diy solar

diy solar

Scottish Off Grid Solar System

tonyg

New Member
Joined
Apr 5, 2022
Messages
136
Hello good people!

I would like to start my first post by thanking Will for creating this platform, for his book and every video he posts on his YouTube channel!

For a few weeks now I've been trying to design a 48v off-grid solar system, and I've been looking at Will's videos, read his book, read as much info as I could online - I work full time, and have small children as well, so whatever time allows in the late nights or early mornings I spend on this project. I'm a bit stuck on how to go forward, and your advice and thoughts are well received.

Scotland is a beautiful country, but pretty overcast from a solar production point of view. When the sun shines it is wonderful, but when it doesn't, it is quite gray. My needs hover about 7kwh a day, but that is without taking care of light switches and other equipment. This production would definitely be achievable in the summer, but not that much in the winter (pvfitcalculator says an average of 9.14kwh/day of production). Of course, with practice and care, we can lower the house usage considerably, especially during the winter time.

I have room for about 10-12 large-ish solar panels to face South, and given the overcast weather I've been looking at the bifacial panels, specifically, JA Solar Half-Cell Bifacial 410w panel - monocrystaline. I plan to paint the roof of the garage where some of these will go with aluminium solar paint that reflects light well, and hence increase the production on dull days. If you think of a better panel system for this situation, please let me know.

For batteries, I'm looking to do about 2x4.2kwh system with LifePo4 batteries (pre-built), or even larger if I build it myself from cells.

The bigger question is for the inverter + charger, what should I do? Should I go forward with an all in one system from one of the Chinese suppliers such as Growatt, EASUN, Voltacron, etc? This would be best from a financial point of view and best from practical point of view, but I would like this to be reliably working 24/7 off grid. Hence, a good MPPT to squeeze most of the energy from the panels, as well as ok-ish energy consumption are essential. What brands do you recommend from this category? Is there a better all-in-one system out there?

Or should I go down the more expensive route to get Victron components separately and make up a charger/inverter system from these? That will increase the cost considerably, but I'd rather do it well once, than fiddle with it after a couple of years of usage.

What is your experience, what do you suggest and how would you go forward?

Thank you all very much for reading this post and for offering your advice.
 
According to the electricity consumption of 7kwh, a week needs 49kwh of electricity, the power frequency inverter efficiency is 85%, so according to the complete lack of solar charging to support a week of electricity, the battery is 50kwh, and the solar panel efficiency is 1kw ⨉ 0.7 is equal to the actual power generation of one hour, mainly depending on the region.
 
There is no need to use double panels

Space constraints would be one. You probably wouldn't gain much, but some... in the same vein, if one gets decent wind, especially when the sun is down, some energy can be had from wind. Not much, and one would need good quality equipment (expensive) but some.

That will increase the cost considerably, but I'd rather do it well once, than fiddle with it after a couple of years of usage.

I don't think fiddling with it after a couple of years of usage is a bad idea, actually :·)
I've had a CCC (Cheap Chinese Clone) All-in-One for over a year now. I do have a spare one in case it blows, but so far it hasn't :·)
The main advantage of those (a good one in your case) is that you can charge the batteries off a generator if needed.
And if you get parallel-capable ones, you can have two smaller ones, paralleled, unlikely they would blow at the same time, gives you some time to replace it.

Now, the batteries... they're the really expensive part, and the one most likely to give you headaches*. I would invest in good ones from the start.

[EDIT] * Actually, for headaches and expense, wind can be worse ;·) That would definitely be something to play with after some time.
---------- And of course, if you have access to running water, like a creek, and can get some slope below it... you would have the Holy Grail of renewables - ---------- hydro :·)
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