Help on solar planning

[James]

Here is my idea,

I have a large detached garage with a pitched roof, looks like about 30degrees but haven't been out to measure.
each side has a space roughly 3m x 11m

I think I can mount 18 panels comfortably on each side.
a standard pallet seems to come with 30 panels so i intend to mount somewhere between 30 and 36 panels.
the roof faces east and west so i understand that i will take about a 20% hit in efficiency.

18 panels per side
feeding into a 6 or 8 kw inverter (one per side of the roof)

i would like to add battery storage in the region of 20 to 30kwh
later i might add some panels to the roof of the house with there own inverter.

my questions are

1. what inverter can i use that will work in parallel with others of the same make? up to a maximum of 4

2. I am hoping to keep the battery charge / discharge separate from the generation and let that deal with limiting the export to zero.

3. I have one ev at the moment but it is out all day and charges at night when i am at home average charge is 20 to 30 kwh, it is a tesla with a tesla charger, can i configure things to stop charging when it will have to draw power from the grid?

4. the generation in theory is 18kw and therefore well above the G98 limit, however i have no intention of exporting anything so do i need to use G98 or G99 forms?

5. my normal consumption at home is from a minimum of 20kwh and a maximum of 110kwh, seems to average about 35kwh. Am i working on a suitable solution?

I am based just north of coventry and have a standard 80A single phase TT overhead supply.

Any useful info or thoughts would be welcome, I am hoping to install this myself and am not by any means a keen DIYer but a proper electrical engineer that has limited experience in solar other than supplying the Ac isolator for a few industrial solar installs.

 

[plugsandsparks]

Here is my idea,

I have a large detached garage with a pitched roof, looks like about 30degrees but haven't been out to measure.
each side has a space roughly 3m x 11m

I think I can mount 18 panels comfortably on each side.
a standard pallet seems to come with 30 panels so i intend to mount somewhere between 30 and 36 panels.
the roof faces east and west so i understand that i will take about a 20% hit in efficiency.

18 panels per side
feeding into a 6 or 8 kw inverter (one per side of the roof) Sounds great, you can use the inverter design tools to help you load up the inverter strings, probably two strings of 9 panels for each inverter, pure guess (use the tools)

i would like to add battery storage in the region of 20 to 30kwh , super, Sonnen kit is well engineered, local distributor is Hero.
later i might add some panels to the roof of the house with there own inverter.

my questions are

1. what inverter can i use that will work in parallel with others of the same make? up to a maximum of 4 - Solis have all the kit you need, linked via Modbus

2. I am hoping to keep the battery charge / discharge separate from the generation and let that deal with limiting the export to zero. Good idea, you will need a CT and probably metering unit at the DNO tails and one on solar output, dont worry if they are a long way apart , i have used two metering units and modbus to extend the distance over 100M

3. I have one ev at the moment but it is out all day and charges at night when i am at home average charge is 20 to 30 kwh, it is a tesla with a tesla charger, can i configure things to stop charging when it will have to draw power from the grid? - Its possible, i have a number of Tesla chargers with contactors on the feed side, this was largely due to being able to drop them out for generator load management but the same principle can be used for your use, becareful of instability when your house is drawing just a small load .

4. the generation in theory is 18kw and therefore well above the G98 limit, however i have no intention of exporting anything so do i need to use G98 or G99 forms? Yes because in summer, you will have fully charged up batteries and not much house load so you may need a export controller to limit the output to say 3KW. Solis grid export controller works very well.

5. my normal consumption at home is from a minimum of 20kwh and a maximum of 110kwh, seems to average about 35kwh. Am i working on a suitable solution? Yes because of the battery you will still be draining at night. My general philosophy is to max out as much as you can afford.

I am based just north of coventry and have a standard 80A single phase TT overhead supply.

Any useful info or thoughts would be welcome, I am hoping to install this myself and am not by any means a keen DIYer but a proper electrical engineer that has limited experience in solar other than supplying the Ac isolator for a few industrial solar installs. Give me a DM if you want to get into product specifics and control strategy. I can also help with mounting designs as well. If you want to see one i built in Ashbourne, 56KW, ground based, TP, 60KWH batteries plus another at 18KW, roof based , TP with around 20KWH batteries on same site

Some thoughts in the txt, hope it helps
P&S

 

[snowhead]

Who is going to do the load calculations on the roof structure to see if it will take the weight?

 

[James]

Some thoughts in the txt, hope it helps
P&S

Thanks for that, it helps to have someone else look through your plans and ensure they are not stupid!!

 

[plugsandsparks]

Wish i could do it for my own home, sadly my roof is hopeless for solar. :-(
I worked out, doing it myself, it would pay back in 3 years, which is half the time most people have to wait.

 

[James]

I am thinking of starting by putting mounting rails down the length of both sides of the roof E & W facing
putting a 6kw 2 string inverter in and starting with 10 panels (5 on each side) will 5kw of panels will probably only give me about 4kw at midday because of the orientation but it will be a fairly cheep way to start for about 2k in parts and a weekend of graft.

 

[plugsandsparks]

Need to crack on to get most from this year
BTW if you are thinking about adding to the strings later, i.e. add more panels to existing string, you will get a better output if they are all the same make, model, power. I know from past, that panels are changing all the time, a year is a long time in Solar world.