Starting system No.2

[DMNknight]

So since my last post here, I was happily getting along with some one who contacted me here for a full solar install. Everything was going swimmingly except there was a delay on batteries.

So I waited, preferring to have a once off install with new batts, rather than possibilities of complications with second hand batts.

However this person has decided to just ghost me. No replied f'all.

 

So, this is start no.2.

I am going to be testing a DIY battery system which will work at 48v... this seems to be a magic number in Solar. I've found a source of discarded Li-Ion batteries, so I could possibly start with a 48v/2.2A 4-8 hour system and work up from there. Once I am confident the setup works, I'll be doing a whilesale import of these batteries to give myself a 16-24 hour powerwall

 

However I need a list of the rest of the components I need to purchase.

For august, I specifically ran the house hot, so that I could get an upper limit of what I need to cater for. This turns out to be an average of 16kWh/day.

I have a 2.7Kw generator (Manual start) for those days when the batteries are going dead, eskom is dead and the sun is hiding behind clouds, so it will be rarely used.

 

I am assuming I need a Hybrid inverter to cater for the Solar Panel input, Eskom input, battery charging and input and Generator input.

I will need a charge controller for the batteries right? Are there modules I need to link solar panels together?

How many panels of what rating will I need? I prefer larger because the solar geyser has taken the prime roof location, so I need to place the panels well. A smaller number of them will be advantageous.

I have someone who can do the roof mounting for me and similarly an electrician who can tie all of this into the house main circuit board with compliance.

 

I just need help with all the other minutae because my trust in professionals is diminished >:(

[Chris Hobson]

10 hours ago, DMNknight said:

 

I just need help with all the other minutae because my trust in professionals is diminished >:(

So you basically looking for unprofessional help . Might I suggest you look at the Renesola inverter Bonanza have on special at the moment. It cannot be bettered. It is 3kW full hybrid (rebranded Infini).  If you are worried about the lack of a warranty buy two and you still come in at a very good price. Your advantage will be that you can go solar whilst you finalise your batteries. The permissible 4500W of panels should generate your 16 kWh. Panels are not really an issue as the built in SCC has a wide operational voltage. There may be some sizes that are less suitable but really are a minor consideration.

There - some unprofessional help for free.

 

[___]

1 hour ago, Chris Hobson said:

permissible 4500W of panels

I think regulations might only allow around 3kwp for grid-tie on a single-phase connection, just something to check.

I wish I only had 16kwh in a "hot" house. More like 40 if we keep it really hot, maybe below 30 in winter if we're careful. In summer it comes down to around 16 some days :-)

But in Cape Town it remains best to buy all the cheap electricity at the bottom and only generate the bit above 600kwh, so up to 20kwh a day is sufficiently low to not bother with solar :-)

[___]

12 hours ago, DMNknight said:

I will need a charge controller for the batteries right? Are there modules I need to link solar panels together?

Depends. Some inverters are multi-function devices that have one included. The infini Chris mentioned is one of them. The blue stuff I like to sell to people don't have it in the box, it's external.

You also need to be aware of the inverter topology. Some inverters have a boost stage and others don't. Those with a boost stage generally take their PV  input below 150V, and use that to charge a battery bank at 48V, and then boost from there to the required 350V (ish) that is required to make 230VAC (RMS). Other inverters take their PV at a voltage above 350VDC so that they need no boost stage to make AC. This will have an impact on your choice of inverter, especially if you have roof space issues. You may not be able to string enough panels together to go up that high. This might push you towards multiple smaller strings with more than one MPPT.

The inverter Chris linked is a high-voltage-input model.

There are things called combiner boxes which are for linking parallel strings together and some other safety functions.

12 hours ago, DMNknight said:

How many panels of what rating will I need? I prefer larger because the solar geyser has taken the prime roof location, so I need to place the panels well. A smaller number of them will be advantageous.

Power rating is proportional to the area. You need about a square meter to make 150 watts. You can buy smaller panels and install more of them, or larger panels of which you will need less, but the overall area problem will remain the same. Larger panels usually work out cheaper in terms of rands per watt. A 300W panel is about 2m x 900mm in size (around as big as a standard door).