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Beginner solar system design for a house


McWidowmaker
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I am looking into doing a solar system for my house. Current usage after doing solar geysers, gas stove and all LED lighting is 17kwh per day. About 6kwh of that is during 10am - 3pm. The peak consumption is around 4kw, only exceeding that when I run my tumble drier, which is some evil thing from hell that consumes about 4.5kw all by itself.

 

The system I am looking at is 16 x 250 panels, a 5kw microcare inverter(48v), with a 100a microcare MPPT charge controller. I'm looking to put on 4 x 200ah lead carbon batteries and later expand this to 8. Anything I should look out for, or anything you would change? Pitfalls? Ideas?

 

 

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Hi Mc this looks like a very nice system and when you get all 8 batteries you can get off the grid.

The Microcare inverters allow for back-up power from a generator or municipal supply.

 

I recently repaired my mom's tumble-drier and found it has two heat settings so I would only use it on low also because it burnt some of the wires

 

Where are you getting the Lead Carbon batteries from ?

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You will work 4 batteries quite hard. Theoretically 200Ah x 48V x 50%DOD = 4.8kWh, so your 6kWh overnight will pull the batteries very low. I was doing the same on my system, so would have to start the generator in the morning to power everything, but now have 8 batteries (150Ah) and don't have that problem anymore.

 

Are you going to have a backup generator, or still have Eskom? 

 

17kWh is still a lot. When you go fully solar you will find a lot more stuff to turn off, I know I did!  :P

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Why not use a clothes wire to dry your clothes? Or something a bit more efficient?

If MWM is in the Western Cape then he NEEDS a tumbledryer. We live in the Karoo and our clothes dry on the line but I have spend one awful month during winter in the Cape with it cold and wet. I was grumpy and irritable by the time we left. I know know why the Cape Flats have a drug problem. I would also do tik if I lived there  :P

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  • 3 weeks later...

Hmm, sorry, was away for a while. From my calculations 4 batteries will not really be enough, I suspect I will need 8. I am changing the remainder of my lights to LED tomorrow, which should reduce my consumption a bit more. I have a few pc's that is running 24 hours, which is messing with my consumption, which I cannot really get rid off. The rest I think I have pretty much taken care off. I am going to keep my eskom supply, but it should be reduced to almost zero. My wife uses the tumble drier for towels to get them soft and fluffy. Think I am going to ask her to hang dry them and tumble dry them for 15 minutes  :lol:

 

I am still looking for a supplier on the batteries. I am busy checking prices today. Looks like I will be able to get them for close to R6k per battery. 

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What fridge and deep freeze do you have I have a Bosch fridge (58 W) and AEG deep freeze (66W) + 10 LED lights. One can reduce ones needs to negligible (compared to what I had previously - Minus 40 fridge and deep freeze which were designed to run off a generator on a couple of hours each day (770 W each)).

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Would all those 16 PV panels be mounted on the same roof with the same angle?

If yes, then 100Amp should be ok.

Personally I would rather go for 2 x 60Amp MPPT controllers. You have some headroom then to expand if needed.

 

Your battery bank is way too small for what you looking to do.

I had a similar configuration with a 225AH battery bank. Some days it cycled 3 times!!!

If I had the money I would rather go for 600AH bank.

 

Regarding computers running 24/7 - I also had this in my house.

Eventually found the "media server" using 300w while it just sits and idle.

Got a new PC with better specs. Now just using 50w on idle :)

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Hmm, yes, they will be on the same angle, but not all on the same roof. I don't think I have the roof space on the one roof to mount all the panels next one one another. There is also a chimney which shadow I would like to avoid if possible.

 

The battery bank I will be going for will either be the Navara 200ah 12v x 8 which should give me 200 usable ah or the Deltec Lead crystal bc-6cnfj-200. The lead crystal batteries is damn expensive, so I'm still trying to figure out if they will be worth the extra cost. I will try it with the 400ah battery bank and if I run short, I will add 4 more batteries. Hope that won't be needed, the battery cost is really ouch.

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  • 1 month later...

We always tend to solve the problem, i.e. 17kwh per day, instead of solving the cause of 17kwh.

 

Want versus needs:

- Family training and indoctrination regiment to switch off that what is not needed, must lower consumption at all times.

- Stove on gas, oven on Eskom - unless there is spare during the day, then use the oven.

- Geyser on EV tubes or flat panel - and train the family the cost of warm water.

- Shower heads the water saving ones, baths only as a treat once in a while.

- Lights on LED, the halogen outside lights also.

- Fridge Freezer A++ or if you can, A+++

- Computers that has to be on, reduce their power consumption.

- Use the power daytime, store only what you NEED for nights.

- And do not forget the family training and indoctrination regiment to switch off that what is not needed, must lower consumption at all times.

 

Try and get down to 50% of your current usage, 8kwh or less, then go solar. To get there, will be a huge lifestyle changer. Trust me.

 

And sell the working stuff on Gumtree to help others, it is greener than throwing it away.  :D

 

Alternative is you get the 17kwh sorted, batteries not lasting as expected, cost a really expensive, and then in winter you discover you need more panels = rather huge disappointment as some of my friends and businesses found out.

 

Solar is a lifestyle changer, a love affair for Electricity, she is a very dangerous and expensive mistress ...  :wub:

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