Solar Energy

Why are Off-Grid Solar Quotes so High?

The most common reason a quote is ridiculously high is because the system is designed to run on the worst day of the year. This happens because of a lack of communication with the customer about what they want, what they need, and what conservation efforts they’re willing to undertake.

If you have ever asked for a quote for off-grid solar, most likely the first question you were asked was “what is your calculated power usage?”. The entire quote is then based around this one estimate, and a kit that can always support it. One thing customers are never told when getting a quote for off-grid solar? What they can do to lower the cost. We believe this is a massive disservice to a customer.

We believe that the customer should be presented with all the information so that they can make an informed decision about what is best for them. GridFree is not just a solar company, but an off-grid life-style company. This is why we prefer to consult with you on a solution that works best for you, both for your energy needs and cost concerns. This might mean switching heating, cooking, and water to gas, installing a generator that runs a few days of the year, or developing a few energy conservation habits.

To better convey the idea of how conserving a small amount of energy can save you a lot of money, I collected solar statistics for NZ from NIWA, to calculate how much sunlight is produced throughout the year, based on an average of the last five years.

Sunlight hours represent how much sunlight there is during a given day. The easiest way to think about this, is if you have a 100W solar panel, on a 1 sunlight-hour day it will produce 100Wh of energy. On a 6 sunlight-hour day it will produce 600Wh of energy. (Watts multiplied by sunlight hours equals Watthours.) 

Sunlight HoursDays with this much sun or more
0.25365
1362
2339
3301
4239
5169
6111
754
815

The lowest recorded sunlight in one day was 0.25 sunlight hours, this means there are 365 days of the year that produce at least 0.25 sunlight hours. This same calculation was done for each level of sunlight hours. If we look at 3 sunlight hours, we can see that there are 301 days of the year with at least that much sun. Therefore, if you have a 100W solar panel, you know that you will produce at least 300Wh for 301 days or 82% of the year. 

We can then use this to explain what you can run on each of our kits. To give people an idea of which kit would suit them, we provide information on what can be powered on 3 hours of sunlight. For example, this is what can be run on the Bach Kit:

Bach Kit - Appliances that can be run on 3 sunlight hours

 If this suits your needs, then for 301 days of the year, you won’t need to worry about conserving energy. For 38 days, you will be able to use 2/3 of this, and for 23 days, 1/3. There will also be 2-3 days of very tight energy requirements. 

Sunlight HoursDays with this much sun or more% of Baseline Power Generated
0.253658%
136233%
233967%
3301100%
4239133%
5169167%
6111200%
754233%
815 267%

The other thing of note is that for 180 days (half of the year) you will also have more than double the power you need. 

2/3 energy days might look like this:

Bach Kit on 2 Sunlight hours

1/3 like this:

Bach Kit on 1 Sunlight Hour Days

For these 23 days, it may require you to switch some devices off overnight.

The other thing to remember is that this is not 23 consecutive days, but just the total days during the year that are cloudy and stormy. Some of these days may occur during summer or spring, when there will be ample energy in the batteries to rely on anyway.

This table shows roughly how days with 1 or 2 sunlight hours are distributed through the year.

Sunlight HoursMonthNumber of Days
1March3
1April1
1May3
1June4
1July4
1August 3
1September2
1October2
1November1
2January1
2March7
2May7
2June5
2July5
2August4
2September3
2October1
2November1
2December4

The other consideration is how many consecutive days there are with low sun. Looking at the same NIWA estimate data, there are only 8 times a year where there are more than 2 consecutive days of low sun – with 2 occurrences of 5 consecutive days with low sun, one of 4 days, and the rest 3 days.

Here is what the system would cost if you were building it for the same energy usage, based on different sunlight hours.

If you wanted to never worry about power conservation, you would need to spend at least $20k. If you were installing solar in a Bach you only use during the summer, you could base it on 6 hours of sunlight, and you would only need to spend $3950.

Sunlight HoursDays with this much sun or moreSystem CostRecommended Kit
0.25365$20,000Freedom Kit + extra panels + custom battery bank
1362$11,850Freedom Kit + extra panels
2339$6,899Bach Kit + extra panels
3301$5,999Bach Kit
4239$5,540Tiny House Kit + extra panel + extra batteries
5169$4,400Tiny House Kit + extra panel
6111$3,950Tiny House Kit
754$3,500Weekend Warrior Kit
815$3,500Weekend Warrior Kit

If you are ok with these restrictions you will save over $14k in this scenario. These figures get even more extreme when you are looking at larger off-grid solar systems.

Off-grid solar quotes are so high because they’re designed to work on even the lowest sunlight hour days. But they don’t need to be. A simple change in your habits to conserve energy for just a few days can mean thousands of dollars in savings.

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