Solar Power - Definitely Green but is it affordable

007apm

As was the guidance from many forums and web articles, it is a good idea to monitor the meters for the first  few weeks to make sure nothing is amiss.  I have however found a likely fault in the installation.  We have 2 fuse boxes, one for upstairs and one for downstairs.  The downstairs fuse box has a new fuse for 'Solar' but the upstairs one has not been changed.  Given that we have some TVs, a games console and some hair dryers upstairs, I am hoping that connecting upstairs to solar will then use the battery / direct solar feed and reduce our grid dependency even further and save on grid imports!  I'm expecting the engineer tomorrow and will report back in a few days.

QrizB

That isn't how it works, unless you've got two separate meters and pay two separate bills, one per floor.

Spies

You can have 2 consumer units but ultimately they will be fed off one meter, doesn't matter which CU the solar is connected to, they will be connected and electricity can flow either way... 

007apm

The installer is sending an engineer today having been provide with the information and seems to agree that something is wrong.  We wave one meter, but if it has been wired correctly, I don't get the fuse in one box and not the other.  There again, I don't see the point of the fuse at all. As @Spies and @QrizB suggest, the solar + battery + grid should be managed by the device and should be a single feed to both consumer units.  Thanks for your contributions...

QrizB

The fuse (or more likely circuit breaker) is there to reduce the chance of your house burning down in the event of a fault. Every circuit in your house should have one.

007apm

Thanks, the fuse is for the inverter, I'm told but should not be in the normal consumer unit and is probably what was causing the supply to trip.  @Spies was quite right, however the installer had for some reason put the sensor inside the downstairs consumer unit monitoring only downstair usage.  The correct place for the sensor clamp is on the feed in to the house from the meter.  The chief sparky is back today to resolve the issues so fair play to the supplier, but the increased demand for solar / other renewables is causing installers to use subcontractors where the quality of work is variable.  Last week's usage was as follows:

W/E 11/5/22	Average	Min	Max
Used	12.5	9.9	17.4
Grid	2.26	1.1	3.4
Generated	23.5	9.7	33.5
SEG	13.3	0.1	22.7

Grid usage from the grid was higher than I think it should be. Our expectation for the system is 23KWh/Day in May and we are bang on target. 

007apm

Post script:  Our average daily gas usage was about 12.7 KWh / day which makes us net neutral which is an important milestone for our younger family members and friends.

007apm

w/e 19/5           Week         Day

KWh                 Total          Average   Min       Max

Used                 97.1          13.87         9.6        18.4

Grid                   6.2            0.885         0.3        2.4

Generated        185.7        26.52         15.7      35.6

SEG                  94.8          13.54          0.6       22.2

Net  energy neutral because we used 72KWh gas in the same period.

007apm

I hope that this is useful to anyone considering investing in solar + batteries.  May in theory should be the best generation month where we live in Bedfordshire and our expectation was that we should generate 726 KWh in our first full month of operation and we achieved 97.5% of target. Some weather research suggested that May 22 wasn't great with 7 rain days, 18 cloudy days and 6 sunny days which would suggest that our future hopes for the system are quite achievable allowing for the vagaries of our British weather.

KWh	Total	Average	Min	Max
Used	387.8	12.51	8.7	18.4
Grid	40	1.29	0.2	3.8
Generated	707.8	22.83	9.7	42.4
SEG	360	11.61	0.1	26.1

Our grid usage was higher than it should have been because of a wiring fault which was corrected mid month but we used 90% of our own energy and contributed a net 320KWh to the grid. With a gas usage of 380KWh we were a net energy consumer using about 60KWh in the month.  The final score is that we reduced the carbon foot print of the house to 7.8% of what it would have been without the micro generation system.  

007apm

We based our design on a web model that gave an expected average yield for our system on a month by month basis and at one point this month the model and real life actually matched!  Given real life and UK weather this must of course be a fluke, but great June weather means that the system is out performing expectation.

W/E 22Jun Week     Day

KWh           Total      Average     Min      Max

Used            61            8.71         6.3        13.1

Grid               3             0.43         0.2          0.6

Generated 211.9        30.27         6.9        39.2

SEG          153.9        21.98           0         30.5

Our biggest issue is that we can't claim SEG payments because our supplier requires a DNO authorising our supply to the grid.  I had assumed that this needed to be done (6KWP system) prior to installation but am not advised that this is no longer the case and that there is a backlog.  Our new supplier Octopus have been most helpful, alas our outgoing supplier Scottish Power still appear not to understand the needs of customers who install Solar PV.  Once we get this DNO we should be able to keep our electricity costs to an absolute minimum.