brian99_2

cazarol wrote: »

I know it is a 4 kw system, panels are east and west facing (either side of the roof) .

With east and west roofs, it is essential to have a special inverter,which processes the two sides separately. Hopefully your installer knew this and wired them right ?

sly_dog_jonah

gary_e wrote: »

I am being offered free panels but my roof faces west and east. What benefit would I get? I have heard that the panels need to face south, is someone just getting trying to get me to say yes just to hit his targets?

Please advise

You'd get some free electricity when the sun is in the west and east, but not very much in the middle of the day.

If the house isn't normally occupied in the day, this east-west factor may be to your advantage as the free electricity may overlap with your morning and late afternoon usage. The peak power would be proportional to the size of each array, and would max out at under 50% of the total capacity as a rough rule of thumb on a perfectly clear sunny day (because the sun can only shine directly on one orientation of panels at a time).

If the house is normally occupied during the day, a south facing roof is better as your peak power output would be greater and you'd be more likely to be able to run high-power applicances such as dishwasher's and washing machines without using any power from the grid. These can of course be timed to come on, but are best started manually when there's no sign of clouds.

Beyond the electricity savings, there's no other benefit to you. Ask yourself what's in it for the company offering this 'free' deal.

teggyboymoll

:T

larkim wrote: »

Don't be daft, surely you save more if you are with the most expensive electricity supplier!!



Matt

The FIT tarrif is the same so if you are with an expensive supplier you are paying dear when not generating so starting out with a cheaper s
supplier makes more sense to me!!:rotfl:

sly_dog_jonah

anitainjune wrote: »

Sorry so many discussions here I got bogged down. I think I understand that I should use energy when I'm generating but, we've been on E7 for years and used energy overnight. Its still cheaper by nearly 7p per unit to do this and we've been told it will cost us to change our meter back to an ordniary tarrif. So in winter are we not still better to use washer/dishwasher etc over night?

The way to maximise electricity cost savings with E7 is as you correctly put it, to maximise your usage during those 7 hours at night, and minimise it during the day.

Adding a solar system into the mix effectively changes the 'cost' of electricity during the day, because at least some if not all of your house's electricity needs will be met by the panels in good weather, for some parts of the day. This means that sometimes your (import) electricity meter(s) will not be increasing, as the power from the panels will be sufficient to power your home.

On some days though, irrespective of season, you'll make hardly any electricity. Other days, you may make 10x as much power as on a rubbish day and depending on the size of the system could be generating more than 3kW at the optimum time of day. That's enough to have multiple appliances running at the same time, but on less sunny days it's better to spread out the appliance start times to ensure you aren't importing electricity to make up for what the panels can't provide (eg when an evil cloud sails by).

In summary then, on a good day you can either run your appliances:

(i) for free (or nearly free) during the daytime if the panels are kicking out a decent amount of power
(ii) cheaply at night (during E7 hours) using E7 rate electricity
(iii) expensively during the day on 'daytime' rate electricity (but your panels might reduce the effective cost even on an overcast day, as they will provide some power - about 10% of what they would do on a perfect blue-sky day). When it's dark but outside of E7 times, you're burning cash at the highest rate when you use electricity.

To maximise your savings, try to use electricity when (i) applies first, then (ii) and only when you have to (iii).

John_Pierpoint

Brian99 wrote: »

With east and west roofs, it is essential to have a special inverter,which processes the two sides separately. Hopefully your installer knew this and wired them right ?

My type of inverter would do the job - see below. I have 4 input wires to the inverter (and one fattish circular lead going out to the mains)

Martyn1981

anitainjune wrote: »

Sorry so many discussions here I got bogged down. I think I understand that I should use energy when I'm generating but, we've been on E7 for years and used energy overnight. Its still cheaper by nearly 7p per unit to do this and we've been told it will cost us to change our meter back to an ordniary tarrif. So in winter are we not still better to use washer/dishwasher etc over night?

Afternoon. yep, lots of chats going on. Nice to see the thread so busy.

Big question for you, is it still worth having E7 now you have PV? If it is (probably essential if you have electric heating) then what and when to use will get a bit tricky for you, especially in winter.

Do you have a medium or bigger system, i.e. does / can it generate 2kW+ for several hours? If so, then it could power the washing machine, dishwasher etc completely free on a good day. However, if it's not big enough, or not generating enough due to low sun angle in winter, then it may only supply half the power needed, which depending on your daytime tariff, may balance out with E7.

Sorry to be so difficult, but it does get tricky for you, especially in winter. PV obviously contributes whenever on, but if you switch a big load on, that could be done under E7, then you need to think how much of said load the PV will cover. Does that make any sense (at all)?

Might be useful to get (if you don't already) a monitor that relays the TGM input, so you have a real time idea of what you are generating, which will help you decide whether to run a heavy load or not.

Mart.

Edit: More simply, ignore this post and read Sly Dog's above - it's better!

John_Pierpoint

My new system has an inverter created by these people:

http://www.power-one.com/renewable-energy/products/solar/string-inverters/aurora-uno/pvi-30-pvi-36-pvi-42/series

My inverter is model PVI – 3.6 I]PhotoVoltaicInverter with a nominal output of 3.6 kW[/I
It has an input of two strings of 9 panels on one roof plane

It has a West Coast of America parentage and churns out masses of information on its liquid crystal display on the front. I have spent 30 minutes trying to write down the cycle of over a dozen displays. [This means that the numbers won’t add up as they are not contemporaneous]

In what follows the inverter speaks in normal script and I attempt to translate and understand in Italic.

Please comment, expand and correct me, where I’ve “got the wrong end of the stick”:

Inverter: OK
.............
Friday 17 February 2012 11:45
Type: OUT D
...............
E – tot..........15kWh [Probably the two and a half day’s generation so far]
P/N...............- 3G97 – [Presumably Part Number ?]
...............
S/N...............1234567 [Serial number]
FW Rel..........C.0.2.2. [Firm Ware version ie the program on the chip that controls it.]
..................
E day ...........3.1 kWh [The output today so far.]
$ day.............1.5 EUR [Profit today - Oh God it thinks all of Europe is on the Euro].
......................
P OUT..............556W [current rate of output – half a bar on an electric fire]
T INV ..............27.5 C [Temperature of the inverter – that will cut the store room damp]
.......................
Ppk ...............3468 W [Could this be the highest throughput rate to date?]
Ppk.day..........2525.W [Could this be the highest throughput rate today so far?]
.............
Vgrid..............248 [The momentary voltage in the grid]
Vgrid Avg......249 [An average figure over some period of time ?]
...................
I grid...............1.5A [Is that an output figure?]
F grid.............50.1 hz [The frequency of the grid]
.....................
Vin1...........233 V [What is available from string one]
I in 1...........1.4 A [What is available from string one]
...................
V in 2.........233 V [What is available from string two]
I in 2.........1.4 A [What is available from string two]
..................
P in 1.........186 W [The watts from string one]
P in 2.........183 W [The watts from string two]

R iso... 20 MΩ [Proof that the insulation inside the inverter has not perished]
I leak.... 0 mA [ditto]


Any further thoughts?

Bezique

Not sure if this has been said already but we have an Ecosavers Meter (Amazon £14.99). You set the cost of your electric and plug it into the wall before the appliance and it tells you how much the electricity used has cost, time used for, how many kWh and various other info. We've used it to work out the cost of running items for 24 hrs i.e central heating boiler, fridge/freezer, phones, Hard drive recorder or for set things i.e. Washing machine (60% wash uses nearly 2 1/2 x more than a 40% wash), Kettle min 2 cups and full 6 cups (oddly uses 4 x more for 6 cups than 2 cups!). Have to write things down before you switch off power but very interesting and makes you realise exactly what uses the most power.

Although we have Solar PV we use Economy 7 so still try to run things at night as unless very sunny day in summer we calculate we are using all that we produce (Hubby keeps snakes and tortoises so 1 room heated to 80 degrees:o). Did calculate that we are only saving a small amount on E7 but still worth it at the moment as long as I use as much at night as possible. The deemed export amount we recd last yr was approx £50 = 400 units of leccy at our daytime rate so an extra £50 in our pocket as we have already used it.

We have a 3.33kWh system on a SSE facing roof. Estimated annual output of 2847 kWh (which would be 25% of our annual electric) but we actually got 3212 kWh. Recd £1421.31 in FIT payments. We are in Sussex on the coast. Best daily reading 21kWh. Have found that we recd less than estimated in Jan, Feb, Nov & Dec but more in the other months. Any shading however slight (1 weedy piece of fuchsia) does make a lot of difference.

Brian99_2

Martyn1981 wrote: »

Hopefully then we can check to see if it has MPPT.

Edit: apologies for the abbreviation, multi point power tracking, allowing two different feeds that don't effect each other.

Mart.

Sorry.... this really confused me so I googled MPPT and it seems to be MAXIMUM power point tracking, for one string.

So an E-W roof will need a DUAL MPPT inverter.

Does this make sense ?