Moving into 2yo House With Preinstalled Solar Panels

Frank_Rizzo

Frank_Rizzo

Frank_Rizzo

Associate
Joined
18 Mar 2003
Posts
1,138
Been in this house two months now and finally getting around to the loft area! I have a few questions about the solar panels.

Specs
Technolgy Type: Solar Photovoltaic
Solar Meter: Rayleigh RIHXE12R
Smart (Dumbed) Meter: Aclara SGC1311
Total Installed Capacity: 1.25 kW
Installation Type: Standalone
Primary Energy Source: DNO
Inverter: Solis Mini Single Phase Invertor

Starting in the loft I can see that the inverter seems to be working correctly. There is a red led and a green led which are both static on. The manual says that means there is dc power, and the invertor is operating correctly respectively.

Under the stairs is the solar generation meter. This is a Rayleigh RIHXE12R and there is a worrying red led on it. It seems to be on continually for 5 seconds then go off for a quarter of a second and repeats. I can not see anything as to what the red led means in the datasheet or user manual, however on some sites it does say 'Red light to show no current'. Does that mean this is not functioning?

Meter Readings
The meter readings when we moved in were:

Rayleigh
Import: 2750.23
Export: 23.06

Smart (Dumbed) Meter
Import: 2490

This is a 4 bed house that had 2 adults staying there during those first 2 years. Thus the average figures per year are 1375 Imp, 11.5 Exp, 1245 Imp for the above meters

We have been in for 71 days and in that time our usage is:

Rayleigh
Import: 102.96
Export: 2.44

Smart (Dumbed) Meter
Import: 700

Why has the smart meter risen 700 whilst the solar meter (import) has only risen 103?

Multiplying those figures 365 and dividing by 71 gives average figures per year (I know, should adjust for summer and things) of 529.30 Imp, 12.54 Exp, 3598.60 Imp

That seems odd. The solar meter is saying we will use half as much as the previous occupants but the export will be just about the same. However, the smart meter is 3x greater than the previous occupants!

OK, we do work from home and there are a few machines here and the previous occupants did not work from home but these figures just don't seem right.

---

I just checked the figures after an hour and a half (15:20 to 16:50, clear sky, in the south west). The Rayleigh Import has risen 0.13 kW, the Rayleigh Export has not changed and the Smart Meter has risen 1 kW (although there are no decimal places showing so could be rounded up?)

What's going on here?
 
Flashing red LED will just show consumption.

Is it not just because you're using the energy you're generating, thats why theres hardly any export?

Presumably the house was empty a while before you moved in which would explain the export being higher.

It's also winter, so solar energy is going to be a lot less than say the middle of July.
 
The aclara meter is your DNO incoming main, so showing what you are using from the grid. If you press the B button (lower one) and cycle to total active export it will show you how much has left your property from your solar generation.

The Rayleigh meter will only show you generation from your solar array and the static red light with short blip is showing limited generation (blip every 1000 Impulse / KWh), this time of year that's to be expected as generation will be at its lowest. Ignore the export on this meter it means nothing

It will be very difficult to work out your generation and usage at the moment as you will be lucky to be generating more than a few kw's.
 
Last edited:
How many panels do you have and what rating are the panels? 1.25kw is a fairly small installation and that rating is the max output (so on a super clear summers day with direct sunlight).
 
Thanks for the replies.

There is no export on the B button. Pressing it cycles between these 5 displays only:

Mode
Boot
WAN
IOU
IMPORT

There are 5 panels. The install certificate says 1.25kW Total Installed Capacity, 1.25kW Declared Net Capacity, Estimated Annual Generation 1.10 kW Does that mean 1.10kW per panel or for all 5?

How can I tell if the electricity powering the house in the day is being supplied by solar, the grid or a mix of both? I was expecting somekind of display or reading for that e.g. 100% grid at midnight, 20% grid at midday.

Does it need an annual maintenance?

What about cleaning?
 
Ah sorry the A button should give you EXPORT.

The 1.25kwh will be the max rating of all the panels so combined production at max output.

The aclara meter should have a symbol that comes up when you are exporting power (not using what you generate) without the In Home Display functioning (as it's now a dumb meter it won't work) you cannot tell what you are using.

The owner of the panels (if it's a rent a roof installation) should take care of any maintenance and regular inspections of the equipment as it's not yours. Normally it's part of the particulars you obtain when having them installed.

Not knowing your install it's difficult to say for sure but you need to know if it's rent a roof or if you own the panels.
 
Nothing happens when I press A.

We own the panels. They are fitted as standard on all properties on this development.

Let's go back to the red lights. On the Aclara the led is off for about five seconds and then blips red briefly. IMO that's good.

But on the Rayleigh I think this is at fault. The red led is on constantly for five seconds and then blips off briefly then on for five seconds and repeat. According to some resources: "Red light to show no current" so to me that means no current is flowing through the Rayleigh so the panels may not be working.

Also on the Rayleigh is an Import / Export display. This alternates

Code 000 = Import and that was 2855.75 kW
Code 010 = Export and that was 25.53 kW

I can not believe, that in 2 years of use this solar array has only exported 25.53 kW. Sure if it's in use in the day, then it's not exporting but is being consumed local. But the previous occupiers must have been away for quite a few days, and they did not work at home, so surely there would be more than 25.53kW of export? Even at 20% of peak capactity that equates to just 102 hours within 2 years.
 
Frank_Rizzo said:
Nothing happens when I press A.
odd not sure why that does nothing..
We own the panels. They are fitted as standard on all properties on this development.

Let's go back to the red lights. On the Aclara the led is off for about five seconds and then blips red briefly. IMO that's good.
as it should be
But on the Rayleigh I think this is at fault. The red led is on constantly for five seconds and then blips off briefly then on for five seconds and repeat. According to some resources: "Red light to show no current" so to me that means no current is flowing through the Rayleigh so the panels may not be working.
the meter is working correctly as the light will stay on and only blink every 1000 impulse/kWh as level of generation is low at the moment the blink is slow

Also on the Rayleigh is an Import / Export display. This alternates

Code 000 = Import and that was 2855.75 kW
Code 010 = Export and that was 25.53 kW

I can not believe, that in 2 years of use this solar array has only exported 25.53 kW. Sure if it's in use in the day, then it's not exporting but is being consumed local. But the previous occupiers must have been away for quite a few days, and they did not work at home, so surely there would be more than 25.53kW of export? Even at 20% of peak capactity that equates to just 102 hours within 2 years.
Click to expand...
ignore the export on this meter as all it refers to is conversion loss from DC to AC. The meter import is the amount generated that you can use
 
Last edited:
A 1.25kW solar system is going to generate very little power especially at this time of year in the UK.

I have an 8.2kW array further south than the UK, today was a rainy/cloudy day and it only generated 2.69kWh. Your system is 15% of the size of mine...

I imagine the "export" register on your solar production meter is simply showing power that the inverter has pulled from the grid when it's asleep and the panels are not producing.
 
How did you find out you were generating 2.69kWh? That's what I am trying to find out: someway of showing what percentage of solar was being used from total consumption, or in my case how do I even know if it's generating anything at all?

If it can only generate 1.1 peak and ~0.4 at this time of year then what is the point in the developers installing them from new? Is this just a scam to appease green councillors who would turn down planning applications for these sites?

Lets look at figures. If at best I am only getting 0.4kWh at this time of year for say 5 hrs, and 1.1kWh for 10 hrs in the summer, and assumming 66% of days have sufficient sunlight to equal or exceed those figures then I make that 1560kWh generated per year. As I am paying 14.37p per kWh that means the panels could be saving me a max of £224 per year. From what I gather maintenance can range from £100 to £200 per year. At the lower end that could make a saving of £124 per year and that seems hardly worth it.

One other point. We have had a couple of power cuts. I believe the whole system shuts down if the inverter does not get any mains feed to it; it can't self power itself from the panels. Are there any models that can self power themselves, or have a UPS built in?
 
When I was using solar load controllers and inverters they both ran off the 12-30V supplied by my generation equipment. No mains involved, we were outdoors!

Note that inverters specifically take DC and turn it into AC. Shouldn't need mains. Whereas a load controller miiiight? But again shouldn't by design.
 
W
Frank_Rizzo said:
How did you find out you were generating 2.69kWh? That's what I am trying to find out: someway of showing what percentage of solar was being used from total consumption, or in my case how do I even know if it's generating anything at all?

If it can only generate 1.1 peak and ~0.4 at this time of year then what is the point in the developers installing them from new? Is this just a scam to appease green councillors who would turn down planning applications for these sites?

Lets look at figures. If at best I am only getting 0.4kWh at this time of year for say 5 hrs, and 1.1kWh for 10 hrs in the summer, and assumming 66% of days have sufficient sunlight to equal or exceed those figures then I make that 1560kWh generated per year. As I am paying 14.37p per kWh that means the panels could be saving me a max of £224 per year. From what I gather maintenance can range from £100 to £200 per year. At the lower end that could make a saving of £124 per year and that seems hardly worth it.

One other point. We have had a couple of power cuts. I believe the whole system shuts down if the inverter does not get any mains feed to it; it can't self power itself from the panels. Are there any models that can self power themselves, or have a UPS built in?
Click to expand...
Without knowing your equipment it would be very difficult to say anything about your hardware.

The installation you have will be the minimum requirement the builders had to install to meet requirements set out by the local councils building authority.
 
Frank_Rizzo said:
How did you find out you were generating 2.69kWh? That's what I am trying to find out: someway of showing what percentage of solar was being used from total consumption, or in my case how do I even know if it's generating anything at all?
Click to expand...

Because I have a SolarEdge inverter which is connected to the internet and reports the data. Incidentally on a sunny day at this time of year I generate 32-33kWh and over 40kWh at the height of summer.

If it can only generate 1.1 peak and ~0.4 at this time of year then what is the point in the developers installing them from new? Is this just a scam to appease green councillors who would turn down planning applications for these sites?

Lets look at figures. If at best I am only getting 0.4kWh at this time of year for say 5 hrs, and 1.1kWh for 10 hrs in the summer, and assumming 66% of days have sufficient sunlight to equal or exceed those figures then I make that 1560kWh generated per year. As I am paying 14.37p per kWh that means the panels could be saving me a max of £224 per year. From what I gather maintenance can range from £100 to £200 per year. At the lower end that could make a saving of £124 per year and that seems hardly worth it.
Click to expand...

It's a tiny system, the point is that it seems to be working fine but it isn't going to generate much electricity. At least you didn't pay to have it installed.

It sounds like you need to switch energy supplier as 14p/kWh is expensive.

No idea what maintenance you are referring to unless you are budgeting for an inverter replacement in the future?

One other point. We have had a couple of power cuts. I believe the whole system shuts down if the inverter does not get any mains feed to it; it can't self power itself from the panels. Are there any models that can self power themselves, or have a UPS built in?
Click to expand...

Solar inverters are grid tied for a reason, they have to shut down when the power goes out so there's no risk of them back feeding power and surprising a utility worker who is expecting the power to be off. The only way to use a solar system in a power outage is with a home battery and a gateway that physically isolates the house from the grid when the power goes out.
 
You do not need any form of maintenance the panels themselves will be self cleaning. If you are paying for maintenance then you are wasting your money.
 
Doobedoo - I don't have any maintenance contract with this. I was just enquiring if it did need maintaing - not just the panels but the complete system. From prices I have seen online maintenance ranges from £100 to £200+

OllyM - 40kW ! You can power the whole street for that. Are you using all that power or selling it?

14.37p is below the average for this area. It will do for now. And there are other reasons for going with a supplier rather than just unit rate.

I see the point about avoiding feeding back to the grid in a power cut. But there must be a way of having a private circuit without the grid e.g. outbuildings that have no grid connection.

----

It's a wonderful sunny day here in the SW so I did an experiment. I ran half the lights, tv, and all computing devices from 12:15 to 15:15 and noted the meter readings.

First the estimated power draw:

3x PCs 375W (inc screens)
1 rack server 155W
1 laptop 60W (inc external screen)
14 x 5W LED lights 70W
TV and box 50W
(smaller stuff: dect phone, router, central heating, clocks, media unit) 20W

I make that 730W per hour and over 3 hours 2.2kW total.

The Rayleigh Meter
Import display 2863.62 - 2860.86 = 2.76kW
Export display 25.55 - 25.55 = 0kW

The Alcara Meter (Grid)
Import 3209 - 3209 = 0kW

The Alcara does not use decimal places so in theory it could have registered 0 to 1.99 depending on how they do the rounding. But it's certainly not used 2.76kW as the Rayleigh box is indicating. That sounds fair to me. I guess I need to run the same test at midnight tonight :D, to see if 2.76kW is actually being used

Here's some pics of the panels and spec sheets if anyone is interested.

sp1.jpg


pv1.jpg


pv2.jpg
 
Last edited:
Frank_Rizzo said:
OllyM - 40kW ! You can power the whole street for that. Are you using all that power or selling it?
Click to expand...

We have net metering across a 12 month period here so anything exported to the grid just offsets future usage from the grid. On hot summer days I can easily burn 50kWh+ a day running the A/C.

It definitely sounds like your solar system is working perfectly. Your production meter "import" display is showing your solar production, ignore the "export" as it's clearly just energy that has flown the other way through the meter to keep the inverter powered when the sun isn't shining.
 
You must log in or register to reply here.
Back
Top Bottom