Solar questions

GPK10

Hi all

I am afraid another post with questions about solar.  

I am considering solar panels and would like views on my thoughts so far.  I haven't got any quotes yet and realise that installation could be many months away as a result

Our house is in Hertfordshire, roof faces ESE / WNW.  I charge an EV, mostly in the early evenings, and we are at out mostly in the morning but home afternoon and evening.  The plan at present is to get approx 4kw of panels on each side, but not yet a battery, instead hoping to use something like Outgoing Octopus to export to the grid 

Questions are firstly - is a budget of under £10k reasonable?
Secondly I have a Podpoint 7kw charger.  Can it be limited to only taking solar and not from the grid (I have some doubts that it can)? 
Thirdly, how easy is it to retrofit a battery?  I don't really have the money and suspect that the tech and prices will change significantly in the next few years
Finally - will I get much from WNW panels in winter?  I doubt I will be able to charge the EV much in the winter except on days off from work.

I know one answer might be to switch my electricity provider to Octopus Go, certainly until I can get solar, but that is proving a problem due issues with my smart meter

Many thanks

Graham

QrizB

A year or so ago, yes you would have been able to get 8kWp of solar for £10k. Today it's less certain.

I can't comment on the Podpoint.

No, panels pointing north of West won't generate anything much in the winter.

GPK10

QrizB said:

A year or so ago, yes you would have been able to get 8kWp of solar for £10k. Today it's less certain.

I can't comment on the Podpoint.

No, panels pointing north of West won't generate anything much in the winter.

Thank you. It makes me wonder if solar will work for me, if WNW isnt realistic for several months of the year. I will think about 4kw ESE and a battery instead

QrizB

GPK10 said:

QrizB said:

A year or so ago, yes you would have been able to get 8kWp of solar for £10k. Today it's less certain.

I can't comment on the Podpoint.

No, panels pointing north of West won't generate anything much in the winter.

Thank you. It makes me wonder if solar will work for me, if WNW isnt realistic for several months of the year. I will think about 4kw ESE and a battery instead

I've just had a quick look at PVGIS (the EU-run solar power modelling tool). For my location in the central south, 50 miles or so north of the Isle of Wight, for a 4kWp array with a slope of 35 degrees:

• Azimuth -65 degrees (ESE): system generates 3600kWh/yr, peak of 490kWh in June, low of 82kWh in December.
• Azimuth +115 degrees (WNW): system generates 2800kWh/yr, peak of 440kWh in June, low of 38kWh in December.

If you use that tool you can model both your aspects, note the results then add them together to get a resonable prediction of your monthly and annual generation from your proposed array.

Reed_Richards

GPK10 said:

Secondly I have a Podpoint 7kw charger.  Can it be limited to only taking solar and not from the grid (I have some doubts that it can)?

I don't think that anything that is connected to your mains can be limited to only taking solar electricity.  Devices that divert spare solar to an immersion heater try to do this but they won't be 100% effective or 100% guaranteed not to make an error - and I think they are generally rated for devices that draw a maximum of 3 kW.  

Exiled_Tyke

Reed_Richards said:

GPK10 said:

Secondly I have a Podpoint 7kw charger.  Can it be limited to only taking solar and not from the grid (I have some doubts that it can)?

I don't think that anything that is connected to your mains can be limited to only taking solar electricity.  Devices that divert spare solar to an immersion heater try to do this but they won't be 100% effective or 100% guaranteed not to make an error - and I think they are generally rated for devices that draw a maximum of 3 kW.  

Zappi chargers do just this but (purposely) only cut in when there is excess power of about 1.4 kW.  

I'm concerned about the OP's comment of charging early evening. For the grid this is the worst time. Surely better to go onto Octopus Go and charge overnight? 

 I wouldn't bother with the WNW. But ESE with a battery could be useful. In winter when there's next to no PV generation this could be topped up using the same overnight tariff. 

GPK10

QrizB said:

GPK10 said:

QrizB said:

A year or so ago, yes you would have been able to get 8kWp of solar for £10k. Today it's less certain.

I can't comment on the Podpoint.

No, panels pointing north of West won't generate anything much in the winter.

Thank you. It makes me wonder if solar will work for me, if WNW isnt realistic for several months of the year. I will think about 4kw ESE and a battery instead

I've just had a quick look at PVGIS (the EU-run solar power modelling tool). For my location in the central south, 50 miles or so north of the Isle of Wight, for a 4kWp array with a slope of 35 degrees:

• Azimuth -65 degrees (ESE): system generates 3600kWh/yr, peak of 490kWh in June, low of 82kWh in December.
• Azimuth +115 degrees (WNW): system generates 2800kWh/yr, peak of 440kWh in June, low of 38kWh in December.

If you use that tool you can model both your aspects, note the results then add them together to get a resonable prediction of your monthly and annual generation from your proposed array.

Thank you very much indeed for taking the time to do that, the PVGIS website is very useful. I will have a look at my figures

GPK10

Reed_Richards said:

GPK10 said:

Secondly I have a Podpoint 7kw charger.  Can it be limited to only taking solar and not from the grid (I have some doubts that it can)?

I don't think that anything that is connected to your mains can be limited to only taking solar electricity.  Devices that divert spare solar to an immersion heater try to do this but they won't be 100% effective or 100% guaranteed not to make an error - and I think they are generally rated for devices that draw a maximum of 3 kW.  

Thank you. My further research says that a Zappi charger is probably best with solar, shame I didn't think about this a year ago. In theory I could charge the EV with the granny charger while the sun is out, but I won't as this takes too long and I doubt it is a safe long term option

70sbudgie

QrizB said:

GPK10 said:

QrizB said:

A year or so ago, yes you would have been able to get 8kWp of solar for £10k. Today it's less certain.

I can't comment on the Podpoint.

No, panels pointing north of West won't generate anything much in the winter.

Thank you. It makes me wonder if solar will work for me, if WNW isnt realistic for several months of the year. I will think about 4kw ESE and a battery instead

I've just had a quick look at PVGIS (the EU-run solar power modelling tool). For my location in the central south, 50 miles or so north of the Isle of Wight, for a 4kWp array with a slope of 35 degrees:

• Azimuth -65 degrees (ESE): system generates 3600kWh/yr, peak of 490kWh in June, low of 82kWh in December.
• Azimuth +115 degrees (WNW): system generates 2800kWh/yr, peak of 440kWh in June, low of 38kWh in December.

If you use that tool you can model both your aspects, note the results then add them together to get a resonable prediction of your monthly and annual generation from your proposed array.

I've just done this for my E-W set up and was pleasantly surprised to see how the PVGIS prediction is very close to my actual generation since Jan 2021.

Reed_Richards said:

GPK10 said:

Secondly I have a Podpoint 7kw charger.  Can it be limited to only taking solar and not from the grid (I have some doubts that it can)?

I don't think that anything that is connected to your mains can be limited to only taking solar electricity.  Devices that divert spare solar to an immersion heater try to do this but they won't be 100% effective or 100% guaranteed not to make an error - and I think they are generally rated for devices that draw a maximum of 3 kW.  

I looked into this to see if I could control my Chargemaster charger so that it didn't import from the grid and just used PV gen. The only solution was to replace it with a Zappi, which I don't want to do. My charging costs are too low to justify the cost of replacing working equipment (excluding the fact that it goes against my ethic of only replacing due to end of life).

GPK10

Exiled_Tyke said:

Reed_Richards said:

GPK10 said:

Secondly I have a Podpoint 7kw charger.  Can it be limited to only taking solar and not from the grid (I have some doubts that it can)?

I don't think that anything that is connected to your mains can be limited to only taking solar electricity.  Devices that divert spare solar to an immersion heater try to do this but they won't be 100% effective or 100% guaranteed not to make an error - and I think they are generally rated for devices that draw a maximum of 3 kW.  

Zappi chargers do just this but (purposely) only cut in when there is excess power of about 1.4 kW.  

I'm concerned about the OP's comment of charging early evening. For the grid this is the worst time. Surely better to go onto Octopus Go and charge overnight? 

 I wouldn't bother with the WNW. But ESE with a battery could be useful. In winter when there's next to no PV generation this could be topped up using the same overnight tariff. 

Thank you. I am certainly thinking about ESE with battery. At the moment I charge the EV early evening just because that is when I get home from work.

Octopus Go is definitely my short term answer. Unfortunately my present energy provider is halfway through an unfinished smart meter installation which I think prevents me from switching. I know that now would be a very good time to get Go while I can

GPK10

Are there any suggestions on appropriate battery size to go with a 4kw ESE system. I have seen adverts for this sort of set up with 5 or 6kw batteries, is this about right? I dont have an unlimited budget