A solar charging system for a big garage

[char1ie]

Hmm, big post with an update seems to have disappeared. I will resubmit it in the morning...

 

[Marvo]

Hmm, big post with an update seems to have disappeared. I will resubmit it in the morning...

Your big post got caught in the moderating queue possibly because it had an outbound web link in it. I've approved it now.

 

[solarfred]

How about getting a second hand (possibly unused) GT inverter cheap and connecting to the PV. The inverter is connected to a Victron Multiplus which will allow the inverter to work via batteries as a virtual grid. Then you can connect a generator to the Multiplus which will assist with heavy loads when the batts are too low ; in winter. The PV will supply AC more efficiently when required or divert to the batts. The genny only kicks in if required. This all happens automatically. Run heaviest voltage you can to use smaller cables and get less losses. Run AC LED tubes for lighting.
The multiplus can be daisy chained if you want to add more capacity later. You can’t add old batts to new batts though.
If you find second hand (unused) PV you can do it all quite cheaply if no MCS required.
If you need help with load calculations PM me.

 

[char1ie]

I will use second hand if I find it but first I need to design the system.

At the moment I am planning two systems in the garage:

1. 12V lighting, 12V battery, 1 250W solar panel

2. 230V sockets, 2 batteries, 1 inverter, 5 250W solar panels

I don't really want to use a generator as I want to spec the system big enough for what the garage will be used for. And if I find that a tenant is running out of power I can add more panels and/or more batteries.

Charlie

 

[solarfred]

You do not need a generator but it is an effective/efficient way of covering the peak loads. Otherwise you need a lot more PV and batteries. You have not allowed for any losses in the system. You have about 20% losses in the battery system and another 20% in the inverters.
You need a proper load calculator to include the losses. You need to know how much solar power you will have in winter (PVGIS). You need to have X days latency for when there is no light which will happen in winter. Run lights in 24v minimum if you insist on doing a separate system.
How will you fully charge the batteries in winter? You may need to use a mobile charger off a genny to keep them 100% or they will deteriorate as unlikely to get a full charge if you are running loads AND trying to charge batts. off PV alone.
Once you know the total loads and the total solar power you can see how much it needs to fill the gap between the two numbers.

It also just occurred to me you are renting so will have the added problem of tenants not abiding by the "off grid code". It is hard enough to have the discipline yourself to be frugal with the power but anyone paying for the garages (or not paying for that matter) will not be so frugal. They will leave things running/lights on/fill the kettle to the brim etc..... I would consider how you incorporate controls to mitigate this?