Wanting to learn

Hi All

I am a youth worker based in Cornwall, UK and over the last few years I have been teaching myself several new hobbies as I head towards 60 and possible retirement! Although not probable!

A few years ago we were able to buy our first house which was amazing and I turned to learning woodwork, permaculture/food forest gardening, electric bikes and off-grid living. We had already lived two years in a 35ft library van using off-grid water and a compost toilet but we had an electric hook-up. So, on arriving in our house I built a shed at the bottom of our garden and have been using a small off-grid system to charge hand-held batteries and my bicycle battery. The system consists of:
4 x TPS-102 12v panels with rated power 12w @ 17.5v 4.8ah capacity
2 x Alphaline xv24 MF batteries running 2 x 12v
1 x Steca solsum 10.10f 10a 12/24v solar charge controller
1 x Sterling Power 12v Pure sine wave Pro Power SB 300 watt inverter

The system works and in the summer works well. Charging a battery usually takes the system from green to orange. I also have a Honda EU10i generator in case I need to top the batteries up. But as you can tell this system doesn't perform so well in the winter. It also restricts me as I have a 1400w mitre saw which I take back the house to run. I am thinking of buying a bench drill press which will run 350w. I need to upgrade my system. As I am still learning I am hoping for some hand holding!

Can I run this system in tandem with another system please?
Can I upgrade this system by adding panels, a more powerful inverter, etc please?
Or am I better off scrapping and starting again?

I don't have a lot of money and so I am hoping that I can upgrade elements to be able to keep this system running until a new system in place. A for instance, as I want to run the 1400watt mitre saw, is it a good idea to purchase an inverter for the system first? But if I do, should I upgrade the batteries as well?

Many thanks for all the replies.

Rich

Welcome Rich,
Pics and a system schematic helps.

Thanks - hopefully this will help.

Beautiful garden, miss living in England. First thing I would do is clean it up some, wires all over the place but that's just me. I'm learning solar myself but have been in the electronics field for over 30 years.

My preference would be to just upgrade the system. And the first thing I would upgrade is the SCC (solar charge controller). Yours is only 10 amps and in my opinion, adding more panels first could overdrive what you have now.

Dan

Thanks Dan. I love being in our garden, it feels like paradise! I am trying to fit a jungle gym in somewhere. You are welcome here on holiday anytime. We have a spare bedroom and are happy to accommodate families in whatever way we can fit them in!

Yes the wiring! I was so happy to get it working I didn't want to stop it working so left the wiring as is.

So, how do I know what to upgrade the SCC to please? If mine is 10amps how do I work out what is high enough to cope with say 2000 watts please?

Thanks

Rich

From my understanding the order goes like this.

1. Determine total daily load and # of days backup wanted.

2. Size battery (battery pack) to fit step 1.

3. Size PV array to charge batter pack in one day.

4. Work out current to determine SCC charge.

Will has some great videos on sizing your system.

Here is a picture of my test system.

Thanks. Who is Will and does he post on Youtube please? Your test system looks very clean. So, I will look at improving my wiring.

1. I run the chop saw almost daily and that draws 1400 watts. What do you mean by days backup please?

I'll answer the next questions once I understand the days backup.

Thanks for all the help.

Lol,. Will owns this site and yes he has a YouTube site.

Look up Will Prowse

During the day when the sun's out and your using power, if your system is sized right your battery should stay full to almost full during the hours of sun. Now if the next few days have rain or heavy cloud cover you will kill your battery real quick if you didn't size it for a few days backup.

Link to video

Just discovered who Will is and I am just watching some of his videos now. And now reading your posts so will check that link. Thanks.

That video is very useful. I checked out his book and will probably buy.

Having used his calculation I am looking at a 12000wh system which seems excessively large but it will be running a couple of power tools. So going with the rest of his advice on his video I need to look at how I run my batteries.

Currently I run them as a 12v system but if I get two more Alphaline batteries and run them in series to make 48v battery system. The Alphaline are lead acid with 86ah for each which is 1032wh but Will reckons on 50% of that which means with 4 batteries I have 2064wh system.

So, if I need 12000wh (2000w x 2 hours a day x 3 days of backup). The batteries above will work. But I will have to upgrade my Solar charge controller and my solar panels. In order to run the above system I will need a 12000wh / 5 hours of good sunshine a day which is a 2400w solar array. If I now divide the 2400w array by 48v I need a 50a/h controller.

So the order it looks like I need to go in is to buy a 50ah 48v solar charge controller.

Followed by 2 x Alphaline batteries.

But then I will need a different inverter and also at some point to upgrade the panels.

And a what if I want to add on to this system to run some of my house goods such as a freezer or fridge. May as well use all this power! Can I then buy lithium batteries because Will says they are better.

This is harder than I thought! Thanks for pointing me in the right direction though.

If you have any more advice or can see errors in my thinking please just shout.

Now another thing to consider is how much power do you use during the sun hours and dark hours. During good sun light your panels might make enough power to run your stuff and not draw from the batteries. This could lower your battery size.

This is harder than I thought. It seems like this an endless calculation!

I would meter your usage on a high use day to see what you get.

Hi

I have been reading and trying to see a way through and with a limited budget, asking the question, "Where do I start?" So I have a plan!
1. Purchase a 100 watt glass solar panel - but how can I tell what is a good panel and what is cheap. I have listed two from Ebay:

(Sell old ones)

2. Add 2 x Alphaline batteries

3. Increase solar array to 4 panels in total.

4. Purchase one 40 amp MPPT Controller

5. Purchase second 40 amp MPPT Controller

6. A 3000w power inverter

It might be a long road to get there but in this way I can keep the current system running until I get to step 4 or 5. At this stage I might need to bite the bullet and do 4 and 5 together.

Thanks for all the help.

Rich