We live in Namibia (so luckily no loadshedding!) and are looking to install a solar system for our house. We have been gifted some solar panels, however, we are unsure which inverter would fit our required use case.

We would like to get the solar up and running without batteries, at least initially. My question is, would an inverter like the 5kW or 8kW Deye Hybrid Inverter be able to handle switching between solar and grid power for power spikes? Let's say a few of our aircon compressors kick in at the same time and that the spike in power draw would exceed, at least for a few fractions of a second, what our panels are producing. Would this spike in power draw be able to be pulled from the grid in that instant? Or can the inverter not switch inputs quickly enough? Can it perhaps aggregate inputs (i.e. draw only the excess power from the grid, thus drawing from two power sources at the same time)? Is there an inverter that can manage any of this?

This problem would be negated with batteries in most setups, since all of the power would just be drawn from the batteries. However we would like to set up the system and start benefitting from it before we gather the funds needed for a proper battery system.

Also, we are unsure what our peak draw is (regarding power spikes) and would appreciate some recommendations on devices that can measure and log power draw, especially the instantaneous spikes, so that we can decide what class of inverter would be best to buy (i.e. 5kW, 8kW, etc.).

We are still very new to this, so apologies if anything is unclear or if this is asked in the wrong place. I'm really hoping someone can help us with this, though!

Yes that is how hybrid inverters work. Deye 5kw or 8kw is a great choice. You would have to set the voltage corresponding to 50% depth of discharge for lead acid and the inverter will handle the rest.

No loadshedding sounds nice. Solar is still a great journey enjoy.

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You would have to set the voltage corresponding to 50% depth of discharge for lead acid and the inverter will handle the rest.

@Buyeye Thank you so much for your reply! I'm sorry, but I don't exactly understand what you mean by this. Would you please clarify? We want to operate without any batteries for the time being, hence the question that I posted.

2 hours ago, xtoswanepoel said:

@Buyeye Thank you so much for your reply! I'm sorry, but I don't exactly understand what you mean by this. Would you please clarify? We want to operate without any batteries for the time being, hence the question that I posted.

Sorry I just reread your post and saw no batteries. I initially assumed you would get cheaper lead acid batteries and set them to 50%. With loadshedding it almost make no sense to spend money on solar and have no electricity during loadshedding.

The inverter would still work without batteries. We will need people who have one to confirm that you just tick no battery.

@xtoswanepoel If loadshedding is not an issue and you want to run without batteries then ideally you would be looking at something like a solis grid-tie inverter with zero feedback to grid if your utility does not allow feedback...

@WannabeSolarSparky How does the Solis grid-tie inverter differ from the Deye 8kW? Would the Deye not be able to switch as fast between solar and grid? Also, we do intend to install batteries at a later stage, so buying an inverter that would work both with and without batteries would be ideal.

the deye/sunsynk inverters work best with batteries, they can work without but will not handle high load switching without batteries.
The scenario you describe is better suited for proper grid-tie inverters as that's what they are designed for.

South Africa is almost unique in that most users get into solar to mitigate loadshedding.
If loadshedding was not an issue most of us would have gone the grid-tie route and add battery systems later if needed and or if budgets allowed.

1 hour ago, xtoswanepoel said:

@WannabeSolarSparky How does the Solis grid-tie inverter differ from the Deye 8kW? Would the Deye not be able to switch as fast between solar and grid? Also, we do intend to install batteries at a later stage, so buying an inverter that would work both with and without batteries would be ideal.

This would be a great call to get the Deye and just run it on the whole DB without battery during the day. If full use of PV the ROI would be around 3 yrs provided you can actually use all the PV generated during the day and you use the maximum PV you can connect to the Deye. This period is based on a current unit cost of about R2.80 in ZA. I understand the cost in NAM is quite higher thus a shorter ROI period is possible.

There is no need for high power equipment to have a battery as the surge currents come directly from the grid what the PV cannot supply.

I take it with switching from solar to grid is when there are clouds? It would instanly just draw from the grid the shortfall PV cannot provide. It is only when using it as a hybrid that there is the delay to connect back to the grid after LS.

Edited January 15, 20242 yr by Scorp007

Interesting that there is no LS in Namibia even though 60% of your power is provided from SA and purchased from Eskom/SAPP😅

Agree with recommendations above, Deye/Sunsynk no batteries and the grid as shortfall. 

12 minutes ago, spotity said:

Interesting that there is no LS in Namibia even though 60% of your power is provided from SA and purchased from Eskom/SAPP😅

Agree with recommendations above, Deye/Sunsynk no batteries and the grid as shortfall. 

Contracts with penalties if supply is not met??? The same reason for other countries in Southern Africa??? 

28 minutes ago, Scorp007 said:

Contracts with penalties if supply is not met??? The same reason for other countries in Southern Africa??? 

Absolutely, sweet deals all round 

I ran my sunsynk 8kw with no batteries for a few weeks. Just panels and grid. It worked fine. But it's always best to have a battery on a hybrid even if it's a small 5kWh

Else go grid tied. 

Edited January 18, 20242 yr by Chris_S

Am seeing potential for you to reduce your reliance on the grid, in the long-term here, just my view. So a Deye/Sunsynk would work with your panels and later you get a battery which means you then split your DB with some circuits being totally off-grid and as you add batteries you add more stuff to go offgrid... that's my 2-cents. With my recommended grid-tied inverters it means priority during the day when you have the sun, you use solar (Pv) and when Pv is not sufficient the inverter then blends with the grid. Also you then, with a CT coil, you do ZERO export to grid.

2 hours ago, Chris_S said:

I ran my sunsynk 8kw with no batteries for a few weeks. Just panels and grid. It worked fine. But it's always best to have a battery on a hybrid even if it's a small 5kWh

Else go grid tied. 

For 99% it works fine and agree on the battery but we need to look at the OP requirements as he gets no LS in NAM.

I would not use a small battery and stay grid tied if I was in his situation. 

@WannabeSolarSparky @Scorp007 @spotity @Chris_S @Moffat Thank you all for your replies! I appreciate the info. We definitely want to get batteries as soon as possible, we just do not have the funding yet. So we'd like an inverter that can run with just solar and grid and that can later be connected to batteries, hence the post.

However, what I'm really concerned about is this: say we're generating 2.5kW from our panels, and it's powering the whole house. All is well. Our draw is ~2kW for argument's sake. Then I turn on an aircon or something that uses ~400W (just an example, pretty sure they draw more). Now when the compressor for the aircon kicks in its draw will likely spike to more than 1000W, meaning my draw will, for a few milliseconds or so, be more than 2.5kW. Will the Deye be able to draw the extra watts (that exceed 2.5kW) from the grid for those few milliseconds? This is what's really bothering me, because if it can't it means that the aircon would likely switch off due to insufficient power being provided to it.

Also, if my panels produce 2.5kW but the house draws 3.7kW, will the Deye inverter be able to split the draw between the solar and the grid (2.5kW from panels and 1.2kW from the grid)? Or will it then draw all 3.7kW from the grid?

Sorry if these are basic questions, but these are the types of things that I don't fully understand about solar power in general yet. Thank you!

57 minutes ago, xtoswanepoel said:

@WannabeSolarSparky @Scorp007 @spotity @Chris_S @Moffat Thank you all for your replies! I appreciate the info. We definitely want to get batteries as soon as possible, we just do not have the funding yet. So we'd like an inverter that can run with just solar and grid and that can later be connected to batteries, hence the post.

However, what I'm really concerned about is this: say we're generating 2.5kW from our panels, and it's powering the whole house. All is well. Our draw is ~2kW for argument's sake. Then I turn on an aircon or something that uses ~400W (just an example, pretty sure they draw more). Now when the compressor for the aircon kicks in its draw will likely spike to more than 1000W, meaning my draw will, for a few milliseconds or so, be more than 2.5kW. Will the Deye be able to draw the extra watts (that exceed 2.5kW) from the grid for those few milliseconds? This is what's really bothering me, because if it can't it means that the aircon would likely switch off due to insufficient power being provided to it.

Also, if my panels produce 2.5kW but the house draws 3.7kW, will the Deye inverter be able to split the draw between the solar and the grid (2.5kW from panels and 1.2kW from the grid)? Or will it then draw all 3.7kW from the grid?

Sorry if these are basic questions, but these are the types of things that I don't fully understand about solar power in general yet. Thank you!

As per my post earlier the power comes from the grid in the 1st place. The grid tied just adds from panels what the panels can produce to lower the grid power. 

I am using 2x1.5kW grid tieds now and for over 4yrs I only used 1x1.5kW. See it as 2 sources where the inverter is just intelligent to ensure all the power it can generate is used 1st and lowers the grid power by this amount. Even if you switch on a stove, geyser, oven at the same instance. Operating this way you can never overload the inverter unless you have put on far too many panels and then the inverter will just limit it's contribution to it's rating. This is then 8kW if using a Sunsynk/Deye. 

This is the most common way how inverters are use overseas where there is a stable grid. The lowest cost method of reducing grid consumption. It also means no split DB and every load on the DB can benefit from this saving from PV. 

Don't worry about basic questions. I have helped a guy using a very large installer that tried to convince him that no inverter can work without a battery-hahaha. The installer learnt a lot when he installed his grid tied inverter. 

Edited January 18, 20242 yr by Scorp007

41 minutes ago, Scorp007 said:

As per my post earlier the power comes from the grid in the 1st place. The grid tied just adds from panels what the panels can produce to lower the grid power. 

I am using 2x1.5kW grid tieds now and for over 4yrs I only used 1x1.5kW. See it as 2 sources where the inverter is just intelligent to ensure all the power it can generate is used 1st and lowers the grid power by this amount. Even if you switch on a stove, geyser, oven at the same instance. Operating this way you can never overload the inverter unless you have put on far too many panels and then the inverter will just limit it's contribution to it's rating. This is then 8kW if using a Sunsynk/Deye. 

This is the most common way how inverters are use overseas where there is a stable grid. The lowest cost method of reducing grid consumption. It also means no split DB and every load on the DB can benefit from this saving from PV. 

Don't worry about basic questions. I have helped a guy using a very large installer that tried to convince him that no inverter can work without a battery-hahaha. The installer learnt a lot when he installed his grid tied inverter. 

Oh I think I understand what you mean now. By grid-tied, do you mean an inverter that feeds back into the grid and by doing so just lowers the amount you pay per month by effectively building up a credit on your account? This means that all your power comes from the grid and not from solar, but it reduces the cost as if you're getting the power from solar directly.

If this is what you mean, that sadly won't work for us since the electricity meters that can do that here in Namibia are awfully expensive, and our levies are massively increased with that meter, and you can only receive credit for what you use. It's a bunch of strange rules and regulations, but in the end it ends up being more expensive than having no solar at all if you have a small home.

What I was really hoping for was an inverter that merges two input power streams into one, i.e. solar and grid. And it just uses more of the grid if it needs extra power that the panels can't produce. I hope I'm not misunderstanding what you're saying! @Scorp007

1 hour ago, xtoswanepoel said:

Oh I think I understand what you mean now. By grid-tied, do you mean an inverter that feeds back into the grid and by doing so just lowers the amount you pay per month by effectively building up a credit on your account? This means that all your power comes from the grid and not from solar, but it reduces the cost as if you're getting the power from solar directly.

If this is what you mean, that sadly won't work for us since the electricity meters that can do that here in Namibia are awfully expensive, and our levies are massively increased with that meter, and you can only receive credit for what you use. It's a bunch of strange rules and regulations, but in the end it ends up being more expensive than having no solar at all if you have a small home.

What I was really hoping for was an inverter that merges two input power streams into one, i.e. solar and grid. And it just uses more of the grid if it needs extra power that the panels can't produce. I hope I'm not misunderstanding what you're saying! @Scorp007

There is flexibility in that you could find a grid-tie inverter that does both export and export limitation.

As an example, look at the Solis S6 4.6kW Dual MPPT inverter, costing around R12,000. It is quite capable of sending power to the grid, but that is not what you want. It can also be installed optionally with a CT coil , and in that case it will only produce solar power for your household loads, blended seamlessly with incoming grid power, but with export limitation. That seems to be what you do want. As long as you have loads to run, it will produce power, and if you have fewer active loads during the day, it will scale back the power generation, use it or lose it. This is a fair option if your grid is very stable, and your loads are mainly run during the day.

A grid-tied inverter cannot operate at night or without the grid, though, nor can it use a battery. If you have intentions of adding a battery backup, you'd best be looking at a grid-tied hybrid like the Solis S6 Pro 5kW Hybrid inverter, costing approx R20,000 instead of around R12,000. It can operate exactly as a grid-tie inverter (but for more money), or alternatively also as an off-grid battery backup system (may as well use it if you've paid for the capability).

Obviously Deye is a competitor brand that you could consider, or maybe you want higher capacity, but I'm just using the example of Solis to illustrate.

Edited January 18, 20242 yr by GreenFields

11 minutes ago, GreenFields said:

There is flexibility in that you could find a grid-tie inverter that does both export and export limitation.

As an example, look at the Solis S6 4.6kW Dual MPPT inverter, costing around . It is quite capable of blending power to the grid, but that is not what you want. It can also be installed optionally with a CT coil , and in that case it will only produce solar power for your household loads, blended seamlessly with incoming grid power, but with export limitation. That seems to be what you do want. As long as you have loads to run, it will produce power, and if you have fewer active loads during the day, it will scale back the power generation, use it or lose it. This is a fair option if your grid is very stable, and your loads are mainly run during the day.

A grid-tied inverter cannot operate at night or without the grid, though, nor can it use a battery. If you have intentions of adding a battery backup, you'd best be looking at a grid-tied hybrid like the Solis S6 Pro 5kW Hybrid inverter, costing approx R20,000 instead of around R12,000. It can operate exactly as a grid-tie inverter (but for more money), or alternatively also as an off-grid battery backup system (may as well use it if you've paid for the capability).

Obviously Deye is a competitor brand that you could consider, or maybe you want higher capacity, but I'm just using the example of Solis to illustrate.

Well explained. 

Without choosing the Solis S6 or the Deye/Sunsynk are great hybrid units for this purpose. I would still go for these hybrids even at a higher price but run them as a without battery system only when the grid is on. The major plus is at a later stage you just add the battery as the OP intends doing. With the battery power can be saved after sunset as well but the cost goes up for this added saving. 

I would not choose the Solis grid tied only (mini 4G) unit although that is what I am using. This prevents you from using a battery. 

In order to prevent confusion perhaps one should talk of a string inverter. Reading up on string inverters will give the details needed. 

The major reason for not using the Solis string inverter even with the CT is that it can take up to 2 seconds to throttle output when one suddenly switches off a high load. This is where a prepaid meter could go into tamper mode. The hybrids are just much faster to throttle. 

Edited January 18, 20242 yr by Scorp007

@GreenFields @Scorp007 This is exactly the info I was looking for! Thank you two so much for sharing your expertise. I'm super glad that there's a chance that the setup could work like we want it to before we get the chance to buy batteries. I'll be back if I have any more questions, you guys are legends! Thanks again

As an aside, do you have any recommendations on devices that can measure whole-house power usage? We don't know what our peak draw is so we don't know what "capacity" inverter to go for (i.e. 5kW, 8kW, etc.)

42 minutes ago, xtoswanepoel said:

@GreenFields @Scorp007 This is exactly the info I was looking for! Thank you two so much for sharing your expertise. I'm super glad that there's a chance that the setup could work like we want it to before we get the chance to buy batteries. I'll be back if I have any more questions, you guys are legends! Thanks again

As an aside, do you have any recommendations on devices that can measure whole-house power usage? We don't know what our peak draw is so we don't know what "capacity" inverter to go for (i.e. 5kW, 8kW, etc.)

https://www.communica.co.za/products/hkd-kws-ac300-lcd-power-meter

It adds up power used that can be reset. It does not record the peak value. Normally peak power is used with geyser on and cooking in the evening. 

There are different models around and I have been using this version for 5yrs.

You don't need to get an inverter that matches your peak. If you have to use some grid for peaks it is the most economical way. Depending on your current day time use will give a good indication of which size. Your peak PV production is in any case only for a few hrs in the day. 

Edited January 18, 20242 yr by Scorp007

On 2024/01/15 at 3:44 PM, xtoswanepoel said:

We would like to get the solar up and running without batteries, at least initially. My question is, would an inverter like the 5kW or 8kW Deye Hybrid Inverter be able to handle switching between solar and grid power for power spikes? Let's say a few of our aircon compressors kick in at the same time and that the spike in power draw would exceed, at least for a few fractions of a second, what our panels are producing. Would this spike in power draw be able to be pulled from the grid in that instant? Or can the inverter not switch inputs quickly enough? Can it perhaps aggregate inputs (i.e. draw only the excess power from the grid, thus drawing from two power sources at the same time)? Is there an inverter that can manage any of this?

You have received good and intelligent answers from various competent Posters. There is however an aspect to mention: That's the energy economics. From my experience our household uses the most energy late afternoon and at night (no aircon). There will be power produced by the PVs that cannot be used and therefore wasted. The battery benefit is that it can store the solar energy harvested during sunshine and makes it available when needed later the day.

@xtoswanepoel As others have already confirmed, there are inverters which will use PV and if the load temporarily exceeds what the PV can produce, it will draw the difference from the grid (for example, when you start an aircon or decide to boil the kettle).

 

Sunsynk/Deye are capable of this, however if you are willing to spend that amount of money I would suggest considering the Solis S6 inverter instead.

The cheapy Luxpower SNA5000 is also capable of this, when I first did my install I only had panels and no batteries and during the day I was using the panels to subsidise my usage and when there was not enough being produced from the panels it would draw what it needed to from the grid.

This Luxpower is a much cheaper inverter (around half the price of the above mentioned inverters), the one downside is that it does has built in fans so it can be noisy - so if you need to install it inside your house it might not be installed.

If you can install it in a room outside or garage, it is worth considering. Due to limited funds, perhaps going for the Luxpower SNA5000 and pairing it with an Svolt 5.43kWh battery might make more sense as the cost would only be slightly higher than purchasing a single 5KW Sunsynk / Deye / Solis inverter and you have the added benefit of having a single battery to start with, which can be used to help save some costs when there is no sunshine (evenings / early mornings) and if there is a bit of cloud coverage the inverter can draw from the battery instead and when the clouds pass then it can charge the battery from the PV.

 

Just a suggestion and something to consider.

 

Also you do need to first see what size inverter you require, keeping in mind you can always start with a smaller 5KW inverter and add a 2nd inverter in parallel later on.

The Sunsynk / Deye / Solis & Luxpower all allow for multiple inverters to be connected in parallel. The added benefit of having multiple inverters in parallel is that you get additional MPPT's (especially useful if you have a roof with multiple sides and panels would be facing various directions) as well as redundancy - so if one inverter breaks you have the other and are not left without an inverter altogether while the inverter is being repaired / replaced.

Also when starting out, if funds are limited, it allows you to get something in the meantime and later on expand on the solar system.

If your needs call for a larger inverter, options can become limited and using multiple smaller inverters can make more sense to achieve the KW rating required.

3 hours ago, PsyCLown said:

@xtoswanepoel

so if one inverter breaks you have the other and are not left without an inverter altogether while the inverter is being repaired / replaced.

Very valid for us having LS. If you always have grid you can carry on without an inverter and just have no savings while being repaired. 

If you use only 1 Luxpower you are limited to 5kW of load while as we have been suggesting with the other inverters you have no limit on the load as all loads are fed from the grid and the inverter just reduce the grid draw based on PV available at any point in time. 

Using a battery for saving after sunset can be an expensive way to save the night time standing load. This will be load profile specific and so far we don't know what the OP is using per month. 

Cannot judge without this info.