diy solar

diy solar

South West of France thinking about taking the plunge

tbld

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Hello everyone,

I live in the south west of France and after receiving our regularisation of our power bill at the end of the year, I am thinking of taking the plunge into solar. I am a reasonably capable DIY person but would love to have some people to bounce my ideas off.

So we have an average daily usage of 40KW. We are currently on a 9KVA Supply single phase. We have an older home (over 100 years) that has heatpumps for heating and AC ( Though we rarely need AC ) and also for our water heater. We have a pool that has a 750W pump that needs to run 8 hours a day minimum over the summer. We also have an electric car that is out most of the day and is currently charged over night about 20KW per day.

Due to the shape and orientation of our home and garage solar on the roof, which is more popular and allows for feed in tarrifs, won't be possible. So we are thinking a ground mount system

My thinking is that I can shift a lot of the load to day time by running the heaters to keep the house warm all day instead of just firing them up a few hours in the morning and the evening and I can shift the hotwater to heat day time only. But to get full benefit with the car I am going to need some batteries so a hybrid system is probably going to be the way to go here. I could also filter the pool all winter to use some excess energy I suppose though kind of pointless if too cold to swim.

I went and got some local quotes that were 10 - 12 year ROI and not very encouraging. I have since got parts only quotes that would bring the ROI down to the 4 year mark assuming I could become energy independent or close to it. Which is fine as we intend to stay in the home till our youngest leaves in around 10 years.

The system I am looking at is 15KW of Solar, dual deye 8K inverters in parallel and 20KW of battery. I feel like I am going to need more battery then that thought and maybe fewer panels. My thinking is that in summer I will produce enough to charge the battery in a few hours and then I will just be using for the sake of using. I can get the car on to charge most nights before the sun goes down as well. But in winter I can't help but feel it won't be enough. Would I be smart to double the battery? Knowing in summer it won't really be used but in winter it may be essential?


Sorry bit of a brain dump but maybe I am not asking the right questions be happy to hear any advice!


Thanks
 
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This maybe of interest to you, developed in the UK and taken over to France. The code has modified to fit in with French consumption meters to make billing work, it diverts any excess over internal usage to a load such as an immersion heater of up to 6kw. I built the UK version and have hot water from my panels 6 months of the year. Being further south you would achieve more months than I could.


On the ROI they are similar in the UK, I went second hand and DIY for 2 to 3 year payback.
 
15kWp panels sounds quite right, but keep in mind that panels are the cheapest part of almost any solar system nowadays. 20kWh battery is a good start, but I suspect that you will end up with 40-60kWh with EV.
 
Hello everyone,

I live in the south west of France and after receiving our regularisation of our power bill at the end of the year, I am thinking of taking the plunge into solar. I am a reasonably capable DIY person but would love to have some people to bounce my ideas off.

So we have an average daily usage of 40KW. We are currently on a 9KVA Supply single phase. We have an older home (over 100 years) that has heatpumps for heating and AC ( Though we rarely need AC ) and also for our water heater. We have a pool that has a 750W pump that needs to run 8 hours a day minimum over the summer. We also have an electric car that is out most of the day and is currently charged over night about 20KW per day.

Due to the shape and orientation of our home and garage solar on the roof, which is more popular and allows for feed in tarrifs, won't be possible. So we are thinking a ground mount system

My thinking is that I can shift a lot of the load to day time by running the heaters to keep the house warm all day instead of just firing them up a few hours in the morning and the evening and I can shift the hotwater to heat day time only. But to get full benefit with the car I am going to need some batteries so a hybrid system is probably going to be the way to go here. I could also filter the pool all winter to use some excess energy I suppose though kind of pointless if too cold to swim.

I went and got some local quotes that were 10 - 12 year ROI and not very encouraging. I have since got parts only quotes that would bring the ROI down to the 4 year mark assuming I could become energy independent or close to it. Which is fine as we intend to stay in the home till our youngest leaves in around 10 years.

The system I am looking at is 15KW of Solar, dual deye 8K inverters in parallel and 20KW of battery. I feel like I am going to need more battery then that thought and maybe fewer panels. My thinking is that in summer I will produce enough to charge the battery in a few hours and then I will just be using for the sake of using. I can get the car on to charge most nights before the sun goes down as well. But in winter I can't help but feel it won't be enough. Would I be smart to double the battery? Knowing in summer it won't really be used but in winter it may be essential?


Sorry bit of a brain dump but maybe I am not asking the right questions be happy to hear any advice!


Thanks
i would also consider DIY if you are able to. as regards pre used panels, new panels are now so cheap that i wouldnt bother with pre loved. i would def look at non 'named' batteries, thats where there could be a massive saving, especially if you can build the battery yourself, even assembling it from a kit (look at Fogstar UK for examples and prices)
 
Salut et bienvenue... sounds like a great project - are you anywhere near the huge solar farm at Cestas?

I see the Winter as being the issue - in the summer you can presumably heat the pool with excess energy too, or run some AC.

If you need, ideally, to put 20kWh of energy into the car and run the house, including heatpump from dusk to dawn, then IMHO you will need more than 20kWh of battery storage.

Also, 15kWp of panels will likely only yield around 930kWh per month in Dec and Jan and not much more in November - I clicked roughly where Cestas is on the map - see...

So, that is average of only 30kWh per day, with ideally positioned panels, which will result in a shortfall on your 40kWh daily usage. You won't be needing to filter your pool all winter to use it up !

My "finger-in-the-air" suggestion would be 20kWp of panels and 40kWh of battery. But, as others have said, battery is easier to add on later when you have a better feel for your usage patterns.
 
Firstly wow, thanks for all the messages. I am hearing you loud and clear install as much solar as possible I can add more battery later. My current plan involves a custom order from china for the kit. They are recommending 30 560W panels If I up that to 32 I will have nearly 18k of solar panels. Which split between the 2 inverters and allowing for a bit of loss should keep me right at the 8K peak that each of those inverters allow. Also I can do 4 strings of 8 like that so its simple. Any more I need to look at another inverter I guess.

Doing some research those inverters have a smart load function which if I understand correctly will do the same as that diversion kit. The one thing I am not clear on is the schematic for the inverter has the house off the AC input and uses the feedin to power the house and the meter. But will limit the feedin if asked so only the house is powered. But it also has a load circuit. I was thinking to move the whole house to the load circuit. as 16KW of output is way more than my 9KVA feed at the moment. What am I not understanding here?

Next stop is a trip to the Maire to see if they are cool with all this, as it will take up about 77m2 but shouldn't be too tall so fingers crossed. Also its facing another field so I don't see the neighbors complaining.

Just downloaded pvSOL so may have some pictures to share soon.
 
Salut et bienvenue... sounds like a great project - are you anywhere near the huge solar farm at Cestas?

I see the Winter as being the issue - in the summer you can presumably heat the pool with excess energy too, or run some AC.

If you need, ideally, to put 20kWh of energy into the car and run the house, including heatpump from dusk to dawn, then IMHO you will need more than 20kWh of battery storage.

Also, 15kWp of panels will likely only yield around 930kWh per month in Dec and Jan and not much more in November - I clicked roughly where Cestas is on the map - see...

So, that is average of only 30kWh per day, with ideally positioned panels, which will result in a shortfall on your 40kWh daily usage. You won't be needing to filter your pool all winter to use it up !

My "finger-in-the-air" suggestion would be 20kWp of panels and 40kWh of battery. But, as others have said, battery is easier to add on later when you have a better feel for your usage patterns.
I am about 150Km further south of Cestas. I inputed into that tool and with 17.92 (32 560W panels) and 14% loss. Over winter I am at about 1236KW so I am right on the limit of 40KW per day.

While it would be fantastic to be grid independent I am not too concerned if I need a little import over the winter.

Thanks for the advice and the tool.
 
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