Rent-a-roof Solar, batteries and EV charging

Scrib0101

Reed_Richards said:

If you have a smart meter it should tell you what you actually do export.  If you get a battery then that will also have the capability to export and some people make use of this, charging their batteries when electricity is cheap and then exporting it again when they can get a higher rate for export.  You won't be able to do this because there is no way to distinguish export from your solar panels from export from your battery.  I presume your rent-a-roof company fear that you might be tempted to want to do this if you get a battery and this would upset the applecart of their deemed export payments.  

I have a SMETS 1 meter and cannot see anywhere on it that shows an export. As you pointed out it would be problematic if I also exported from batteries. Which is why I decided on Economy 7 as there is no feed in tariff with that and I will not export anything from batteries. It then allows me to:

At midnight switch to primary feed grid and charge batteries

7AM change to Solar as primary feed then batteries as secondary, grid as backup which really would only be needed if demand is higher than solar and batteries inverters can supply.

Then again at midnight back to grid feed.

Rinse and repeat each day.

Depending on time of year and amount of sunlight the amount of power in to batteries will go up or down. Even so a 6kWh inverter can easily charge 24kWh of batteries in 7 hours, should do it in 4 hours. I had considered the import and export from batteries but the amount of messing about with tariffs simply was not worth it.

Reed_Richards

I have a SMETS 2 meter which makes the export reading blindingly obvious by showing the export reading immediately after the import reading.  I'm not sure if all SMETS 1 meters can do export but if you identify the make and model somebody will doubtless be able to tell us.

I don't know if my inverter/battery combo is particularly bad at this but when there is a sudden increase in demand and there isn't enough solar to manage alone, it can take up to 10 seconds for my battery to ramp up to meet the demand.  So although I can get away with using very little day rate electricity in summer, it's never completely zero for a day.  The other side of the coin is that when the battery is supplying power and the demand ceases then it will export for a few seconds whilst ramping down its output.  So your battery will export a little, even though you don't want it to.  But the amount should be small to insignificant compared to your solar export.

mmmmikey

Reed_Richards said:

I have a SMETS 2 meter which makes the export reading blindingly obvious by showing the export reading immediately after the import reading.  I'm not sure if all SMETS 1 meters can do export but if you identify the make and model somebody will doubtless be able to tell us.

I don't know if my inverter/battery combo is particularly bad at this but when there is a sudden increase in demand and there isn't enough solar to manage alone, it can take up to 10 seconds for my battery to ramp up to meet the demand.  So although I can get away with using very little day rate electricity in summer, it's never completely zero for a day.  The other side of the coin is that when the battery is supplying power and the demand ceases then it will export for a few seconds whilst ramping down its output.  So your battery will export a little, even though you don't want it to.  But the amount should be small to insignificant compared to your solar export.

Hi @Reed_Richards good point, my system is much the same, there are various switching delays, as you say small to insignificant but definitely measurable and there. I think it's due (in my case at least) to a combination of the accuracy of the current clamps at low power and also the switching thresholds. 

Scrib0101

Reed_Richards said:

I don't know if my inverter/battery combo is particularly bad at this but when there is a sudden increase in demand and there isn't enough solar to manage alone, it can take up to 10 seconds for my battery to ramp up to meet the demand.  So although I can get away with using very little day rate electricity in summer, it's never completely zero for a day.  The other side of the coin is that when the battery is supplying power and the demand ceases then it will export for a few seconds whilst ramping down its output.  So your battery will export a little, even though you don't want it to.  But the amount should be small to insignificant compared to your solar export.

I was not expecting to get to 100% usage from economy 7, I was aiming at high 90%. I was not aware of the slight delay and as such may pull some form grid or feed to grid as batteries ramp up or down. As you say it is likely to be a small amount but useful information none the less.

Welsh_Rarebit

I also have a rent a roof Solar panel installation. I asked the suppliers about installing storage batteries and their 'stock' answer was that I was not allowed to connect anything to the existing solar panel installation. 

My contract also makes no mention of EV's or storage batteries.

Several responses have suggested purchasing the panels from the supplier, and the contract has a table of costs for this. My panels were installed 9 years ago and the price to purchase them now is more than it would cost to install new ones as panel prices these days are either the same or less as they were 9 years ago.

Lastly, I wasn't aware that I wasn't supposed to charge an EV - we've had an EV for 2 years and ALWAYS charge during the day - especially if the sun is shining and the panels are providing half the electric for free. I've had no contact from the installers enquiring why their feed in payments have reduced?

matt_drummer

Welsh_Rarebit said:

I also have a rent a roof Solar panel installation. I asked the suppliers about installing storage batteries and their 'stock' answer was that I was not allowed to connect anything to the existing solar panel installation. 

My contract also makes no mention of EV's or storage batteries.

Several responses have suggested purchasing the panels from the supplier, and the contract has a table of costs for this. My panels were installed 9 years ago and the price to purchase them now is more than it would cost to install new ones as panel prices these days are either the same or less as they were 9 years ago.

Lastly, I wasn't aware that I wasn't supposed to charge an EV - we've had an EV for 2 years and ALWAYS charge during the day - especially if the sun is shining and the panels are providing half the electric for free. I've had no contact from the installers enquiring why their feed in payments have reduced?

The installation on your roof is worth more than a new installation as it still has 11 years of FIT payments left to come.

You don't get FIT payments on new installations, the scheme stopped in 2019.

You can charge your car as much as you want, you are allowed to use as much of the solar generation as you like.

The amount of solar generation you consume has no bearing on the owners income. You can use 100% of what is generated and the panel owners still get the same income whilst you are on deemed export.

What you can't do is fit batteries. You'll then want a smart meter, if you don't already have one, and an export MPAN. That then opens your installation to the loss of the deemed export. That doesn't mean you would do it but it is one step closer to a loss of income to the panel owners, they won't want the trouble or the risk because once you have gone onto metered export you can't go straight back to deemed export. It will be a mess and and inconvenience that the panel owners don't need. Their income is safe at the moment and they won't want to change that.

I bet the contract says that you are not allowed to make any modifications to the installation? That is the part that prevents you installing battery storage. EV's don't need to be mentioned as they are not connected in any way to the solar panel installation in the same way that none of your other electrically operated equipment is.

Whoever had the panels installed benefitted from a free installation and the opportunity to consume as much of the generated electricity as they wished.

The only condition is that you can't treat the installation as your own. Not something I would have done but it is a fair and clear deal and there is nothing to complain about.

Welsh_Rarebit

I DO have a Smart Meter and MPAN's (whatever they are) for both Electric and Gas.  If I simply use excess electric supplied on a sunny day to charge a storage battery, how is this different to using a fan heater or tumble dryer? I assume no part of the Storage battery installation is physically connected in any way to the solar installation?

matt_drummer

Welsh_Rarebit said:

I DO have a Smart Meter and MPAN's (whatever they are) for both Electric and Gas.  If I simply use excess electric supplied on a sunny day to charge a storage battery, how is this different to using a fan heater or tumble dryer? I assume no part of the Storage battery installation is physically connected in any way to the solar installation?

The battery would be connected, it has to be.

Then you can store electricity from the solar generation.

Then the temptation would be to buy cheap electricity on a suitable tariff and then export for more money later.

You may or may not do that.

But installing battery storage makes that possible.

Therefore, to avoid any arguments, discussions or any administrative costs of any kind the panel owners just forbid any modification to the system.

Why would they spend any of their time or money on this, they get nothing out of it that they don't already have?

You agreed to the terms of the contract when you signed it or purchased the property.

That is it, you can't have battery storage under the terms of the lease. It doesn't matter how illogical you or anybody else thinks it is, it is a legally binding contract that both parties entered into.

If you want to buy the panels so you can do what you want, then do it. You have 11 years of FIT income left worth at least £10,000 I would guess?

Welsh_Rarebit

I wouldn't dream of violating my contract - I signed it and intend to stand by it.

My understanding is there are 2 payments - They get paid for the total amount of electric generated irrespective of whether it is used or not. Also they get a further payment for any surplus electric that is exported to the grid.  

I had a quote a year or so ago and was assured that the installation would be connected to the Consumer unit and NOT to the solar panel installation in any way. So I would consider this a hard-wired appliance, much as an electric cooker would be hardwired and not be 'plugged in' so to speak.

9 years ago, EV's and battery storage were pie in the sky and it's not unexpected that they form no part of the contract at that time. 

matt_drummer

Welsh_Rarebit said:

I wouldn't dream of violating my contract - I signed it and intend to stand by it.

My understanding is there are 2 payments - They get paid for the total amount of electric generated irrespective of whether it is used or not. Also they get a further payment for any surplus electric that is exported to the grid.  

I had a quote a year or so ago and was assured that the installation would be connected to the Consumer unit and NOT to the solar panel installation in any way. So I would consider this a hard-wired appliance, much as an electric cooker would be hardwired and not be 'plugged in' so to speak.

9 years ago, EV's and battery storage were pie in the sky and it's not unexpected that they form no part of the contract at that time. 

They get paid an amount for generation and another part based on the assumption that 50% of the generation is exported. Whether you use none or all of the generated electricity is irrelevant to the payment the panel owners receive.

The sort of battery storage you are considering has to be connected to store the electricity generated that you want to use later.

Your solar installation is connected to the consumer unit, the same place your battery would be connected to.

You would need to fit some sort of measuring equipment, usually CT clamps, to allow the storage battery to charge and discharge. It is all connected to the solar installation, it has to be. The CT clamps would have to measure the solar generation and it's use, and then decide what to do with any excess. That's how it works

You either need to change their inverter to a hybrid type or install a separate ac inverter.

The panel owners made provision for any future developments by forbidding any modifications to their installation. That covers everything and saves them having to think about anything that might happen during the term of the contract. It is worded carefully.

You could argue that you entered this arrangement without giving it due consideration. You would have been much better off borrowing the money yourself to install the solar panels. Even at the end the scheme, the level of FIT payments are generous enough to pay for the installation and give a profit over 20 years. Whoever signed your agreement didn't really think it through.

It may have been the case that a person just couldn't afford their own installation under any circumstances, and in those cases the rent a roof scheme will have worked well for those people. 

You are still benefitting from completely free electricity, wanting more than that with no cost is not reasonable

You are trying to apply logic and over complicate something that is very simple, you can't modify their installation in any way, they have covered every possible eventuality by forbidding any changes.

That's it, however sensible it might be to fit battery storage you can't within the terms of the contract.

The owners won't want to discuss it, there's nothing in it for them.

Its all kind of obvious, isn't it?

What you can do, is pop down Halfords (or similar) and buy a load of batteries and chargers and plug them into sockets around your home and then use the electricity stored later in some way.

What you can't do is make modifications to something that isn't yours unless you make it yours by buying it.