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Inverter suggestions for the elderly


gallderhen

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Hi,

 

I've been approached by my retired-parents with regards to becoming Eskom independent or semi-independent. My knowledge of going solar is very limited to what I've researched and read up on on this forum :)

 

They want to go Solar during the day, with Eskom at night (for now) with the option of going completely offgrid later (if/when battery prices drop to affordability). I guess the preferred usage would be solar during the day, Eskom at night and later on in life solar during the day, batteries until optimal DoD and then Eskom if the sun's not up by then.

 

Being pensioners, their needs are very basic i.t.o electrical usage (geyser, vacuuming, stove/oven for baking and cooking, aircon, TV, lights etc) and most of the usage will be during the day (with probably TV and lights only, at night). I'd estimate they use about 6-9 KWh per day on average, peaking at about 3KW when using the vacuum or oven.

 

So my first thought was that a hybrid inverter and some panels would suit them best. Now, they aren't very technically inclined, so something that's a single unit and  basically plug-and-play would be better (they are too scared to fiddle with settings of things they don't understand). Also their budget is in the range of R15-30K for the inverter alone, possibly stretching it to 40.

 

In conclusion I'd like your opinion on suggested inverters for them please.

 

-G-

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33 minutes ago, JDP said:

What are their kWh/d requirements. You have to start there. What do they want to power. 

They do about 6-9KWh on average a day, and I assume that it peaks around 3KW when the vacuum goes on? Ideally they would like everything to run on solar during the day.

I'll only be able to tell real numbers if I stick a monitor on their mains.

 

-G-

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5kva Axpert, 2kW array, battery bank, mounting hardware and safety equipment. All this will cost you about R50 000 to R60 0000 depending on where you buy.

Install a solar geyser, split the DB, leave kitchen on Eskom and run the rest of the house off solar. Did the same for my parents, cut their electricity bill by approximately 70%. 

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2 minutes ago, gallderhen said:

They do about 6-9KWh on average a day, and I assume that it peaks around 3KW when the vacuum goes on? Ideally they would like everything to run on solar during the day.

I'll only be able to tell real numbers if I stick a monitor on their mains.

 

-G-

 

You can't go wrong with the Goodwe 5048ES. Proper hybrid inverter. You can contact Mike on the forum, he can get you one.

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7 minutes ago, JDP said:

Are they able to push back into the grid ? If not then using a true hybrid wont help a lot. Then you can stick with a option like the Axpert that uses batteries.

A hybrid is more efficient than an off-grid inverter. They can also blend grid and solar power.

Hybrid is the way to go in my opinion.

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I would suggest to go for a 5kVa Axpert. It is an all in one unit, runs of batteries and off solar and will cater for their needs. What will eat into their budget is the batteries, Wire the stove, oven and geyser separately to run off grid only, not through the inverter. 

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11 hours ago, HeinTheTerrible said:

The Renesola unit (rebranded Goodwe) can be had for R39k

And then you dont get any firmware updates. The Goodwe had charging issues with firmware and only the updates fixed it. I wont take a chance with it. But that is just me.

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Look at JDP's earlier post. First you have to determine whether you are allowed feeding to the grid and then the conditions that apply. Our municipality allows it but credits you R0.685 per Kwh and charges R1.35. No credit balances or rollover to next month is allowed. That makes grid tied a really stupid idea. I have a 2.3Kw panel array, 2 x 4Kwh Axperts in parallel and 450 Ah battery bank. Water is heated by 16 evacuated tube heater. The stove is gas and we use a wood burning heater in winter. Inverters are controlled by AICC program and come on at 1:30 am to 17:30 pm and then switch to grid. Batteries are down to about 80% SOC before the panels generate enough to drive the house and charge the batteries in the morning. So far electricity bill is down by 65%. You have to watch power consumption and not drawn high currents from batteries. I try to stay below 40A. It won't be quite so rosy in winter. On average the house load is around 800W when appliances that draw a lot of power are off. Also it is only my wife and I in the house most of the time.

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13 hours ago, JDP said:

And then you dont get any firmware updates. The Goodwe had charging issues with firmware and only the updates fixed it. I wont take a chance with it. But that is just me.

I'm still waiting on confirmation about this. I'll keep you guys up to date on this matter.

 

3 hours ago, ebrsa said:

Look at JDP's earlier post. First you have to determine whether you are allowed feeding to the grid and then the conditions that apply. Our municipality allows it but credits you R0.685 per Kwh and charges R1.35. No credit balances or rollover to next month is allowed. That makes grid tied a really stupid idea.

2

Regardless if you're allowed to feedback or not, using a hybrid inverter just makes more sense. You skip the round trip efficiency loss (+/-65%) of off-grid inverters and send power produced by the panels straight to the load (+/- 96%) before/after the batteries are charged. The Goodwe unit's comes with an energy meter so you can set it to not export power.

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13 hours ago, ebrsa said:

Look at JDP's earlier post. First you have to determine whether you are allowed feeding to the grid and then the conditions that apply. Our municipality allows it but credits you R0.685 per Kwh and charges R1.35. No credit balances or rollover to next month is allowed. That makes grid tied a really stupid idea. I have a 2.3Kw panel array, 2 x 4Kwh Axperts in parallel and 450 Ah battery bank. Water is heated by 16 evacuated tube heater. The stove is gas and we use a wood burning heater in winter. Inverters are controlled by AICC program and come on at 1:30 am to 17:30 pm and then switch to grid. Batteries are down to about 80% SOC before the panels generate enough to drive the house and charge the batteries in the morning. So far electricity bill is down by 65%. You have to watch power consumption and not drawn high currents from batteries. I try to stay below 40A. It won't be quite so rosy in winter. On average the house load is around 800W when appliances that draw a lot of power are off. Also it is only my wife and I in the house most of the time.

They live in Tshwane and as far as I know, they can't export (might be wrong).

They are also not very technically knowledgeable and thus my request on info for an out-of-the-box solution, which is why I'm leaning more to recommending a hybrid-system to them.

 

-G-

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10 hours ago, gallderhen said:

They live in Tshwane and as far as I know, they can't export (might be wrong).

They are also not very technically knowledgeable and thus my request on info for an out-of-the-box solution, which is why I'm leaning more to recommending a hybrid-system to them.

 

-G-

An inverter with online monitoring would be a good idea, you or the installer would be able to keep an eye on things to make sure it runs smoothly. 

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On 12/24/2016 at 0:53 PM, HeinTheTerrible said:

I'm still waiting on confirmation about this. I'll keep you guys up to date on this matter.

Mike is the one who told me about the firmware. That is why I went for the Goodwe it self. He works directly with the people at the factory. So I know that to be a fact.

Have you installed a Goodwe ? Do you use them ?

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I don't understand why a grid tie inverter is better than off grid if you don't feed to the grid Hein. Right now (12:00) my panels are generating about 1975W with around 1000W going to the house and about 900W recharging the batteries. It is a clear sunny day so panels are generating close to the maximum that I have seen. How would a grid tie inverter improve the situation.

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Edward I agree with the fact that the true hybrid is better as you are saving your battery bank. You can set the inverter to use eskom to fill the gaps not the batteries. Like in your case when you dont want to put a big load on your bank because your wife has the kettle on. With a true hybrid the bank will only be used when there is no eskom. It will rather pull the difference from eskom that PV can not supply. One of the main reasons I moved away from the Axpert range. You want us to add 'n faction to switch to eskom if the load is to big. A true Hybrid does that already thus putting less strain on the bank when it is cloudy or if the load is too big for PV.

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If it's suggestions for the elderly -- pardon the dark side -- well then part of the equation is that the probability of the owner not being alive for long enough to realise an return on investment is pretty important. You therefore work from the most cost-effective side (pure GTI, no batteries) towards true hybrids and then the semi-hybrid stuff (the switch back and forth models) and only then off-grid, and you stop when the numbers no longer makes sense.

To make it more complicated, these Axperts are so cheap that it might be okay to take one of those over a real hybrid. Would I do such a thing to my own parents though? That is the question :-)

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Thanks Jaco and Plonkster for your explanations, I keep on learning. I hope I will outlast my battery bank but since I treat it with care there is some doubt. I changed the kettle for a 2 Kw one and now my maximum current load is around 40A maximum, ie 20A from each 48V bank. The batteries are at present (14:00) at 85%  and from past experience will be 100% charged later this afternoon. Coulomb's firmware made a big difference. At present I run on solar/battery power from 1:30 until 17:30 with AICC switching the Axperts at those times. In the mornings after breakfast at around 9:00 the batteries are usually at about 78% SOC. Jaco if you at some future date and I am holding thumbs, add a feature where AICC switched to grid and back if the load is above a settable value, the whole process will be automated and I will then have AICC do switching between grid and solar depending on SOC supplied by the BVM700. Even with the present setup my electricity consumption dropped from R1759.08 in June to R621.57 in November which is a drop of 65%. In my particular situation, with 2 people in house most of the time, that is quite significant for the outlay. Other households with different energy needs may not find my installation optimal. There is also zero doubt that Eskom, as a financially challenged company, will have to raise electricity rates substantially in the immediate or at best near future. Then I expect my savings to improve in line with the tariff increases.

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On 26/12/2016 at 0:09 AM, JDP said:

Mike is the one who told me about the firmware. That is why I went for the Goodwe it self. He works directly with the people at the factory. So I know that to be a fact.

Have you installed a Goodwe ? Do you use them ?

I'm not arguing about this. I waiting for confirmation from Renesola SA, I can't see why the exact same unit with a different sticker on cant be updated.

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On 26/12/2016 at 0:02 PM, ebrsa said:

I don't understand why a grid tie inverter is better than off grid if you don't feed to the grid Hein. Right now (12:00) my panels are generating about 1975W with around 1000W going to the house and about 900W recharging the batteries. It is a clear sunny day so panels are generating close to the maximum that I have seen. How would a grid tie inverter improve the situation.

I didn't suggest a grid tie inverter. 

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Hein I find your last comment confusing. The Goodwe is a hybrid but also a grid tie inverter. I had a look at Mike Thorne's system several times as we live in the same village and he installled my system. The problem I encountered early on was that in order to power more than just the base load which in my case is about 750W, one needs panel capacity of 2000W plus. So with a hybrid and small battery bank, a lot of generated power has nowhere to go when the batteries are charged. Battery data sheets claim a long life if, the SOC is kept to 80% maximum. I accept that there are inefficiencies in play when one relies on battery power for part of the day but my present setup is best solution I could come up with AICC on a Raspberry Pi doing the control. Mike has now disconnected his 2 Goodwes from the grid given the municipality's crazy feedback rates and uses excess electricity for Bitcoin mining. His house runs from solar during the day and batteries during the night. He has posted his reasons and setup on the forum. So I cannot fathom how a hybrid inverter is going to improve an installation for gallderhen. Perhaps you would elaborate on your proposal for hybrid inverter.

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Now i use one Goodwe for the kitchen only ( no nagging anymore) one for the rest of the home plus one mining rig doing altcoins and a final inverter running only the extractor fan and the ASIC S9 bitcoin miner...6.6kw of pv with 15kw on inverter and the turbine...think i am sorted out...and btw the bitcoin miner running on solar produced with interest due to bitcoin rising from R10340 on the 1st to R14211 on the 31st, instead of the municipality giving me nada for surplus, i have over R6790 from mining this month.....smoke that Muni..

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