Please help a newbie with Inverter advice

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JohnStein

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Hi,

I have a small business running from home. Eskom will quickly ruin what has taken me 14 years to build up!

We have 7 x pc's, 1 x small Server, 2 x laptops, 12 x 16" screens, inkjet printer, router and modem. I believe that I should use a pure sinewave inverter but I have no idea what size, number of batteries etc. I would also like the unit to be connected to my board so that the changeover is seamless. Obviously I'd also like the unit to last approx 4 hours.

Please could somebody advise which is the best way to go, with any recommendations.

Thanks in anticipation!
 
I'm guessing 3500w, or a little less, so you will need a lot of batteries.

You may need to check your equipment to get a more accurate figure.

Or you just need something to tide you over until the generator kicks in.
 
Last edited:
I would say that you would need between a 2.5KVA to a 3.0 KVA generator to run what you want above (and a little bit more). If you want an inverter or generator connected up to the board it would probably be best to get a contractor to do it and most companies supplying you the generator or inverter should be able to give you a name of a sparkie who can set it up for you.
 
How much money do you want to spend?

Batteries and inverter will be quite costly up front but cheaper in the long term. A nice diesel generator will be cheaper up front but cost more to keep running.
 
What do desktop PC power supplies run at these days - somewhere between 300-400W?

Does the server have a standard PSU?

PC's + server 8 * 400W = 3200W alone
Screens (if not CRT's) somewhere around 20-30w = 12 * 30W = 360W
Laptops and routers - probably around another 200W max.
Inkjet printer - AFAIK usually not recommended to use on a inverter/generator.

My guesstimate is you might get away with a 3KVA generator/inverter but would be safer with 3.5KVA-4.0KVA system, especially if you want a few low energy lights.

So you'd need the inverter plus probably minimum 4 x 100ah deep cycle batteries as well as inverter charger and an electrician to wire it all in. Rough guess R15-20K price range with labour although maybe you can get a cheaper deal.

There are a lot of excellent installers, so probably worth getting a few quotes from somebody who does this professionally.
 
Thanks for the replies.

I realise that a generator would be more cost-effective initially. But I'd really like to go the greener route if possible.

I've had 2 quotes:
4000 Watt 48v with 8 batteries fully installed R38,000 incl
3000VA with 6 batteries (approx 4 hrs backup) R30,000 incl

What's the difference between Watts and VA?
 
Jola said:
I'm guessing 3500w, or a little less, so you will need a lot of batteries.

You may need to check your equipment to get a more accurate figure.

Or you just need something to tide you over until the generator kicks in.
Click to expand...

I would also say an inverter with a large battery that gives a generator a minute or two to settle in.
 
JohnStein said:
Thanks for the replies.

I realise that a generator would be more cost-effective initially. But I'd really like to go the greener route if possible.

I've had 2 quotes:
4000 Watt 48v with 8 batteries fully installed R38,000 incl
3000VA with 6 batteries (approx 4 hrs backup) R30,000 incl

What's the difference between Watts and VA?
Click to expand...

V * A = Watt
 
JohnStein said:
Thanks for the replies.

I realise that a generator would be more cost-effective initially. But I'd really like to go the greener route if possible.

I've had 2 quotes:
4000 Watt 48v with 8 batteries fully installed R38,000 incl
3000VA with 6 batteries (approx 4 hrs backup) R30,000 incl

What's the difference between Watts and VA?
Click to expand...

I don't really see how this is greener. Sure maybe where you live but from manufacturing to disposal I'm pretty sure a generator is about the same if not better in the long run.
 
People are installing inverters all over the show suddenly. Which is hardly surprising as they are relatively cheap to install, quiet and automatic. We put our entire home plug circuit plus a few lights (obviously minus the heavy load appliances, oven, geysers and pool pump) onto a 2kw system that so far has worked flawlessly during several load sheddings at a cost of R9500 all installed. You don't even realise that the mains is off until you try to use the oven.

But you have to wonder. It basically defeats the point of loadshedding. The electricity doesn't come from nowhere and to make matters worse inverters apparently lose something like 20-30% of the energy due to inherent inefficiencies. So, simplistically, if the inverter supplied 10kwh during loadshedding, ~13kwh will be used subsequently to replenish the batteries, not to mention the ongoing additional power that will be used to keep the batteries topped up. So if every household ultimately installs inverters, there will be no net reduction in consumption during rotating load shedding, in fact it would theoretically be higher due to all those systems recharging and making up for the lost 20-30%.

So, a great solution for an individual home or small office, but not much benefit at all if everyone did it?

Although, it must achieve spreading the load over time as the batteries charge over a much longer period than the original load shed time, and also the heavy load items like geysers, heaters, air conditioners, pool pumps and ovens would not be on inverter. I am curious, though, as to whether there is a point at which if enough people install these systems, switching an area on after load shedding could become problematic due to the sudden combined additional load of thousands of inverters recharging.
 
garp said:
People are installing inverters all over the show suddenly. Which is hardly surprising as they are relatively cheap to install, quiet and automatic. We put our entire home plug circuit plus a few lights (obviously minus the heavy load appliances, oven, geysers and pool pump) onto a 2kw system that so far has worked flawlessly during several load sheddings at a cost of R9500 all installed. You don't even realise that the mains is off until you try to use the oven.

But you have to wonder. It basically defeats the point of loadshedding. The electricity doesn't come from nowhere and to make matters worse inverters apparently lose something like 20-30% of the energy due to inherent inefficiencies. So, simplistically, if the inverter supplied 10kwh during loadshedding, ~13kwh will be used subsequently to replenish the batteries, not to mention the ongoing additional power that will be used to keep the batteries topped up. So if every household ultimately installs inverters, there will be no net reduction in consumption during rotating load shedding, in fact it would theoretically be higher due to all those systems recharging and making up for the lost 20-30%.

So, a great solution for an individual home or small office, but not much benefit at all if everyone did it?

Although, it must achieve spreading the load over time as the batteries charge over a much longer period than the original load shed time, and also the heavy load items like geysers, heaters, air conditioners, pool pumps and ovens would not be on inverter. I am curious, though, as to whether there is a point at which if enough people install these systems, switching an area on after load shedding could become problematic due to the sudden combined additional load of thousands of inverters recharging.
Click to expand...

This is why I want to go off-grid with my installation. My requirements are exactly the same as yours. But I'm willing to spend double that amount (As a start) to charge the batteries via solar, with a external source as a secondary option.
Who did you do yours through?
 
@OP: You should consider running a minimum of equipment. I'm sure you can get by.

Maybe: 2 x pc's, 1 x small Server, 2 x laptops off their batteries, 2 x 16" screens, router and modem
 
buy one of those ellies power meters for R300 and measure your power requirements. Install a UPS inverter onto those plugs only and then run it on that system, auto changeover is your friend. for 4 hours count on 400Ah per 1000w average use min.
 
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